The Catch-22 of Negative Feedback aka NFB

[Andre Jute]

Some meterhead clown demands to know:
>What's wrong with feedback?<
and another meterhead clown, on being told by Rudy that:
>an OPA2604 ... needs a *thousand* times more feedback<
demands to know:
>So what?

*****
It ain't rocket science. Explanation taken from:
http://members.lycos.co.uk/fiultra/The%20KISS%20Amp%20INDEX.htm

*****
CATCH-22
*****
The customer complained that his new suit didn't fit. 'The sleeves are
too short,' he said to the tailor.

'Yes sir,' said the tailor, 'but if you hold your arm just so, at an
angle as if you're drinking tea with your auntie, it will show just the
right amount of cuff.'

The customer tried it. The tailor was right! 'But what about the other
sleeve? It is definitely too short.'

'Just lower your shoulder, sir. Yes, yes, a little more. Put your foot
out so you can lower your shoulder a little more still. Bend your knee.
Yes, that's it. See how beautifully your suitcoat now fits?'

The customer had to admit the tailor was right. 'Wow. But now the leg
of the pants is all twisted around.'

'That's easily fixed,' said the tailor. 'Just point your other toe
westward, sir, and look over your shoulder to where I am holding up the
hand mirror. See? Doesn't that fit beautifully?'

'Yes,' the customer said doubtfully, 'but-'

'Now would sir like to wear his brilliant new suit or shall we wrap
it?'

The customer was too intimidated to argue. He walked out into the
street in his new suit, his arm crooked as if he were drinking tea, his
other shoulder well down over a bent knee with his foot out to the
side, his other foot pointing westwards, his head twisted back between
hunched shoulders as if complaining to God about a cruel fate.

Behind him he heard a boy say to his father. 'Oh, Daddy, look at the
poor twisted cripple.'

'Hush,' the father said. 'Be grateful the poor man found such a
brilliant tailor.'

****

The Ultrafidelista view of Negative Feedback
by Andre Jute
Negative feedback is the paradigm of modern electronic design. It is
mother's milk to an electronics engineer. He learns to say '100dB of
NFB,' in his sleep before he finishes his first week at the most humble
polytechnic. At the great institutions the professor of feedback is the
most honoured man in the department. In Massachusetts and Minnesota the
feedback guru is the most honoured man on the entire campus, equal in
stature to the football coach. When a guru of transistor high fidelity
(and some in tubes) says, 'I studied under Ron,' one doesn't have to
ask which Ron, one just knows it is the holy name of the prophet of
feedback from the Midwest.

Before I even finished the design of the KISS 300B it was forcefully
suggested by a wannabe guru that with only 50dB more gain (about seven
times as much as is likely to be in the actual design) I can apply 50dB
of negative feedback to linearize my amplifier.

Negative feedback, shorthanded as NFB, is the instant response of the
audio engineering fraternity to all ills, real, perceived,
non-existent. They don't even ask if there is a problem, they swing the
club of NFB regardless. NFB has become a reflex axiom of mainstream
audio design. An audio engineer with his negative feedback is like a
policeman who runs out into the street with his stick and starts
beating a confession out of the first housewife he sees. The difference
is that the policeman is relieved of duty to await punishment and the
audio engineer gets away with it. In the case of the policeman it is
unacceptable behaviour, in the case of the audio engineer so much the
expected norm that no one except the ultrafidelista notice. I guess
that if one in ten million audio amplifiers does not have negative
feedback added, it will be a lot...

No one asked if my KISS Amp requires linearization. The presumption by
all except those already of the ultrafidelista persuasion was that I
would welcome suggestions about A Good Thing.

In the face of such overwhelming acceptance by qualified engineers, why
do we as ultrafidelista not take the same easy path of negative
feedback? Especially considering that superficially NFB is easy to
understand and apply.

How does negative feedback work?
Negative feedback is simply a negative voltage fed back from the output
to the input amplifying device to offset part of the harmonic
distortion which is present as a positive voltage. It costs nothing
except a loss of gain and a few side effects such as phase shift and
possible instability which are well known in the mathematical
literature and more or less easily guarded against depending on the
level of NFB.

'Wow!' those meeting NFB for the first time will now say, 'Something
for free! I'll grab some of that for my amp.' Hey, I said it, and I am
a professional intellectual, by definition an infinite skeptic. NFB is
a thing of beauty that will draw you in. It is like an electronic
Marxism which admits of no contrary arguments because it has subsumed
them all into The Holy Measurements. To question The Measurements is to
commit heresy. You need to be of strong mind to resist the
blandishments of such a universal panacea and of strong stomach to
withstand the hysterical assaults of the lesser engineers defending
their holy grail. (And when you do get hold of a superior engineer to
explain NFB to you, you need to be high-domed indeed because suddenly
NFB can turn very intricate.)

Unfortunately NFB doesn't come without a price. It levies a cruel
charge on the perceived quality of the sound. Negative feedback is what
gives all those 'blameless' transistor and big PP tube amps their
chillingly unnatural sound.

Then how did NFB come to be such a panacea in amplifier design?
Your guess is as good as mine. Hi-fi design is not prestige work for
engineers, or highly paid. The most talented and best qualified
engineers go into automobiles or military hardware or big construction
projects or computer design. The left-overs design amplifiers in the
time they have to spare from writing up specs for requesting a CE mark
for a new electric kettle. Lemmings storming en masse over a cliff come
to mind; such people don't see the necessity of original thought, or
have the mental equipment for it. The exceptions to this rule are
normally audio enthusiasts in charge of their own small audio
manufactories with niche markets; those who grow larger from this base
follow the mainstream mantra of "mo' NFB give lowa' THD" because the
marketing channels demand it from them if they wish to grow. At this
point they usually cease to offer anything different, only the
exclusivity of a very high price. (I know, because a sub-board I
designed for a supplier to the trade turns up in so many very expensive
amps with so many different big names neatly silkscreened on it... it
strikes me as the sort of detail a real designer, as distinct from a
marketer, would take under his own control.) Those very few makers who
will sell you an ultrafi amp without any NFB operate even tinier shops,
usually one man and a cat, just hanging on.

The mechanism by which NFB wrecks your sound
Negative feedback at first acquaintance sounds good enough to take to
bed and cuddle. It isn't. It isn't even as simple as a superficial
acquaintance may suggest. Follow the steps with me, from the theory as
she is received to what arrives at your brain as music:

1. In theory NFB reduces all harmonic distortion equally, without
discrimination. Strictly in theory it does not reshape harmonic
distortion by reducing the most objectionable third and higher order
odd harmonic distortion to a greater extent than the relatively
harmless 2nd harmonic. Thus NFB at its theoretically most benign is
already useless in terms of psychoacoustics, as will become clear at
point 4. If you disregard psychoacoustics, as many audio engineers do,
NFB is brilliant in reducing total harmonic distortion to a number as
tiny as you want. You just pile on more NFB.

2. In real life, as distinct from simplified theory, NFB adds artifacts
of its own. Remember, it is a loop. The signal starts at the input and
is amplified by devices until it reaches the output. From the output a
part of the signal called the negative feedback is fed back to the
input. Here a loop is completed and the combination, less distorted,
reaches the output again, a part of the combination is fed back,
endlessly. The artifacts we want to consider here are created by the
fed-back residue of harmonic distortions adding to both the fundamental
and the distortions already created by the amplifier, then some portion
of the sum of the original and the feedback distortion is fed back
again and added on, until the ooh-ah bird flies up its own fundament.
It looks marginally less disgusting as a recursive mathematical formula
with lots of nested parenthetical parcels of noise being loaded onto
your music. But it is a monkey on the back of your sound, with a
smaller monkey on the back of the first monkey, a still smaller monkey
on the back of the second monkey, and so on ad infinitum. These
additive artifacts are all higher harmonics and the more dominant ones
are all odd. Suppose, for the sake of simplicity, a superbly designed
ultrafidelista amp with some second harmonic and zero odd harmonics
before NFB. Add NFB and the second harmonic will be lowered but the
recombinant new loop now contains newly added intermodulation effects
between the fundamental and the residual second harmonic, and that is
third harmonic. In the next cycle a small but nasty dose of fifth
harmonic that wasn't there before is added by interaction between the
still residual second harmonic and reduced newly added third harmonic.
In short, the artifacts NFB adds to the distortion mix are all of the
most harmful kind. But, say the proponents of NFB, so what? Every time
the loop cycles the added artifacts are smaller, even if there are more
of them... The whole affair starts to smell of trying to argue with a
Marxist who simply declares any inconvenient truth 'an anomaly'. (If
this sounds like a mess from which you should run a mile, you have come
to the right conclusion. Start running now. It gets worse.)

3. We thus arrive at a situation where distortion has been lowered by
NFB but where the most disturbing odd harmonic distortions are still
present to some measure, with the added disadvantage that new and
extremely disturbing artifacts of higher harmonic distortions have been
created by the very process of using negative feedback to lower
distortion. Regardless of the absolute level of THD, or the volume
setting, the mix of harmonics has been adversely affected and now
includes a higher proportion of third and higher harmonics than before
NFB. Let me say that again: after NFB, third and higher harmonics will
make up a greater part of the distortion than before.

4. Low volume levels perforce accounts for 99 per cent of audiophile
listening because we all have families or neighbours, and we would like
to keep our ears. Unfortunately for the lowest common denominator of
hi-fi designer, the one who specifies NFB as a conditioned response
much like Pavlov's dogs slavered when the bell rang, human physiology
and psycho-acoustic response is such that odd harmonics are
disproportionately more disturbing at lower than at higher listening
levels. This inescapable effect is independent of definition of
'listening level.' At the 110dB in-room SPL (only 14dB louder than an
automatic riveter!) advocated by the already deaf Transient Overload
Elite known on newsgroups as the Borg, this poisonous concoction of
original distortions and NFB recombinant artifacts will be least
disturbing (and soon not heard at all!). At any lower level perceived
interference of this harmonics cocktail with the music will increase in
inverse proportion to the volume level. At low volume levels the
artifacts generated by NFB will by their nature as higher harmonic
distortions be disproportionately far more disturbing. At these normal
listening levels 0.75 per cent of second harmonic distortion may be
below the threshhold of perception for sophisticated listeners, whereas
tiny amounts of third and higher odd harmonic distortions grate.

And they still use Negative Feedback? Are they stupid?
No, they are not stupid. Most of them march to the drum of a cost
accountant on whom we wouldn't spit if he were alight. NFB is as cheap
in money terms as it is expensive in terms of perceived quality of
music. We shall come to those who claim to be sympathetic to
high-fidelity but insist on devices which do not work without NFB, who
have another devious answer. Here, meanwhile, for you to keep in mind,
is a single-sentence summary of a complicated interdisciplinary
argument:

The case against NFB is that for 99 per cent of listening the NFB cure
is worse than the disease.

But surely we don't have to do anything so stupid?
It follows from the argument above that ultrafidelista should choose an
intrinsically linear topology and device which does not require added
negative feedback to 'linearize' the output. The intrinsically linear
device is the thermionic tube in either its triode form or as a pentode
hogtied to work as a triode, which can be a most pleasing alternative
both economically and sonically. The topology is often single-ended
operation, chosen also for several other reasons described elsewhere in
these articles, including KISS; if the chosen topology is push-pull
operation, which is more difficult but far from impossible to arrange
without NFB, operation should be specified as Class A1. Inside the
argued case above lies too the overwhelming reason to accept the
potential small disadvantage that may accompany the preferred topology
in comparison to the discarded alternatives. The disadvantage is of
course the potential for a residual second harmonic that measures high
by transistor or NFB tube standards. (Note the word potential. With a
conservatively designed DHT amp the potential problem should not
arise.)

The ultrafidelista, who are as keen on silent amps as anyone else,
accept this small potential difficulty because it is the lesser evil
compared to NFB. Unbelievers (largely unwashed, according to reports)
sneer that ultrafidelista like this approach because of the 'added
euphonics', which is bow-wow techie talk for the warmth a big chunk of
second harmonic lays on a zero negative feedback single-ended
amplifier. But competent design can easily reduce the level of second
harmonic to below the level of perception without the need for NFB and
its deleterious after-effects. In any event, it is your amplifier. You
paid for it. You have a right to tune it as you please. The key thing
is to get rid of NFB and to understand why you did it.

Can we prove any of this scientifically?
We have already. All of this is the technical subtext to my longtime
contention that what the ultrafidelista hear and love is not a directly
heated triode sound as is claimed by many enthusiasts but a Class A1,
ZNFB sound. (Admittedly, as we have seen above, the right sound is
virtually guaranteed with a ZNFB DHT SE amp of conservative provenance
but may have to be developed the hard way with more economical or
higher-power contenders.) In comparative ABX tests conducted over a
number of years, I found that professional musicians, certified golden
ears, choose the triode-linked Class A1 PP ZNFB EL34 whenever it is
present in the test over all other contenders including SE 300B and
'blameless' high-NFB silicon.

Science also proceeds by pure reason. Ultrafidelista have long doubted
whether what engineers insist we measure (the absolute level of
distortion, THD) predicts success in audio gear. This is the full
circle, because I have just proven by logical, individually uncontested
steps that what matters, once a certain modest level of silence is
assured to an amplifier, is not the absolute level of disharmonics but
their composition. The same proof demonstrates that a more beneficial
distribution follows instantly from doing without NFB.

But transistor amps won't work at all without NFB!
That is not our problem. Those who choose inefficient speakers and
consequently are forced to accept monstrous amps made possible only by
gigadeciBels of NFB, will receive our sympathy - and the music they
deserve.

Engineering hangers-on of transistor attempts at high fidelity, where
the measure of success is vanishing THD rather than sonic hedonism,
pretend to be enthusiasts for NFB. To make it work for them, they have
attempted to change the rules so that we won't hear what their
treasured NFB does to our sound. They sneer that low level listening,
which 99 per cent of us prefer and where NFB does most to wreck the
sound, is 'easy listening' and therefore not permissible. According to
them we should all be forced to listen at the high volume level which
suits NFB amps, which they call 'realistic'. This is a contemptible
circular argument, only too characteristic of a fascist mentality in a
part of the audiophile spectrum which wants to prescribe their arid
vision without regard for our enjoyment.

We can recommend a good tailor to them. It hurts every time you wear
his suit. No pain, no gain, fellers!

In summary
Almost everyone listens at low level most of the time. NFB wrecks
everybody's sound at all levels but most wretchedly at normal listening
levels. We started out with a contemptible circular argument and we
have met another along the way. We can now put both in context:

An 'engineer' who designs an amplifier which does not work perfectly
without negative feedback is like a tailor cutting the suit
incompetently and then demanding that you walk like a cripple to make
it fit, so that everyone can admire the brilliance of your tailor.

Negative feedback is a bodge. That is why it is despicable to the
ultrafidelista.

*******
More Zero Negative Feedback amplifiers at Jute on Amps
http://members.lycos.co.uk/fiultra/JUTE%20ON%20AMPS.htm
The KISS Amp project, which explains much more, is here
http://members.lycos.co.uk/fiultra/The%20KISS%20Amp%20INDEX.htm
and its schematics and transfer curves are here
http://members.lycos.co.uk/fiultra/KISS%20190.htm

********
THE VOLTAGES IN THIS AMP WILL KILL YOU.
GET EXPERIENCED SUPERVISION IF IT IS YOUR FIRST TUBE AMP

All text and illustration is Copyright © Andre Jute 2001, 2004, 2006
and may not be reproduced except in the thread KISS xxx on
rec.audio.tubes

[Trevor Wilson]

"Andre Jute" > wrote in message
ups.com...
Some meterhead clown demands to know:
>What's wrong with feedback?<
and another meterhead clown, on being told by Rudy that:
>an OPA2604 ... needs a *thousand* times more feedback<
demands to know:
>So what?

*****
It ain't rocket science. Explanation taken from:
http://members.lycos.co.uk/fiultra/The%20KISS%20Amp%20INDEX.htm

*****
CATCH-22
*****
The customer complained that his new suit didn't fit. 'The sleeves are
too short,' he said to the tailor.

'Yes sir,' said the tailor, 'but if you hold your arm just so, at an
angle as if you're drinking tea with your auntie, it will show just the
right amount of cuff.'

The customer tried it. The tailor was right! 'But what about the other
sleeve? It is definitely too short.'

'Just lower your shoulder, sir. Yes, yes, a little more. Put your foot
out so you can lower your shoulder a little more still. Bend your knee.
Yes, that's it. See how beautifully your suitcoat now fits?'

The customer had to admit the tailor was right. 'Wow. But now the leg
of the pants is all twisted around.'

'That's easily fixed,' said the tailor. 'Just point your other toe
westward, sir, and look over your shoulder to where I am holding up the
hand mirror. See? Doesn't that fit beautifully?'

'Yes,' the customer said doubtfully, 'but-'

'Now would sir like to wear his brilliant new suit or shall we wrap
it?'

The customer was too intimidated to argue. He walked out into the
street in his new suit, his arm crooked as if he were drinking tea, his
other shoulder well down over a bent knee with his foot out to the
side, his other foot pointing westwards, his head twisted back between
hunched shoulders as if complaining to God about a cruel fate.

Behind him he heard a boy say to his father. 'Oh, Daddy, look at the
poor twisted cripple.'

'Hush,' the father said. 'Be grateful the poor man found such a
brilliant tailor.'

****

The Ultrafidelista view of Negative Feedback
by Andre Jute
Negative feedback is the paradigm of modern electronic design. It is
mother's milk to an electronics engineer. He learns to say '100dB of
NFB,' in his sleep before he finishes his first week at the most humble
polytechnic. At the great institutions the professor of feedback is the
most honoured man in the department. In Massachusetts and Minnesota the
feedback guru is the most honoured man on the entire campus, equal in
stature to the football coach. When a guru of transistor high fidelity
(and some in tubes) says, 'I studied under Ron,' one doesn't have to
ask which Ron, one just knows it is the holy name of the prophet of
feedback from the Midwest.

Before I even finished the design of the KISS 300B it was forcefully
suggested by a wannabe guru that with only 50dB more gain (about seven
times as much as is likely to be in the actual design) I can apply 50dB
of negative feedback to linearize my amplifier.

**ALL amplifiers utilise NFB. Every single one. Some do it vai the use of
local feedback loops (like in emitter/cathode degeneration). Some use
internal NFB (such as what occurs within a triode). Some use so-called
'nested feedback' loops, whilst others (the vast majority) use Global
feedback systems. Your KISS 300B uses NFB. Lots of it. Perhaps not as much
as a typical SS amp, but it still uses NFB for linearisation. Without it,
the sound would suck. Big time.


Negative feedback, shorthanded as NFB, is the instant response of the
audio engineering fraternity to all ills, real, perceived,
non-existent. They don't even ask if there is a problem, they swing the
club of NFB regardless. NFB has become a reflex axiom of mainstream
audio design. An audio engineer with his negative feedback is like a
policeman who runs out into the street with his stick and starts
beating a confession out of the first housewife he sees. The difference
is that the policeman is relieved of duty to await punishment and the
audio engineer gets away with it. In the case of the policeman it is
unacceptable behaviour, in the case of the audio engineer so much the
expected norm that no one except the ultrafidelista notice. I guess
that if one in ten million audio amplifiers does not have negative
feedback added, it will be a lot...


**ALL amplifiers utilise NFB for linearisation. Every single one. Not one
amplifier, anywhere, uses Zero NFB. None, nada, zip, zero. So, if you want
to re-state your comment, please do so, but do so ACCURATELY. Define what
types of NFB you are speaking of.


No one asked if my KISS Amp requires linearization. The presumption by
all except those already of the ultrafidelista persuasion was that I
would welcome suggestions about A Good Thing.

In the face of such overwhelming acceptance by qualified engineers, why
do we as ultrafidelista not take the same easy path of negative
feedback? Especially considering that superficially NFB is easy to
understand and apply.

How does negative feedback work?
Negative feedback is simply a negative voltage fed back from the output
to the input amplifying device to offset part of the harmonic
distortion which is present as a positive voltage. It costs nothing
except a loss of gain and a few side effects such as phase shift and
possible instability which are well known in the mathematical
literature and more or less easily guarded against depending on the
level of NFB.

**A gross oversimplification. And you know it. There are many methods of
applying NFB. Some methods have minimal side effects.


'Wow!' those meeting NFB for the first time will now say, 'Something
for free! I'll grab some of that for my amp.' Hey, I said it, and I am
a professional intellectual, by definition an infinite skeptic. NFB is
a thing of beauty that will draw you in. It is like an electronic
Marxism which admits of no contrary arguments because it has subsumed
them all into The Holy Measurements. To question The Measurements is to
commit heresy. You need to be of strong mind to resist the
blandishments of such a universal panacea and of strong stomach to
withstand the hysterical assaults of the lesser engineers defending
their holy grail. (And when you do get hold of a superior engineer to
explain NFB to you, you need to be high-domed indeed because suddenly
NFB can turn very intricate.)

Unfortunately NFB doesn't come without a price. It levies a cruel
charge on the perceived quality of the sound. Negative feedback is what
gives all those 'blameless' transistor and big PP tube amps their
chillingly unnatural sound.

**Er, there is another possibility: NFB allows those amplifiers to provide
clean, undistorted sound. Lack (or more correctly: INSUFFICIENT) NFB merely
alloows an amplifier to possess a distrotion characteristic which is enjoyed
by many listeners.

<ANECDOTE>
Many years ago, I service musical instrument amplifiers (almost always tube
types) on a regular basis. One lead guitarist client was very particular
about his favourite amplifier. It had to produce just the right amount of
distortion. It was an ancient 20 Watt amp, with an inbuilt speaker. The amp
was miked to a large (soild state) PA system. He chose the SS PA system
because it did not distort the sound of his little 20 Watt amp.

</ANECDOTE>


Then how did NFB come to be such a panacea in amplifier design?

**Er, because it works. Your KISS 300B amp uses NFB. YOU know that NFB
works.


Your guess is as good as mine. Hi-fi design is not prestige work for
engineers, or highly paid. The most talented and best qualified
engineers go into automobiles or military hardware or big construction
projects or computer design.

**And, guess what? All modern automobiles use NFB systems of some complexity
in their fuel injection systems. Same deal with military control systems.
Like it or not, NFB is pretty much essential to the operation of all
electronic systems. Including your KISS 300B amplifier.

The left-overs design amplifiers in the
time they have to spare from writing up specs for requesting a CE mark
for a new electric kettle. Lemmings storming en masse over a cliff come
to mind; such people don't see the necessity of original thought, or
have the mental equipment for it. The exceptions to this rule are
normally audio enthusiasts in charge of their own small audio
manufactories with niche markets; those who grow larger from this base
follow the mainstream mantra of "mo' NFB give lowa' THD" because the
marketing channels demand it from them if they wish to grow. At this
point they usually cease to offer anything different, only the
exclusivity of a very high price. (I know, because a sub-board I
designed for a supplier to the trade turns up in so many very expensive
amps with so many different big names neatly silkscreened on it... it
strikes me as the sort of detail a real designer, as distinct from a
marketer, would take under his own control.) Those very few makers who
will sell you an ultrafi amp without any NFB operate even tinier shops,
usually one man and a cat, just hanging on.

**They lie. ALL amplifiers utilise NFB for linearisation. Every single one.
Including your KISS 300B amp.


The mechanism by which NFB wrecks your sound
Negative feedback at first acquaintance sounds good enough to take to
bed and cuddle. It isn't. It isn't even as simple as a superficial
acquaintance may suggest. Follow the steps with me, from the theory as
she is received to what arrives at your brain as music:

1. In theory NFB reduces all harmonic distortion equally, without
discrimination. Strictly in theory it does not reshape harmonic
distortion by reducing the most objectionable third and higher order
odd harmonic distortion to a greater extent than the relatively
harmless 2nd harmonic.

**No distortion is harmless. 2nd harmonic *may* be less objectionable to
SOME listeners. It is not harmless. Moreover, NFB reduces odd order
distortion. And even order distortion.

Thus NFB at its theoretically most benign is
already useless in terms of psychoacoustics, as will become clear at
point 4. If you disregard psychoacoustics, as many audio engineers do,
NFB is brilliant in reducing total harmonic distortion to a number as
tiny as you want. You just pile on more NFB.

2. In real life, as distinct from simplified theory, NFB adds artifacts
of its own. Remember, it is a loop. The signal starts at the input and
is amplified by devices until it reaches the output.

**That would depend on the size of the loop. The NFB loop contained with a
triode is small. As is the loop contained with an emitter degeneration
system. As a consequence, the problems tend to be reduced.

From the output a
part of the signal called the negative feedback is fed back to the
input. Here a loop is completed and the combination, less distorted,
reaches the output again, a part of the combination is fed back,
endlessly. The artifacts we want to consider here are created by the
fed-back residue of harmonic distortions adding to both the fundamental
and the distortions already created by the amplifier, then some portion
of the sum of the original and the feedback distortion is fed back
again and added on, until the ooh-ah bird flies up its own fundament.
It looks marginally less disgusting as a recursive mathematical formula
with lots of nested parenthetical parcels of noise being loaded onto
your music. But it is a monkey on the back of your sound, with a
smaller monkey on the back of the first monkey, a still smaller monkey
on the back of the second monkey, and so on ad infinitum. These
additive artifacts are all higher harmonics and the more dominant ones
are all odd.

**Perhaps. What if these artefacts are above (say) 30kHz and below (say)
0.01% of the total? Are they audible? Can you hear less than 0.01% THD,
regardless of the harmonic structure?

Suppose, for the sake of simplicity, a superbly designed
ultrafidelista amp with some second harmonic and zero odd harmonics
before NFB.

**ALL amplifiers utilise NFB. Every single one. Therre is no such thing as
an amplifier which has no NFB.

Add NFB and the second harmonic will be lowered but the
recombinant new loop now contains newly added intermodulation effects
between the fundamental and the residual second harmonic, and that is
third harmonic. In the next cycle a small but nasty dose of fifth
harmonic that wasn't there before is added by interaction between the
still residual second harmonic and reduced newly added third harmonic.
In short, the artifacts NFB adds to the distortion mix are all of the
most harmful kind. But, say the proponents of NFB, so what? Every time
the loop cycles the added artifacts are smaller, even if there are more
of them... The whole affair starts to smell of trying to argue with a
Marxist who simply declares any inconvenient truth 'an anomaly'. (If
this sounds like a mess from which you should run a mile, you have come
to the right conclusion. Start running now. It gets worse.)


**You're making a whole bunch of bad assumptions. Starting with your most
basic, incorrect assumption: That an amplifier exists which does not use
NFB. It ain't so. ALL amplifiers use NFB. It is tthe TYPE and amount of NFB
which varies between amplifiers.


3. We thus arrive at a situation where distortion has been lowered by
NFB but where the most disturbing odd harmonic distortions are still
present to some measure,

**What if those artefacts are below (say) 0.01%?

with the added disadvantage that new and
extremely disturbing artifacts of higher harmonic distortions have been
created by the very process of using negative feedback to lower
distortion. Regardless of the absolute level of THD, or the volume
setting, the mix of harmonics has been adversely affected and now
includes a higher proportion of third and higher harmonics than before
NFB. Let me say that again: after NFB, third and higher harmonics will
make up a greater part of the distortion than before.

**What if those artefacts are below (say) 0.01%?


4. Low volume levels perforce accounts for 99 per cent of audiophile
listening because we all have families or neighbours, and we would like
to keep our ears.

**Cite you evidence to prove this. Additionally, cite the levels that you
are referring to. Is a "low volume level" equivalent to 0.1 Watt, 1 Watt, 10
Watts, or 100 Watts? Please be specific. What is the room size? Speaker
efficiency? The dynamic range of the recordings used?

Unfortunately for the lowest common denominator of
hi-fi designer, the one who specifies NFB as a conditioned response
much like Pavlov's dogs slavered when the bell rang, human physiology
and psycho-acoustic response is such that odd harmonics are
disproportionately more disturbing at lower than at higher listening
levels. This inescapable effect is independent of definition of
'listening level.' At the 110dB in-room SPL (only 14dB louder than an
automatic riveter!) advocated by the already deaf Transient Overload
Elite known on newsgroups as the Borg, this poisonous concoction of
original distortions and NFB recombinant artifacts will be least
disturbing (and soon not heard at all!). At any lower level perceived
interference of this harmonics cocktail with the music will increase in
inverse proportion to the volume level. At low volume levels the
artifacts generated by NFB will by their nature as higher harmonic
distortions be disproportionately far more disturbing. At these normal
listening levels 0.75 per cent of second harmonic distortion may be
below the threshhold of perception for sophisticated listeners, whereas
tiny amounts of third and higher odd harmonic distortions grate.

**How much odd harmonic distortion? 0.01%? More? Less?


And they still use Negative Feedback?

**All amplifiers use NFB. Every single one.

Are they stupid?

**Your own KISS 300B amplifier uses NFB. Does that make you stupid?

No, they are not stupid. Most of them march to the drum of a cost
accountant on whom we wouldn't spit if he were alight. NFB is as cheap
in money terms as it is expensive in terms of perceived quality of
music. We shall come to those who claim to be sympathetic to
high-fidelity but insist on devices which do not work without NFB, who
have another devious answer. Here, meanwhile, for you to keep in mind,
is a single-sentence summary of a complicated interdisciplinary
argument:

The case against NFB is that for 99 per cent of listening the NFB cure
is worse than the disease.

**ALL amplifiers use NFB. Every single one. If you imagine that one exists
which does not use NFB, then present your evidence.


But surely we don't have to do anything so stupid?
It follows from the argument above that ultrafidelista should choose an
intrinsically linear topology and device which does not require added
negative feedback to 'linearize' the output.

**No such device, nor system exists.

The intrinsically linear
device is the thermionic tube in either its triode form or as a pentode
hogtied to work as a triode, which can be a most pleasing alternative
both economically and sonically.

**Incorrect. On several counts. Triodes utilise an internal NFB system to
linearise their operation. Modern BJTs are more linear than triodes. Yes,
MORE linear. Even quite high power BJTs are very, very linear indeed. More
linear than triodes and MUCH more linear than the accused Pentodes. Get with
the programme and look at the spec sheets (run the curves yourself, if you
wish) of (say) the Toshiba 2SC5200. From less than 0.01A all the way past 3
Amps, it demonstates bugger all variation in gain. Let's see a triode (any
triode) come close to that feat. Modern BJTs are phenomenally linear.
Something which most tube nuts seem blissfully unaware of of, since they
lost interestin transistors back in 1970, when single diffused, low
frequency and highly non-linear devices were the only things available. Move
into the 21st Century and you will se a whole new world of very impressive
devices available to the designer.

The topology is often single-ended
operation, chosen also for several other reasons described elsewhere in
these articles, including KISS;

**Of course. Some listeners enjoy distortion. PP reduces distortion. No
downsides. Just less distortion.

if the chosen topology is push-pull
operation, which is more difficult but far from impossible to arrange
without NFB, operation should be specified as Class A1.

**Why? With suitably matched devices (impossible with tubes, I admit), one
need only organise enough bias current to keep operation in the linear part
of the amplification curve. Any more is wasteful.

Inside the
argued case above lies too the overwhelming reason to accept the
potential small disadvantage that may accompany the preferred topology
in comparison to the discarded alternatives. The disadvantage is of
course the potential for a residual second harmonic that measures high
by transistor or NFB tube standards. (Note the word potential. With a
conservatively designed DHT amp the potential problem should not
arise.)

The ultrafidelista, who are as keen on silent amps as anyone else,
accept this small potential difficulty because it is the lesser evil
compared to NFB.

**ALL amplifiers use NFB. Every single one.

Unbelievers (largely unwashed, according to reports)
sneer that ultrafidelista like this approach because of the 'added
euphonics', which is bow-wow techie talk for the warmth a big chunk of
second harmonic lays on a zero negative feedback single-ended
amplifier.

**There is nothing that a SE design can do that a PP design cannot do
cheaper, better and more efficiently.

But competent design can easily reduce the level of second
harmonic to below the level of perception without the need for NFB and
its deleterious after-effects.

**All amplifier use NFB. Every single one.

In any event, it is your amplifier. You
paid for it. You have a right to tune it as you please. The key thing
is to get rid of NFB and to understand why you did it.

**You can't "get rid" of NFB. Particularly in triode amplifiers. It is built
right into the triode. If you "get rid" of the feedback in a triode, you end
up with a pentode. I prefer to call that an abomination.


Can we prove any of this scientifically?
We have already.

**You first need to prove that an amplifier eixists which can operate
without NFB.

All of this is the technical subtext to my longtime
contention that what the ultrafidelista hear and love is not a directly
heated triode sound as is claimed by many enthusiasts but a Class A1,
ZNFB sound. (Admittedly, as we have seen above, the right sound is
virtually guaranteed with a ZNFB DHT SE amp of conservative provenance
but may have to be developed the hard way with more economical or
higher-power contenders.) In comparative ABX tests conducted over a
number of years, I found that professional musicians, certified golden
ears, choose the triode-linked Class A1 PP ZNFB EL34 whenever it is
present in the test over all other contenders including SE 300B and
'blameless' high-NFB silicon.

**Cite please. Cite SPECIFIC amplifiers used. Cite operating conditions.


Science also proceeds by pure reason. Ultrafidelista have long doubted
whether what engineers insist we measure (the absolute level of
distortion, THD) predicts success in audio gear.

**Duh. It is reasonable assumed by most that levels of THD below (say) 0.1%
are pretty much inaudible. Reductions below this level are pretty much
inconsequential. Conversely, levels ABOVE (say) 0.5% are not
inconsequential. They are audible to many listeners.

This is the full
circle, because I have just proven by logical, individually uncontested
steps that what matters, once a certain modest level of silence is
assured to an amplifier, is not the absolute level of disharmonics but
their composition. The same proof demonstrates that a more beneficial
distribution follows instantly from doing without NFB.

**Nope. Your train of logic is utterly and completely flawed. In several
ways:

* ALL amplifiers use NFB. Every single one.
* Amplifiers of different types, can use widely different types of NFB
application. You have been spectacularly vague about the different types of
NFB available to designers.
* Modern transistors (specifically output transistors) are MUCH more linear
than any tube. Including triodes.

But transistor amps won't work at all without NFB!

**NO AMPLIFIER WORKS WITHOUT NFB. Not one.


That is not our problem. Those who choose inefficient speakers and
consequently are forced to accept monstrous amps made possible only by
gigadeciBels of NFB, will receive our sympathy - and the music they
deserve.

**It is extremely costly and difficult to build high efficiency speakers,
which also possess a wide bandwidth and good dispersion characteristics. If
you know of any, then cite them.


Engineering hangers-on of transistor attempts at high fidelity, where
the measure of success is vanishing THD rather than sonic hedonism,
pretend to be enthusiasts for NFB. To make it work for them, they have
attempted to change the rules so that we won't hear what their
treasured NFB does to our sound. They sneer that low level listening,
which 99 per cent of us prefer and where NFB does most to wreck the
sound, is 'easy listening' and therefore not permissible. According to
them we should all be forced to listen at the high volume level which
suits NFB amps, which they call 'realistic'.

**I know of no listeners who are "forced" to do anything.

This is a contemptible
circular argument, only too characteristic of a fascist mentality in a
part of the audiophile spectrum which wants to prescribe their arid
vision without regard for our enjoyment.

We can recommend a good tailor to them. It hurts every time you wear
his suit. No pain, no gain, fellers!

In summary
Almost everyone listens at low level most of the time.

**Prove it.


NFB wrecks
everybody's sound at all levels but most wretchedly at normal listening
levels.

**Even your own KISS 300B amp, which uses NFB? How curious.

We started out with a contemptible circular argument and we
have met another along the way. We can now put both in context:

An 'engineer' who designs an amplifier which does not work perfectly
without negative feedback is like a tailor cutting the suit
incompetently and then demanding that you walk like a cripple to make
it fit, so that everyone can admire the brilliance of your tailor.

Negative feedback is a bodge. That is why it is despicable to the
ultrafidelista.

**ALL amplifiers use NFB for linearisation. Every single one.



--
Trevor Wilson
www.rageaudio.com.au

[Ruud Broens]

"Trevor Wilson" > wrote in message
...
:
: "Andre Jute" > wrote in message
: ups.com...
: Some meterhead clown demands to know:
: >What's wrong with feedback?<
: and another meterhead clown, on being told by Rudy that:
: >an OPA2604 ... needs a *thousand* times more feedback<
: demands to know:
: >So what?

<snipped lotsastuff youcanreadupwardsinthethread>
: --
: Trevor Wilson
: www.rageaudio.com.au

we've been through this 'linearity contest' before, here.
whereas you define it in terms of current amplification,
i define it in terms of voltage amplification.
as real-world interfacing in audio is with *voltages*,
doesn't seem unreasonable...

excusez for not having included you on the ss
shortlist.
so, why not build flipper's frontend , completed with that
Toshiba 2SC5200 for power
& report back ?

Rudy

[Andre Jute]

Trevor Wilson > wrote:
(a long commentary on my original post, all of it reproduced in full
below)

I never said an amp can work without NFB; that's your desperate spin on
the matter. In fact, I took part in a long thread which determined that
a 300B has about 12-14dB of internal or natural NFB. You, Trevor
Wilson, know that what I actually believe is that most amps work better
without *added* negative feedback. And I told you so again:

> It follows from the argument above that ultrafidelista should choose an
> intrinsically linear topology and device which does not require added
> negative feedback to 'linearize' the output.

See the "added"? It makes clear to even the rawest newbie what I
intend. No one who has been in high level tube amps for more than a
semester needs it spelled out. Everyone knows the convention is that an
amp without added NFB is described as having Zero Negative Feedback.
You, Trevor Wilson, cannot fail to know it, therefore you are picking
desperate nits -- and giving away your desperation by hysterically
screeching your misleading lie "no such thing as a ZNFB amp" over and
over again, probably more than twenty times (those who care can count
below).

Your problem is that you know I'm right but that you have thirty years
invested in commercially telling people tubes are obsolete.

Andre Jute

Here is Trevor Wilson's full commentary:

> "Andre Jute" > wrote in message
> ups.com...
> Some meterhead clown demands to know:
> >What's wrong with feedback?<
> and another meterhead clown, on being told by Rudy that:
> >an OPA2604 ... needs a *thousand* times more feedback<
> demands to know:
> >So what?
>
> *****
> It ain't rocket science. Explanation taken from:
> http://members.lycos.co.uk/fiultra/The%20KISS%20Amp%20INDEX.htm
>
> *****
> CATCH-22
> *****
> The customer complained that his new suit didn't fit. 'The sleeves are
> too short,' he said to the tailor.
>
> 'Yes sir,' said the tailor, 'but if you hold your arm just so, at an
> angle as if you're drinking tea with your auntie, it will show just the
> right amount of cuff.'
>
> The customer tried it. The tailor was right! 'But what about the other
> sleeve? It is definitely too short.'
>
> 'Just lower your shoulder, sir. Yes, yes, a little more. Put your foot
> out so you can lower your shoulder a little more still. Bend your knee.
> Yes, that's it. See how beautifully your suitcoat now fits?'
>
> The customer had to admit the tailor was right. 'Wow. But now the leg
> of the pants is all twisted around.'
>
> 'That's easily fixed,' said the tailor. 'Just point your other toe
> westward, sir, and look over your shoulder to where I am holding up the
> hand mirror. See? Doesn't that fit beautifully?'
>
> 'Yes,' the customer said doubtfully, 'but-'
>
> 'Now would sir like to wear his brilliant new suit or shall we wrap
> it?'
>
> The customer was too intimidated to argue. He walked out into the
> street in his new suit, his arm crooked as if he were drinking tea, his
> other shoulder well down over a bent knee with his foot out to the
> side, his other foot pointing westwards, his head twisted back between
> hunched shoulders as if complaining to God about a cruel fate.
>
> Behind him he heard a boy say to his father. 'Oh, Daddy, look at the
> poor twisted cripple.'
>
> 'Hush,' the father said. 'Be grateful the poor man found such a
> brilliant tailor.'
>
> ****
>
> The Ultrafidelista view of Negative Feedback
> by Andre Jute
> Negative feedback is the paradigm of modern electronic design. It is
> mother's milk to an electronics engineer. He learns to say '100dB of
> NFB,' in his sleep before he finishes his first week at the most humble
> polytechnic. At the great institutions the professor of feedback is the
> most honoured man in the department. In Massachusetts and Minnesota the
> feedback guru is the most honoured man on the entire campus, equal in
> stature to the football coach. When a guru of transistor high fidelity
> (and some in tubes) says, 'I studied under Ron,' one doesn't have to
> ask which Ron, one just knows it is the holy name of the prophet of
> feedback from the Midwest.
>
> Before I even finished the design of the KISS 300B it was forcefully
> suggested by a wannabe guru that with only 50dB more gain (about seven
> times as much as is likely to be in the actual design) I can apply 50dB
> of negative feedback to linearize my amplifier.
>
> **ALL amplifiers utilise NFB. Every single one. Some do it vai the use of
> local feedback loops (like in emitter/cathode degeneration). Some use
> internal NFB (such as what occurs within a triode). Some use so-called
> 'nested feedback' loops, whilst others (the vast majority) use Global
> feedback systems. Your KISS 300B uses NFB. Lots of it. Perhaps not as much
> as a typical SS amp, but it still uses NFB for linearisation. Without it,
> the sound would suck. Big time.
>
>
> Negative feedback, shorthanded as NFB, is the instant response of the
> audio engineering fraternity to all ills, real, perceived,
> non-existent. They don't even ask if there is a problem, they swing the
> club of NFB regardless. NFB has become a reflex axiom of mainstream
> audio design. An audio engineer with his negative feedback is like a
> policeman who runs out into the street with his stick and starts
> beating a confession out of the first housewife he sees. The difference
> is that the policeman is relieved of duty to await punishment and the
> audio engineer gets away with it. In the case of the policeman it is
> unacceptable behaviour, in the case of the audio engineer so much the
> expected norm that no one except the ultrafidelista notice. I guess
> that if one in ten million audio amplifiers does not have negative
> feedback added, it will be a lot...
>
>
> **ALL amplifiers utilise NFB for linearisation. Every single one. Not one
> amplifier, anywhere, uses Zero NFB. None, nada, zip, zero. So, if you want
> to re-state your comment, please do so, but do so ACCURATELY. Define what
> types of NFB you are speaking of.
>
>
> No one asked if my KISS Amp requires linearization. The presumption by
> all except those already of the ultrafidelista persuasion was that I
> would welcome suggestions about A Good Thing.
>
> In the face of such overwhelming acceptance by qualified engineers, why
> do we as ultrafidelista not take the same easy path of negative
> feedback? Especially considering that superficially NFB is easy to
> understand and apply.
>
> How does negative feedback work?
> Negative feedback is simply a negative voltage fed back from the output
> to the input amplifying device to offset part of the harmonic
> distortion which is present as a positive voltage. It costs nothing
> except a loss of gain and a few side effects such as phase shift and
> possible instability which are well known in the mathematical
> literature and more or less easily guarded against depending on the
> level of NFB.
>
> **A gross oversimplification. And you know it. There are many methods of
> applying NFB. Some methods have minimal side effects.
>
>
> 'Wow!' those meeting NFB for the first time will now say, 'Something
> for free! I'll grab some of that for my amp.' Hey, I said it, and I am
> a professional intellectual, by definition an infinite skeptic. NFB is
> a thing of beauty that will draw you in. It is like an electronic
> Marxism which admits of no contrary arguments because it has subsumed
> them all into The Holy Measurements. To question The Measurements is to
> commit heresy. You need to be of strong mind to resist the
> blandishments of such a universal panacea and of strong stomach to
> withstand the hysterical assaults of the lesser engineers defending
> their holy grail. (And when you do get hold of a superior engineer to
> explain NFB to you, you need to be high-domed indeed because suddenly
> NFB can turn very intricate.)
>
> Unfortunately NFB doesn't come without a price. It levies a cruel
> charge on the perceived quality of the sound. Negative feedback is what
> gives all those 'blameless' transistor and big PP tube amps their
> chillingly unnatural sound.
>
> **Er, there is another possibility: NFB allows those amplifiers to provide
> clean, undistorted sound. Lack (or more correctly: INSUFFICIENT) NFB merely
> alloows an amplifier to possess a distrotion characteristic which is enjoyed
> by many listeners.
>
> <ANECDOTE>
> Many years ago, I service musical instrument amplifiers (almost always tube
> types) on a regular basis. One lead guitarist client was very particular
> about his favourite amplifier. It had to produce just the right amount of
> distortion. It was an ancient 20 Watt amp, with an inbuilt speaker. The amp
> was miked to a large (soild state) PA system. He chose the SS PA system
> because it did not distort the sound of his little 20 Watt amp.
>
> </ANECDOTE>
>
>
> Then how did NFB come to be such a panacea in amplifier design?
>
> **Er, because it works. Your KISS 300B amp uses NFB. YOU know that NFB
> works.
>
>
> Your guess is as good as mine. Hi-fi design is not prestige work for
> engineers, or highly paid. The most talented and best qualified
> engineers go into automobiles or military hardware or big construction
> projects or computer design.
>
> **And, guess what? All modern automobiles use NFB systems of some complexity
> in their fuel injection systems. Same deal with military control systems.
> Like it or not, NFB is pretty much essential to the operation of all
> electronic systems. Including your KISS 300B amplifier.
>
> The left-overs design amplifiers in the
> time they have to spare from writing up specs for requesting a CE mark
> for a new electric kettle. Lemmings storming en masse over a cliff come
> to mind; such people don't see the necessity of original thought, or
> have the mental equipment for it. The exceptions to this rule are
> normally audio enthusiasts in charge of their own small audio
> manufactories with niche markets; those who grow larger from this base
> follow the mainstream mantra of "mo' NFB give lowa' THD" because the
> marketing channels demand it from them if they wish to grow. At this
> point they usually cease to offer anything different, only the
> exclusivity of a very high price. (I know, because a sub-board I
> designed for a supplier to the trade turns up in so many very expensive
> amps with so many different big names neatly silkscreened on it... it
> strikes me as the sort of detail a real designer, as distinct from a
> marketer, would take under his own control.) Those very few makers who
> will sell you an ultrafi amp without any NFB operate even tinier shops,
> usually one man and a cat, just hanging on.
>
> **They lie. ALL amplifiers utilise NFB for linearisation. Every single one.
> Including your KISS 300B amp.
>
>
> The mechanism by which NFB wrecks your sound
> Negative feedback at first acquaintance sounds good enough to take to
> bed and cuddle. It isn't. It isn't even as simple as a superficial
> acquaintance may suggest. Follow the steps with me, from the theory as
> she is received to what arrives at your brain as music:
>
> 1. In theory NFB reduces all harmonic distortion equally, without
> discrimination. Strictly in theory it does not reshape harmonic
> distortion by reducing the most objectionable third and higher order
> odd harmonic distortion to a greater extent than the relatively
> harmless 2nd harmonic.
>
> **No distortion is harmless. 2nd harmonic *may* be less objectionable to
> SOME listeners. It is not harmless. Moreover, NFB reduces odd order
> distortion. And even order distortion.
>
> Thus NFB at its theoretically most benign is
> already useless in terms of psychoacoustics, as will become clear at
> point 4. If you disregard psychoacoustics, as many audio engineers do,
> NFB is brilliant in reducing total harmonic distortion to a number as
> tiny as you want. You just pile on more NFB.
>
> 2. In real life, as distinct from simplified theory, NFB adds artifacts
> of its own. Remember, it is a loop. The signal starts at the input and
> is amplified by devices until it reaches the output.
>
> **That would depend on the size of the loop. The NFB loop contained with a
> triode is small. As is the loop contained with an emitter degeneration
> system. As a consequence, the problems tend to be reduced.
>
> From the output a
> part of the signal called the negative feedback is fed back to the
> input. Here a loop is completed and the combination, less distorted,
> reaches the output again, a part of the combination is fed back,
> endlessly. The artifacts we want to consider here are created by the
> fed-back residue of harmonic distortions adding to both the fundamental
> and the distortions already created by the amplifier, then some portion
> of the sum of the original and the feedback distortion is fed back
> again and added on, until the ooh-ah bird flies up its own fundament.
> It looks marginally less disgusting as a recursive mathematical formula
> with lots of nested parenthetical parcels of noise being loaded onto
> your music. But it is a monkey on the back of your sound, with a
> smaller monkey on the back of the first monkey, a still smaller monkey
> on the back of the second monkey, and so on ad infinitum. These
> additive artifacts are all higher harmonics and the more dominant ones
> are all odd.
>
> **Perhaps. What if these artefacts are above (say) 30kHz and below (say)
> 0.01% of the total? Are they audible? Can you hear less than 0.01% THD,
> regardless of the harmonic structure?
>
> Suppose, for the sake of simplicity, a superbly designed
> ultrafidelista amp with some second harmonic and zero odd harmonics
> before NFB.
>
> **ALL amplifiers utilise NFB. Every single one. Therre is no such thing as
> an amplifier which has no NFB.
>
> Add NFB and the second harmonic will be lowered but the
> recombinant new loop now contains newly added intermodulation effects
> between the fundamental and the residual second harmonic, and that is
> third harmonic. In the next cycle a small but nasty dose of fifth
> harmonic that wasn't there before is added by interaction between the
> still residual second harmonic and reduced newly added third harmonic.
> In short, the artifacts NFB adds to the distortion mix are all of the
> most harmful kind. But, say the proponents of NFB, so what? Every time
> the loop cycles the added artifacts are smaller, even if there are more
> of them... The whole affair starts to smell of trying to argue with a
> Marxist who simply declares any inconvenient truth 'an anomaly'. (If
> this sounds like a mess from which you should run a mile, you have come
> to the right conclusion. Start running now. It gets worse.)
>
>
> **You're making a whole bunch of bad assumptions. Starting with your most
> basic, incorrect assumption: That an amplifier exists which does not use
> NFB. It ain't so. ALL amplifiers use NFB. It is tthe TYPE and amount of NFB
> which varies between amplifiers.
>
>
> 3. We thus arrive at a situation where distortion has been lowered by
> NFB but where the most disturbing odd harmonic distortions are still
> present to some measure,
>
> **What if those artefacts are below (say) 0.01%?
>
> with the added disadvantage that new and
> extremely disturbing artifacts of higher harmonic distortions have been
> created by the very process of using negative feedback to lower
> distortion. Regardless of the absolute level of THD, or the volume
> setting, the mix of harmonics has been adversely affected and now
> includes a higher proportion of third and higher harmonics than before
> NFB. Let me say that again: after NFB, third and higher harmonics will
> make up a greater part of the distortion than before.
>
> **What if those artefacts are below (say) 0.01%?
>
>
> 4. Low volume levels perforce accounts for 99 per cent of audiophile
> listening because we all have families or neighbours, and we would like
> to keep our ears.
>
> **Cite you evidence to prove this. Additionally, cite the levels that you
> are referring to. Is a "low volume level" equivalent to 0.1 Watt, 1 Watt, 10
> Watts, or 100 Watts? Please be specific. What is the room size? Speaker
> efficiency? The dynamic range of the recordings used?
>
> Unfortunately for the lowest common denominator of
> hi-fi designer, the one who specifies NFB as a conditioned response
> much like Pavlov's dogs slavered when the bell rang, human physiology
> and psycho-acoustic response is such that odd harmonics are
> disproportionately more disturbing at lower than at higher listening
> levels. This inescapable effect is independent of definition of
> 'listening level.' At the 110dB in-room SPL (only 14dB louder than an
> automatic riveter!) advocated by the already deaf Transient Overload
> Elite known on newsgroups as the Borg, this poisonous concoction of
> original distortions and NFB recombinant artifacts will be least
> disturbing (and soon not heard at all!). At any lower level perceived
> interference of this harmonics cocktail with the music will increase in
> inverse proportion to the volume level. At low volume levels the
> artifacts generated by NFB will by their nature as higher harmonic
> distortions be disproportionately far more disturbing. At these normal
> listening levels 0.75 per cent of second harmonic distortion may be
> below the threshhold of perception for sophisticated listeners, whereas
> tiny amounts of third and higher odd harmonic distortions grate.
>
> **How much odd harmonic distortion? 0.01%? More? Less?
>
>
> And they still use Negative Feedback?
>
> **All amplifiers use NFB. Every single one.
>
> Are they stupid?
>
> **Your own KISS 300B amplifier uses NFB. Does that make you stupid?
>
> No, they are not stupid. Most of them march to the drum of a cost
> accountant on whom we wouldn't spit if he were alight. NFB is as cheap
> in money terms as it is expensive in terms of perceived quality of
> music. We shall come to those who claim to be sympathetic to
> high-fidelity but insist on devices which do not work without NFB, who
> have another devious answer. Here, meanwhile, for you to keep in mind,
> is a single-sentence summary of a complicated interdisciplinary
> argument:
>
> The case against NFB is that for 99 per cent of listening the NFB cure
> is worse than the disease.
>
> **ALL amplifiers use NFB. Every single one. If you imagine that one exists
> which does not use NFB, then present your evidence.
>
>
> But surely we don't have to do anything so stupid?
> It follows from the argument above that ultrafidelista should choose an
> intrinsically linear topology and device which does not require added
> negative feedback to 'linearize' the output.
>
> **No such device, nor system exists.
>
> The intrinsically linear
> device is the thermionic tube in either its triode form or as a pentode
> hogtied to work as a triode, which can be a most pleasing alternative
> both economically and sonically.
>
> **Incorrect. On several counts. Triodes utilise an internal NFB system to
> linearise their operation. Modern BJTs are more linear than triodes. Yes,
> MORE linear. Even quite high power BJTs are very, very linear indeed. More
> linear than triodes and MUCH more linear than the accused Pentodes. Get with
> the programme and look at the spec sheets (run the curves yourself, if you
> wish) of (say) the Toshiba 2SC5200. From less than 0.01A all the way past 3
> Amps, it demonstates bugger all variation in gain. Let's see a triode (any
> triode) come close to that feat. Modern BJTs are phenomenally linear.
> Something which most tube nuts seem blissfully unaware of of, since they
> lost interestin transistors back in 1970, when single diffused, low
> frequency and highly non-linear devices were the only things available. Move
> into the 21st Century and you will se a whole new world of very impressive
> devices available to the designer.
>
> The topology is often single-ended
> operation, chosen also for several other reasons described elsewhere in
> these articles, including KISS;
>
> **Of course. Some listeners enjoy distortion. PP reduces distortion. No
> downsides. Just less distortion.
>
> if the chosen topology is push-pull
> operation, which is more difficult but far from impossible to arrange
> without NFB, operation should be specified as Class A1.
>
> **Why? With suitably matched devices (impossible with tubes, I admit), one
> need only organise enough bias current to keep operation in the linear part
> of the amplification curve. Any more is wasteful.
>
> Inside the
> argued case above lies too the overwhelming reason to accept the
> potential small disadvantage that may accompany the preferred topology
> in comparison to the discarded alternatives. The disadvantage is of
> course the potential for a residual second harmonic that measures high
> by transistor or NFB tube standards. (Note the word potential. With a
> conservatively designed DHT amp the potential problem should not
> arise.)
>
> The ultrafidelista, who are as keen on silent amps as anyone else,
> accept this small potential difficulty because it is the lesser evil
> compared to NFB.
>
> **ALL amplifiers use NFB. Every single one.
>
> Unbelievers (largely unwashed, according to reports)
> sneer that ultrafidelista like this approach because of the 'added
> euphonics', which is bow-wow techie talk for the warmth a big chunk of
> second harmonic lays on a zero negative feedback single-ended
> amplifier.
>
> **There is nothing that a SE design can do that a PP design cannot do
> cheaper, better and more efficiently.
>
> But competent design can easily reduce the level of second
> harmonic to below the level of perception without the need for NFB and
> its deleterious after-effects.
>
> **All amplifier use NFB. Every single one.
>
> In any event, it is your amplifier. You
> paid for it. You have a right to tune it as you please. The key thing
> is to get rid of NFB and to understand why you did it.
>
> **You can't "get rid" of NFB. Particularly in triode amplifiers. It is built
> right into the triode. If you "get rid" of the feedback in a triode, you end
> up with a pentode. I prefer to call that an abomination.
>
>
> Can we prove any of this scientifically?
> We have already.
>
> **You first need to prove that an amplifier eixists which can operate
> without NFB.
>
> All of this is the technical subtext to my longtime
> contention that what the ultrafidelista hear and love is not a directly
> heated triode sound as is claimed by many enthusiasts but a Class A1,
> ZNFB sound. (Admittedly, as we have seen above, the right sound is
> virtually guaranteed with a ZNFB DHT SE amp of conservative provenance
> but may have to be developed the hard way with more economical or
> higher-power contenders.) In comparative ABX tests conducted over a
> number of years, I found that professional musicians, certified golden
> ears, choose the triode-linked Class A1 PP ZNFB EL34 whenever it is
> present in the test over all other contenders including SE 300B and
> 'blameless' high-NFB silicon.
>
> **Cite please. Cite SPECIFIC amplifiers used. Cite operating conditions.
>
>
> Science also proceeds by pure reason. Ultrafidelista have long doubted
> whether what engineers insist we measure (the absolute level of
> distortion, THD) predicts success in audio gear.
>
> **Duh. It is reasonable assumed by most that levels of THD below (say) 0.1%
> are pretty much inaudible. Reductions below this level are pretty much
> inconsequential. Conversely, levels ABOVE (say) 0.5% are not
> inconsequential. They are audible to many listeners.
>
> This is the full
> circle, because I have just proven by logical, individually uncontested
> steps that what matters, once a certain modest level of silence is
> assured to an amplifier, is not the absolute level of disharmonics but
> their composition. The same proof demonstrates that a more beneficial
> distribution follows instantly from doing without NFB.
>
> **Nope. Your train of logic is utterly and completely flawed. In several
> ways:
>
> * ALL amplifiers use NFB. Every single one.
> * Amplifiers of different types, can use widely different types of NFB
> application. You have been spectacularly vague about the different types of
> NFB available to designers.
> * Modern transistors (specifically output transistors) are MUCH more linear
> than any tube. Including triodes.
>
> But transistor amps won't work at all without NFB!
>
> **NO AMPLIFIER WORKS WITHOUT NFB. Not one.
>
>
> That is not our problem. Those who choose inefficient speakers and
> consequently are forced to accept monstrous amps made possible only by
> gigadeciBels of NFB, will receive our sympathy - and the music they
> deserve.
>
> **It is extremely costly and difficult to build high efficiency speakers,
> which also possess a wide bandwidth and good dispersion characteristics. If
> you know of any, then cite them.
>
>
> Engineering hangers-on of transistor attempts at high fidelity, where
> the measure of success is vanishing THD rather than sonic hedonism,
> pretend to be enthusiasts for NFB. To make it work for them, they have
> attempted to change the rules so that we won't hear what their
> treasured NFB does to our sound. They sneer that low level listening,
> which 99 per cent of us prefer and where NFB does most to wreck the
> sound, is 'easy listening' and therefore not permissible. According to
> them we should all be forced to listen at the high volume level which
> suits NFB amps, which they call 'realistic'.
>
> **I know of no listeners who are "forced" to do anything.
>
> This is a contemptible
> circular argument, only too characteristic of a fascist mentality in a
> part of the audiophile spectrum which wants to prescribe their arid
> vision without regard for our enjoyment.
>
> We can recommend a good tailor to them. It hurts every time you wear
> his suit. No pain, no gain, fellers!
>
> In summary
> Almost everyone listens at low level most of the time.
>
> **Prove it.
>
>
> NFB wrecks
> everybody's sound at all levels but most wretchedly at normal listening
> levels.
>
> **Even your own KISS 300B amp, which uses NFB? How curious.
>
> We started out with a contemptible circular argument and we
> have met another along the way. We can now put both in context:
>
> An 'engineer' who designs an amplifier which does not work perfectly
> without negative feedback is like a tailor cutting the suit
> incompetently and then demanding that you walk like a cripple to make
> it fit, so that everyone can admire the brilliance of your tailor.
>
> Negative feedback is a bodge. That is why it is despicable to the
> ultrafidelista.
>
> **ALL amplifiers use NFB for linearisation. Every single one.

[Ruud Broens]

"Trevor Wilson" > wrote in message
...
:
: "Ruud Broens" > wrote in message
: ...
: >
: >
: > we've been through this 'linearity contest' before, here.
: > whereas you define it in terms of current amplification,
: > i define it in terms of voltage amplification.
:
: **In practice, there is no difference. A curent flowing through a resistance
: allows a Voltage to be developed = Voltage gain.
:
: > as real-world interfacing in audio is with *voltages*,
: > doesn't seem unreasonable...
:
: **The difference is academic.
:
: >
: > excusez for not having included you on the ss
: > shortlist.
: > so, why not build flipper's frontend , completed with that
: > Toshiba 2SC5200 for power
: > & report back ?
:
: **Who's "flipper"?
:

he, are you playing inspector ClueSo?
or something ?
get a google clue
:-)
on rat
R.
: --
: Trevor Wilson
: www.rageaudio.com.au
:
:

[Trevor Wilson]

"Andre Jute" > wrote in message
ups.com...
> Trevor Wilson > wrote:
> (a long commentary on my original post, all of it reproduced in full
> below)
>
> I never said an amp can work without NFB;

**Yes, you did. Several times, in fact.

that's your desperate spin on
> the matter. In fact, I took part in a long thread which determined that
> a 300B has about 12-14dB of internal or natural NFB.

**Then why do you persist in claiming that such an amp can exist with no
NFB?

You, Trevor
> Wilson, know that what I actually believe is that most amps work better
> without *added* negative feedback.

**I KNOW that you just published a bunch of lies and half truths. THAT is
what I DO know. If you want to publish a correction (which includes the
superior linearity of modern BJTs over triodes) then I will support you in
that endeavour.

And I told you so again:
>
>> It follows from the argument above that ultrafidelista should choose an
>> intrinsically linear topology and device which does not require added
>> negative feedback to 'linearize' the output.
>
> See the "added"? It makes clear to even the rawest newbie what I
> intend.

**No, it does not. I deal daily with newbies (and a goodly number of those
who aren't newbies) about the issues surrounding NFB. Most have no idea that
ALL amplifiers use NFB of some type for linearisation. Many more have no
idea that a triode utilises and internal NFB system. You have merely
perpetuated these myths. If you want to explain stuff, then be precise. If
you mean local NFB, say so. If you mean Global NFB, say so. If you mean
nested NFB, say so. Each feedback system will affect any given amplifier in
different ways. As you well (or bloody well should) know.

No one who has been in high level tube amps for more than a
> semester needs it spelled out.

**Bull****! I see it every day.

Everyone knows the convention is that an
> amp without added NFB is described as having Zero Negative Feedback.

**Piling more bull**** on top, does not make it so. Spell out EXACTLY what
you mean when you speak of feedback and there'll be fewer problems. If you
mean Zero GLOBAL NFB, then say so. As you well know, not all SS amps utilise
Global NFB for linearisation. In fact, they use similar feedback methods to
your triode amps. And, surprise surprise, they often provide many of the
benefits often ascribed to triode amps, without the obvious shortcomings.
But you would not want to actually educate people, would you?

> You, Trevor Wilson, cannot fail to know it, therefore you are picking
> desperate nits

**Nope. I just get tired of people like you perpetuating lies and half
truths.

-- and giving away your desperation by hysterically
> screeching your misleading lie "no such thing as a ZNFB amp" over and
> over again, probably more than twenty times (those who care can count
> below).

**If you can manage some honesty and accuracy, then I would not nbeed to
correct your mistakes (lies?).

>
> Your problem is that you know I'm right but that you have thirty years
> invested in commercially telling people tubes are obsolete.

**You have no idea.


--
Trevor Wilson
www.rageaudio.com.au

"Trevor Wilson" > wrote in message
...
>
> "Ruud Broens" > wrote in message
> ...
>>
>> "Trevor Wilson" > wrote in message
>> ...
>> :
>> : "Ruud Broens" > wrote in message
>> : ...
>> : >
>> : >
>> : > we've been through this 'linearity contest' before, here.
>> : > whereas you define it in terms of current amplification,
>> : > i define it in terms of voltage amplification.
>> :
>> : **In practice, there is no difference. A curent flowing through a
>> resistance
>> : allows a Voltage to be developed = Voltage gain.
>> :
>> : > as real-world interfacing in audio is with *voltages*,
>> : > doesn't seem unreasonable...
>> :
>> : **The difference is academic.
>> :
>> : >
>> : > excusez for not having included you on the ss
>> : > shortlist.
>> : > so, why not build flipper's frontend , completed with that
>> : > Toshiba 2SC5200 for power
>> : > & report back ?
>> :
>> : **Who's "flipper"?
>> :
>>
>> he, are you playing inspector ClueSo?
>> or something ?
>> get a google clue
>> :-)
>> on rat
>
> **I'll ask again: Who's "flipper"?
>
>
> --
> Trevor Wilson
> www.rageaudio.com.au
One of the regular posters on RAT.

[Stewart Pinkerton]

On 23 Mar 2006 17:37:10 -0800, "Andre Jute" > wrote:

>Trevor Wilson > wrote:
>(a long commentary on my original post, all of it reproduced in full
>below)
>
>I never said an amp can work without NFB; that's your desperate spin on
>the matter. In fact, I took part in a long thread which determined that
>a 300B has about 12-14dB of internal or natural NFB.

'Natural' NFB? You truly are a prize specimen, Jute, you'll tell any
lie and make up any fairy tale to support your utterly farcical
'ultrafidelista' mythology.

> You, Trevor
>Wilson, know that what I actually believe is that most amps work better
>without *added* negative feedback.

If you believe that, then you're wrong.

> And I told you so again:
>
>> It follows from the argument above that ultrafidelista should choose an
>> intrinsically linear topology and device which does not require added
>> negative feedback to 'linearize' the output.
>
>See the "added"? It makes clear to even the rawest newbie what I
>intend. No one who has been in high level tube amps for more than a
>semester needs it spelled out. Everyone knows the convention is that an
>amp without added NFB is described as having Zero Negative Feedback.

The convention is wrong, this is simply mythology put about by those
who are stuck with devices which *cannot* use large amounts of
linearising feedback.

The bottom line is in the output signal, and the output of a good
modern SS amp has *vastly* lower distortion than that of any SET amp.

>You, Trevor Wilson, cannot fail to know it, therefore you are picking
>desperate nits -- and giving away your desperation by hysterically
>screeching your misleading lie "no such thing as a ZNFB amp" over and
>over again, probably more than twenty times (those who care can count
>below).
>
>Your problem is that you know I'm right but that you have thirty years
>invested in commercially telling people tubes are obsolete.

Jute, you know very little about amplifiers, and you are certainly not
right about this. Tubes have been obsolete for the best part of fifty
years, except for fashion victims who like big shiny toys that glow in
the dark.

>Andre Jute

<snip reams of Jute's garbage which he pasted from his hilarious
website>


--

Stewart Pinkerton | Music is Art - Audio is Engineering

Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
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[Bret Ludwig]

Stewart Pinkerton wrote:.
<<snip>>

> >Your problem is that you know I'm right but that you have thirty years
> >invested in commercially telling people tubes are obsolete.
>
> Jute, you know very little about amplifiers, and you are certainly not
> right about this. Tubes have been obsolete for the best part of fifty
> years, except for fashion victims who like big shiny toys that glow in
> the dark.
>
> >Andre Jute



Jute's a ****penis, but the fact is people buy audio equipment like
women buy designer dresses and that isn't going to change. If you want
some booty you let her spend her money the way she wants and don't
balk.

Tubes were the most reliable and best sounding way to build an audio
amplifier up until relatively recent times and they still work very
well when correctly designed. Solid state amplifiers that are truly
well built are not much cheaper than tube ones, and if they made more
tube ones the price would come down and quality go up.

[Andre Jute]

I must say, Wilson, I don't understand why you're getting your knickers
in a knot. You're like those bolshies I used to know who claimed that
anyone who wasn't willing to kill for "socialism" was only play-acting.
Are you really claiming that someone who merely uses the NFB he finds
lurking in DHTs can't belong to the club until he repents and uses
excessive amounts of loop NFB? Are you really claiming that the use of
lots and lots of NFB is a prerequisite for good audio design? Are you
really claiming that because a little NFB is a good thing, an unlimited
amount must therefore be better, and an infinite amount best of all?
Seems a bit immoderate to me, old chap.

Your hysterical belief that I am "against" NFB is the product of your
unsophisticated literal-mindedness. There is no reason for NFB to be an
act of faith, like an on-off switch. For the record, quite contrary to
your silly claims about what I said, I believe the little NFB that
occurs naturally in triodes and in certain conservatively sanctioned
traditional topologies are A Good Thing. To avoid giving you another
apoplectic fit, I shan't repeat what I think of the excessive amounts
of NFB required to make transistors work at all.

If you think you can write a more compelling argument than I can about
the evils of excessive NFB, have at it. But every time I see you, like
the other techies you merely kibbitz what better men have written.

Andre Jute


Trevor Wilson wrote:
> "Andre Jute" > wrote in message
> ups.com...
> > Trevor Wilson > wrote:
> > (a long commentary on my original post, all of it reproduced in full
> > below)
> >
> > I never said an amp can work without NFB;
>
> **Yes, you did. Several times, in fact.
>
> that's your desperate spin on
> > the matter. In fact, I took part in a long thread which determined that
> > a 300B has about 12-14dB of internal or natural NFB.
>
> **Then why do you persist in claiming that such an amp can exist with no
> NFB?
>
> You, Trevor
> > Wilson, know that what I actually believe is that most amps work better
> > without *added* negative feedback.
>
> **I KNOW that you just published a bunch of lies and half truths. THAT is
> what I DO know. If you want to publish a correction (which includes the
> superior linearity of modern BJTs over triodes) then I will support you in
> that endeavour.
>
> And I told you so again:
> >
> >> It follows from the argument above that ultrafidelista should choose an
> >> intrinsically linear topology and device which does not require added
> >> negative feedback to 'linearize' the output.
> >
> > See the "added"? It makes clear to even the rawest newbie what I
> > intend.
>
> **No, it does not. I deal daily with newbies (and a goodly number of those
> who aren't newbies) about the issues surrounding NFB. Most have no idea that
> ALL amplifiers use NFB of some type for linearisation. Many more have no
> idea that a triode utilises and internal NFB system. You have merely
> perpetuated these myths. If you want to explain stuff, then be precise. If
> you mean local NFB, say so. If you mean Global NFB, say so. If you mean
> nested NFB, say so. Each feedback system will affect any given amplifier in
> different ways. As you well (or bloody well should) know.
>
> No one who has been in high level tube amps for more than a
> > semester needs it spelled out.
>
> **Bull****! I see it every day.
>
> Everyone knows the convention is that an
> > amp without added NFB is described as having Zero Negative Feedback.
>
> **Piling more bull**** on top, does not make it so. Spell out EXACTLY what
> you mean when you speak of feedback and there'll be fewer problems. If you
> mean Zero GLOBAL NFB, then say so. As you well know, not all SS amps utilise
> Global NFB for linearisation. In fact, they use similar feedback methods to
> your triode amps. And, surprise surprise, they often provide many of the
> benefits often ascribed to triode amps, without the obvious shortcomings.
> But you would not want to actually educate people, would you?
>
> > You, Trevor Wilson, cannot fail to know it, therefore you are picking
> > desperate nits
>
> **Nope. I just get tired of people like you perpetuating lies and half
> truths.
>
> -- and giving away your desperation by hysterically
> > screeching your misleading lie "no such thing as a ZNFB amp" over and
> > over again, probably more than twenty times (those who care can count
> > below).
>
> **If you can manage some honesty and accuracy, then I would not nbeed to
> correct your mistakes (lies?).
>
> >
> > Your problem is that you know I'm right but that you have thirty years
> > invested in commercially telling people tubes are obsolete.
>
> **You have no idea.
>
>
> --
> Trevor Wilson
> www.rageaudio.com.au

[Trevor Wilson]

"Bret Ludwig" > wrote in message
oups.com...
>
> Stewart Pinkerton wrote:.
> <<snip>>
>
>> >Your problem is that you know I'm right but that you have thirty years
>> >invested in commercially telling people tubes are obsolete.
>>
>> Jute, you know very little about amplifiers, and you are certainly not
>> right about this. Tubes have been obsolete for the best part of fifty
>> years, except for fashion victims who like big shiny toys that glow in
>> the dark.
>>
>> >Andre Jute
>
>
>
> Jute's a ****penis, but the fact is people buy audio equipment like
> women buy designer dresses and that isn't going to change. If you want
> some booty you let her spend her money the way she wants and don't
> balk.

**Irrelevant. Jute lies to get his point accross. If he told the truth, no
one would care either way. When confronted by his obvious lies, he tells
more lies to disguise the fact.

>
> Tubes were the most reliable and best sounding way to build an audio
> amplifier up until relatively recent times

**Up 'till around 1968, that is quite true. It's now almost FOUR DECADES on.
Jute is STILL telling people about transistor amps which have not existed
for several decades.

and they still work very
> well when correctly designed. Solid state amplifiers that are truly
> well built are not much cheaper than tube ones, and if they made more
> tube ones the price would come down and quality go up.

**Utter and complete ********. Due to the presence of the (expensive) output
transformers, alone, tube amps are priced well above an approximately
equivalent SS one.


--
Trevor Wilson
www.rageaudio.com.au

[Arny Krueger]

"Andre Jute" > wrote in message
ups.com

> How does negative feedback work?
> Negative feedback is simply a negative voltage fed back
> from the output to the input amplifying device to offset
> part of the harmonic distortion which is present as a
> positive voltage.

Wrong. The voltage that is fed back in audio power amps is almost always
positive with respect to the input and output of the piece of equipment.
Therefore it is wrong to call it a negative voltage.

Wrong. The voltage that is fed back in audio power amps is simply a fraction
of the output signal. It is not fed back to offset the distortion, but
rather is fed back to offset the foreward-going signal voltage.

> It costs nothing except a loss of gain
> and a few side effects such as phase shift and possible
> instability which are well known in the mathematical
> literature and more or less easily guarded against
> depending on the level of NFB.

Wrong. Negative feedback always reduces phase shift. If misapplied it can
cause an amplifier to become less stable, but in fact when properly applied,
negative feedback increases stability.

Negative feedback increases stability in the sense that it stabilizes the
amplifiers most important technical parameters. For example consider the
gain of an amplifier. If there is no negative feedback, then the gain of an
amplifier is very much exposed to natural variations in the parameters of
its active devices whether they be tubes or solid state. For example, the
gain of both tubes and transistors can be very sensitive to temperature.
With negative feedback, the important parameters of the amplifier are set
by a pair of resistors, whose properties can be made to be very stable and
independent of temperature.

You should get the idea by wrong - Jute has no clue about what negative
feedback is, how it works, or what its real benefits are.

[Arny Krueger]

"Ruud Broens" > wrote in message


> we've been through this 'linearity contest' before, here.
> whereas you define it in terms of current amplification,
> i define it in terms of voltage amplification.
> as real-world interfacing in audio is with *voltages*,
> doesn't seem unreasonable...


Negative feedback is generally used to make amplifiers more linear in the
voltage domain. It's a highly sucessful strategy. We sent men to the moon,
partially based on amplifiers that were linearized with negative feedback.

Where's the beef?

[Ruud Broens]

"Arny Krueger" > wrote in message
...
: "Ruud Broens" > wrote in message
:
:
: > we've been through this 'linearity contest' before, here.
: > whereas you define it in terms of current amplification,
: > i define it in terms of voltage amplification.
: > as real-world interfacing in audio is with *voltages*,
: > doesn't seem unreasonable...
:
:
: Negative feedback is generally used to make amplifiers more linear in the
: voltage domain. It's a highly sucessful strategy. We sent men to the moon,
: partially based on amplifiers that were linearized with negative feedback.
:
: Where's the beef?
:
they 'beef' is, your banana needs 1K more straightening' than my banana -
why keep claiming it is "superior" ?

:-)
Rudy

[Bret Ludwig]

> : > we've been through this 'linearity contest' before, here.
> : > whereas you define it in terms of current amplification,
> : > i define it in terms of voltage amplification.
> : > as real-world interfacing in audio is with *voltages*,
> : > doesn't seem unreasonable...
> :
> :
> : Negative feedback is generally used to make amplifiers more linear in the
> : voltage domain. It's a highly sucessful strategy. We sent men to the moon,
> : partially based on amplifiers that were linearized with negative feedback.


Uhhh, power amplifiers work on complex loads in the power domain?

[Stewart Pinkerton]

On Fri, 24 Mar 2006 12:59:37 +0100, "Ruud Broens" >
wrote:

>"Arny Krueger" > wrote in message
...
>: "Ruud Broens" > wrote in message
>:
>:
>: > we've been through this 'linearity contest' before, here.
>: > whereas you define it in terms of current amplification,
>: > i define it in terms of voltage amplification.
>: > as real-world interfacing in audio is with *voltages*,
>: > doesn't seem unreasonable...
>:
>:
>: Negative feedback is generally used to make amplifiers more linear in the
>: voltage domain. It's a highly sucessful strategy. We sent men to the moon,
>: partially based on amplifiers that were linearized with negative feedback.
>:
>: Where's the beef?
>:
>they 'beef' is, your banana needs 1K more straightening' than my banana -
>why keep claiming it is "superior" ?

Because what matters is the output of the *final* circuit - the banana
is perfectly straight in the opamp, but your tube circuit is still
bendy. The opamp is *designed* to use large amounts of linearising
feedback, something that simply isn't an option with the inherently
much lower open-loop gain of tubes.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
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[Stewart Pinkerton]

On 24 Mar 2006 00:46:36 -0800, "Andre Jute" > wrote:

>I must say, Wilson, I don't understand why you're getting your knickers
>in a knot. You're like those bolshies I used to know who claimed that
>anyone who wasn't willing to kill for "socialism" was only play-acting.
>Are you really claiming that someone who merely uses the NFB he finds
>lurking in DHTs can't belong to the club until he repents and uses
>excessive amounts of loop NFB? Are you really claiming that the use of
>lots and lots of NFB is a prerequisite for good audio design? Are you
>really claiming that because a little NFB is a good thing, an unlimited
>amount must therefore be better, and an infinite amount best of all?
>Seems a bit immoderate to me, old chap.
>
>Your hysterical belief that I am "against" NFB is the product of your
>unsophisticated literal-mindedness. There is no reason for NFB to be an
>act of faith, like an on-off switch. For the record, quite contrary to
>your silly claims about what I said, I believe the little NFB that
>occurs naturally in triodes and in certain conservatively sanctioned
>traditional topologies are A Good Thing. To avoid giving you another
>apoplectic fit, I shan't repeat what I think of the excessive amounts
>of NFB required to make transistors work at all.

As ever, you have no idea what you're talking about. A modern power
transistor such as the 2SC2922 is *more* linear than a 300B, *without*
any feedback. With feedback, due to its gain of 100, it can achieve
linearity far beyond the wildest dreams of the 'ultrafidelista'.

That, of course, is why KISASS will kick the ass of KISS any day of
the week.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
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[Ruud Broens]

"Stewart Pinkerton" > wrote in message
...
: On Fri, 24 Mar 2006 12:59:37 +0100, "Ruud Broens" >
: wrote:
:
: >"Arny Krueger" > wrote in message
: ...
: >: "Ruud Broens" > wrote in message
: >:
: >:
: >: > we've been through this 'linearity contest' before, here.
: >: > whereas you define it in terms of current amplification,
: >: > i define it in terms of voltage amplification.
: >: > as real-world interfacing in audio is with *voltages*,
: >: > doesn't seem unreasonable...
: >:
: >:
: >: Negative feedback is generally used to make amplifiers more linear in the
: >: voltage domain. It's a highly sucessful strategy. We sent men to the moon,
: >: partially based on amplifiers that were linearized with negative feedback.
: >:
: >: Where's the beef?
: >:
: >they 'beef' is, your banana needs 1K more straightening' than my banana -
: >why keep claiming it is "superior" ?
:
: Because what matters is the output of the *final* circuit - the banana
: is perfectly straight in the opamp, but your tube circuit is still
: bendy.

yeah, right, as in 0.007 % distortion kinda bendy.
must be what they call 'the scottish bend',
then
R.

The opamp is *designed* to use large amounts of linearising
: feedback, something that simply isn't an option with the inherently
: much lower open-loop gain of tubes.
: --
:
: Stewart Pinkerton | Music is Art - Audio is Engineering
:
: Posted Via Usenet.com Premium Usenet Newsgroup Services
: ----------------------------------------------------------
: ** SPEED ** RETENTION ** COMPLETION ** ANONYMITY **
: ----------------------------------------------------------
: http://www.usenet.com

[Bret Ludwig]

The details of transistor amplifiers have changed immensely and the
devices have improved, but the physics are still the same as when John
F. Kennedy was holding up operations at Idlewild while pounding on the
Monroe Doctrine in SAM 26000. Bipolar transistors are still low
impedance, current controlled, current controlling devices.

[Ruud Broens]

"Stewart Pinkerton" > wrote in message
...
: On Fri, 24 Mar 2006 17:57:12 +0100, "Ruud Broens" >
: wrote:
:
: >: >: Where's the beef?
: >: >:
: >: >they 'beef' is, your banana needs 1K more straightening' than my banana -
: >: >why keep claiming it is "superior" ?
: >:
: >: Because what matters is the output of the *final* circuit - the banana
: >: is perfectly straight in the opamp, but your tube circuit is still
: >: bendy.
: >
: >yeah, right, as in 0.007 % distortion kinda bendy.
: >must be what they call 'the scottish bend',
: >then
:
: Be more specific about the tubed circuit you claim has this level of
: distortion.
:

eehhrrmm,
don't think that earlier suggestion of a scottish detective will
work out,
after all,

thanks for detecting,
not even well above noise level,
lot'sZZ

:-)
Rudy

[Andre Jute]

Trevor Wilson wrote:
>Incorrect and innappropriate application
> of NFB can damage an amplifier's performance.

Now you're getting it, sonny. Next, try not to describe as a liar
anyone who doesn't instantly subscribe to your fanatical faith in Blow
Jobs from Transvestites (BJTs) and soon the rest of us might take you
seriously.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review


Trevor Wilson wrote:
> "Andre Jute" > wrote in message
> oups.com...
> >I must say, Wilson, I don't understand why you're getting your knickers
> > in a knot.
>
> **They're not and I'm not. I am, however, merely pointing out your more
> obvious lies.
>
> You're like those bolshies I used to know who claimed that
> > anyone who wasn't willing to kill for "socialism" was only play-acting.
> > Are you really claiming that someone who merely uses the NFB he finds
> > lurking in DHTs can't belong to the club until he repents and uses
> > excessive amounts of loop NFB?
>
> **Nope. I merely stated that ALL amplifiers utilise NFB for linearisation.
> You, however, claimed that your amplifiers do not.
>
> Are you really claiming that the use of
> > lots and lots of NFB is a prerequisite for good audio design?
>
> **Nope. I merely stated that ALL amplifiers utilise lots and lots of NFB for
> linearisation. Every single one of them. What differs is HOW that NFB is
> applied (and, of course, how much). Of course, you would not want to
> actually educate your readers, would you? You would prefer to keep them
> confused by your more obvious lies.
>
> Are you
> > really claiming that because a little NFB is a good thing, an unlimited
> > amount must therefore be better, and an infinite amount best of all?
>
> **Where did I claim anything of the sort? Be precise in your cite. What I
> have stated many times, is that CORRECT and APPROPRIATE application of NFB
> will make an amplifier a good one. Incorrect and innappropriate application
> of NFB can damage an amplifier's performance.
>
> > Seems a bit immoderate to me, old chap.
>
> **Wait for the answer, dickhead.
>
> >
> > Your hysterical belief that I am "against" NFB is the product of your
> > unsophisticated literal-mindedness.
>
> **YOU stated it, not me. YOU claimed that certain amplifiers utilised no
> NFB. That is a lie. ALL amplifiers utilise NFB for linearisation. Every
> single one. What differs is the type and amount. You, of course, would not
> want to tell your readers this little fact, would you?
>
>
> There is no reason for NFB to be an
> > act of faith, like an on-off switch. For the record, quite contrary to
> > your silly claims about what I said, I believe the little NFB that
> > occurs naturally in triodes and in certain conservatively sanctioned
> > traditional topologies are A Good Thing.
>
> **LIke I said: ALL amplifiers utilise NFB for linearisation. Every single
> one.
>
>
> To avoid giving you another
> > apoplectic fit, I shan't repeat what I think of the excessive amounts
> > of NFB required to make transistors work at all.
>
> **And again, you lie. It is not necessary to use "excessive amounts" of NFB
> to make a transistor work at all. In fact, modern transistors are more
> linear than tubes and can, therefore, operate with less feedback, if
> required. Because transistors are so cheap and reliable, most manufacturers
> tend to use lots of them and, consequently, lots of NFB to linearise the
> whole shebang.
>
> >
> > If you think you can write a more compelling argument than I can about
> > the evils of excessive NFB, have at it. But every time I see you, like
> > the other techies you merely kibbitz what better men have written.
>
> **I just point out your lies. Nothing more.
>
>
> --
> Trevor Wilson
> www.rageaudio.com.au

[Patrick Turner]

Ruud Broens wrote:

> "Trevor Wilson" > wrote in message
> ...
> :
> : "Ruud Broens" > wrote in message
> : ...
> : >
> : >
> : > we've been through this 'linearity contest' before, here.
> : > whereas you define it in terms of current amplification,
> : > i define it in terms of voltage amplification.
> :
> : **In practice, there is no difference. A curent flowing through a resistance
> : allows a Voltage to be developed = Voltage gain.
> :
> : > as real-world interfacing in audio is with *voltages*,
> : > doesn't seem unreasonable...
> :
> : **The difference is academic.
> :
> : >
> : > excusez for not having included you on the ss
> : > shortlist.
> : > so, why not build flipper's frontend , completed with that
> : > Toshiba 2SC5200 for power
> : > & report back ?
> :
> : **Who's "flipper"?
> :
>
> he, are you playing inspector ClueSo?
> or something ?
> get a google clue
> :-)
> on rat
> R.
> : --
> : Trevor Wilson
> : www.rageaudio.com.au

Hooo is de Fleeper??

Maybeez he is dee BBIIGGG Fishy in de water, and he
SPLASH all over you with heez tail and make you so wet all over.

Patrick Turner.


>
> :
> :

[Andre Jute]

Arny "I spoke in error" Krueger next tries hairsplitting:

> "Andre Jute" > wrote in message
> ups.com
>
> > How does negative feedback work?
> > Negative feedback is simply a negative voltage fed back
> > from the output to the input amplifying device to offset
> > part of the harmonic distortion which is present as a
> > positive voltage.
>
> Wrong. The voltage that is fed back in audio power amps is almost always
> positive with respect to the input and output of the piece of equipment.
> Therefore it is wrong to call it a negative voltage.

If you can't win the argument, redefine the standard terms.

> Wrong. The voltage that is fed back in audio power amps is simply a fraction
> of the output signal. It is not fed back to offset the distortion, but
> rather is fed back to offset the foreward-going signal voltage.

If you can't win the argument, redefine it so narrowly that you can
split hairs about a single tiny piece.

> > It costs nothing except a loss of gain
> > and a few side effects such as phase shift and possible
> > instability which are well known in the mathematical
> > literature and more or less easily guarded against
> > depending on the level of NFB.
>
> Wrong. Negative feedback always reduces phase shift. If misapplied it can
> cause an amplifier to become less stable, but in fact when properly applied,
> negative feedback increases stability.

If you can't win the argument on the specifics, shift ground to the
generality. State that misapplication will always be misapplication, as
if you have just discovered the dull truism.

> Negative feedback increases stability in the sense that it stabilizes the
> amplifiers most important technical parameters. For example consider the
> gain of an amplifier. If there is no negative feedback, then the gain of an
> amplifier is very much exposed to natural variations in the parameters of
> its active devices whether they be tubes or solid state. For example, the
> gain of both tubes and transistors can be very sensitive to temperature.
> With negative feedback, the important parameters of the amplifier are set
> by a pair of resistors, whose properties can be made to be very stable and
> independent of temperature.

If you can't win the argument on its merits, drag in a lot of
extraneous considerations and pretend that each of them is the main
problem.

> You should get the idea by wrong - Jute has no clue about what negative
> feedback is, how it works, or what its real benefits are.

"You should get the idea by wrong" -- duh, Arny? Another Freudian slip?
It tells us poor little Arny, an old man, is still so childish that,
regardless of the facts, he insists on being right and everyone else
being wrong. What a moron.

If you want to be a hairdresser, Krueger, first you should realize that
the purpose of hairdressing is not to promote and increase split ends
but to prevent them. The same in audio with distortion. I thought you
claimed to be an engineer...

Andre Jute
In audio less is hedonism

[Andre Jute]

Patrick Turner wrote:
> Ruud Broens wrote:
>
> > "Trevor Wilson" > wrote in message
> > ...
> > :
> > : "Ruud Broens" > wrote in message
> > : ...
> > : >
> > : >
> > : > we've been through this 'linearity contest' before, here.
> > : > whereas you define it in terms of current amplification,
> > : > i define it in terms of voltage amplification.
> > :
> > : **In practice, there is no difference. A curent flowing through a resistance
> > : allows a Voltage to be developed = Voltage gain.
> > :
> > : > as real-world interfacing in audio is with *voltages*,
> > : > doesn't seem unreasonable...
> > :
> > : **The difference is academic.
> > :
> > : >
> > : > excusez for not having included you on the ss
> > : > shortlist.
> > : > so, why not build flipper's frontend , completed with that
> > : > Toshiba 2SC5200 for power
> > : > & report back ?
> > :
> > : **Who's "flipper"?
> > :
> >
> > he, are you playing inspector ClueSo?
> > or something ?
> > get a google clue
> > :-)
> > on rat
> > R.
> > : --
> > : Trevor Wilson
> > : www.rageaudio.com.au
>
> Hooo is de Fleeper??
>
> Maybeez he is dee BBIIGGG Fishy in de water, and he
> SPLASH all over you with heez tail and make you so wet all over.
>
> Patrick Turner.
>

Poor Trevor is wet all over already. The name of his firm, Rage Audio,
already tells you much about his character. The inchoate mouthfoaming
when he meets the slightest resistance is unnecessary confirmation.

Here's another truth to enrage poor Trevor: It would be easy to show
from the published texts that he and I are in agreement on NFB if only
he will open his mind. I don't suppose he will, though.

Andre Jute

[George M. Middius]

Andre Jute said to DebatingTradeBorg:

> I thought you claimed to be an engineer...

Krooger has amended that claim. He now claims to be "Master of the
Debating Trade". Much more prestigious in his eyes.





--
A day without Krooger is like a day without arsenic.

[John Deans]

"Andre Jute" > wrote in message
ups.com...
Some meterhead clown demands to know:
>What's wrong with feedback?<
and another meterhead clown, on being told by Rudy that:
>an OPA2604 ... needs a *thousand* times more feedback<
demands to know:
>So what?

*****
It ain't rocket science. Explanation taken from:
http://members.lycos.co.uk/fiultra/The%20KISS%20Amp%20INDEX.htm

*****
CATCH-22
*****
The customer complained that his new suit didn't fit. 'The sleeves are
too short,' he said to the tailor.

'Yes sir,' said the tailor, 'but if you hold your arm just so, at an
angle as if you're drinking tea with your auntie, it will show just the
right amount of cuff.'

The customer tried it. The tailor was right! 'But what about the other
sleeve? It is definitely too short.'

'Just lower your shoulder, sir. Yes, yes, a little more. Put your foot
out so you can lower your shoulder a little more still. Bend your knee.
Yes, that's it. See how beautifully your suitcoat now fits?'

The customer had to admit the tailor was right. 'Wow. But now the leg
of the pants is all twisted around.'

'That's easily fixed,' said the tailor. 'Just point your other toe
westward, sir, and look over your shoulder to where I am holding up the
hand mirror. See? Doesn't that fit beautifully?'

'Yes,' the customer said doubtfully, 'but-'

'Now would sir like to wear his brilliant new suit or shall we wrap
it?'

The customer was too intimidated to argue. He walked out into the
street in his new suit, his arm crooked as if he were drinking tea, his
other shoulder well down over a bent knee with his foot out to the
side, his other foot pointing westwards, his head twisted back between
hunched shoulders as if complaining to God about a cruel fate.

Behind him he heard a boy say to his father. 'Oh, Daddy, look at the
poor twisted cripple.'

'Hush,' the father said. 'Be grateful the poor man found such a
brilliant tailor.'

****

The Ultrafidelista view of Negative Feedback
by Andre Jute
Negative feedback is the paradigm of modern electronic design. It is
mother's milk to an electronics engineer. He learns to say '100dB of
NFB,' in his sleep before he finishes his first week at the most humble
polytechnic. At the great institutions the professor of feedback is the
most honoured man in the department. In Massachusetts and Minnesota the
feedback guru is the most honoured man on the entire campus, equal in
stature to the football coach. When a guru of transistor high fidelity
(and some in tubes) says, 'I studied under Ron,' one doesn't have to
ask which Ron, one just knows it is the holy name of the prophet of
feedback from the Midwest.

Before I even finished the design of the KISS 300B it was forcefully
suggested by a wannabe guru that with only 50dB more gain (about seven
times as much as is likely to be in the actual design) I can apply 50dB
of negative feedback to linearize my amplifier.

Negative feedback, shorthanded as NFB, is the instant response of the
audio engineering fraternity to all ills, real, perceived,
non-existent. They don't even ask if there is a problem, they swing the
club of NFB regardless. NFB has become a reflex axiom of mainstream
audio design. An audio engineer with his negative feedback is like a
policeman who runs out into the street with his stick and starts
beating a confession out of the first housewife he sees. The difference
is that the policeman is relieved of duty to await punishment and the
audio engineer gets away with it. In the case of the policeman it is
unacceptable behaviour, in the case of the audio engineer so much the
expected norm that no one except the ultrafidelista notice. I guess
that if one in ten million audio amplifiers does not have negative
feedback added, it will be a lot...

No one asked if my KISS Amp requires linearization. The presumption by
all except those already of the ultrafidelista persuasion was that I
would welcome suggestions about A Good Thing.

In the face of such overwhelming acceptance by qualified engineers, why
do we as ultrafidelista not take the same easy path of negative
feedback? Especially considering that superficially NFB is easy to
understand and apply.

How does negative feedback work?
Negative feedback is simply a negative voltage fed back from the output
to the input amplifying device to offset part of the harmonic
distortion which is present as a positive voltage. It costs nothing
except a loss of gain and a few side effects such as phase shift and
possible instability which are well known in the mathematical
literature and more or less easily guarded against depending on the
level of NFB.

'Wow!' those meeting NFB for the first time will now say, 'Something
for free! I'll grab some of that for my amp.' Hey, I said it, and I am
a professional intellectual, by definition an infinite skeptic. NFB is
a thing of beauty that will draw you in. It is like an electronic
Marxism which admits of no contrary arguments because it has subsumed
them all into The Holy Measurements. To question The Measurements is to
commit heresy. You need to be of strong mind to resist the
blandishments of such a universal panacea and of strong stomach to
withstand the hysterical assaults of the lesser engineers defending
their holy grail. (And when you do get hold of a superior engineer to
explain NFB to you, you need to be high-domed indeed because suddenly
NFB can turn very intricate.)

Unfortunately NFB doesn't come without a price. It levies a cruel
charge on the perceived quality of the sound. Negative feedback is what
gives all those 'blameless' transistor and big PP tube amps their
chillingly unnatural sound.

Then how did NFB come to be such a panacea in amplifier design?
Your guess is as good as mine. Hi-fi design is not prestige work for
engineers, or highly paid. The most talented and best qualified
engineers go into automobiles or military hardware or big construction
projects or computer design. The left-overs design amplifiers in the
time they have to spare from writing up specs for requesting a CE mark
for a new electric kettle. Lemmings storming en masse over a cliff come
to mind; such people don't see the necessity of original thought, or
have the mental equipment for it. The exceptions to this rule are
normally audio enthusiasts in charge of their own small audio
manufactories with niche markets; those who grow larger from this base
follow the mainstream mantra of "mo' NFB give lowa' THD" because the
marketing channels demand it from them if they wish to grow. At this
point they usually cease to offer anything different, only the
exclusivity of a very high price. (I know, because a sub-board I
designed for a supplier to the trade turns up in so many very expensive
amps with so many different big names neatly silkscreened on it... it
strikes me as the sort of detail a real designer, as distinct from a
marketer, would take under his own control.) Those very few makers who
will sell you an ultrafi amp without any NFB operate even tinier shops,
usually one man and a cat, just hanging on.

The mechanism by which NFB wrecks your sound
Negative feedback at first acquaintance sounds good enough to take to
bed and cuddle. It isn't. It isn't even as simple as a superficial
acquaintance may suggest. Follow the steps with me, from the theory as
she is received to what arrives at your brain as music:

1. In theory NFB reduces all harmonic distortion equally, without
discrimination. Strictly in theory it does not reshape harmonic
distortion by reducing the most objectionable third and higher order
odd harmonic distortion to a greater extent than the relatively
harmless 2nd harmonic. Thus NFB at its theoretically most benign is
already useless in terms of psychoacoustics, as will become clear at
point 4. If you disregard psychoacoustics, as many audio engineers do,
NFB is brilliant in reducing total harmonic distortion to a number as
tiny as you want. You just pile on more NFB.

2. In real life, as distinct from simplified theory, NFB adds artifacts
of its own. Remember, it is a loop. The signal starts at the input and
is amplified by devices until it reaches the output. From the output a
part of the signal called the negative feedback is fed back to the
input. Here a loop is completed and the combination, less distorted,
reaches the output again, a part of the combination is fed back,
endlessly. The artifacts we want to consider here are created by the
fed-back residue of harmonic distortions adding to both the fundamental
and the distortions already created by the amplifier, then some portion
of the sum of the original and the feedback distortion is fed back
again and added on, until the ooh-ah bird flies up its own fundament.
It looks marginally less disgusting as a recursive mathematical formula
with lots of nested parenthetical parcels of noise being loaded onto
your music. But it is a monkey on the back of your sound, with a
smaller monkey on the back of the first monkey, a still smaller monkey
on the back of the second monkey, and so on ad infinitum. These
additive artifacts are all higher harmonics and the more dominant ones
are all odd. Suppose, for the sake of simplicity, a superbly designed
ultrafidelista amp with some second harmonic and zero odd harmonics
before NFB. Add NFB and the second harmonic will be lowered but the
recombinant new loop now contains newly added intermodulation effects
between the fundamental and the residual second harmonic, and that is
third harmonic. In the next cycle a small but nasty dose of fifth
harmonic that wasn't there before is added by interaction between the
still residual second harmonic and reduced newly added third harmonic.
In short, the artifacts NFB adds to the distortion mix are all of the
most harmful kind. But, say the proponents of NFB, so what? Every time
the loop cycles the added artifacts are smaller, even if there are more
of them... The whole affair starts to smell of trying to argue with a
Marxist who simply declares any inconvenient truth 'an anomaly'. (If
this sounds like a mess from which you should run a mile, you have come
to the right conclusion. Start running now. It gets worse.)

3. We thus arrive at a situation where distortion has been lowered by
NFB but where the most disturbing odd harmonic distortions are still
present to some measure, with the added disadvantage that new and
extremely disturbing artifacts of higher harmonic distortions have been
created by the very process of using negative feedback to lower
distortion. Regardless of the absolute level of THD, or the volume
setting, the mix of harmonics has been adversely affected and now
includes a higher proportion of third and higher harmonics than before
NFB. Let me say that again: after NFB, third and higher harmonics will
make up a greater part of the distortion than before.

4. Low volume levels perforce accounts for 99 per cent of audiophile
listening because we all have families or neighbours, and we would like
to keep our ears. Unfortunately for the lowest common denominator of
hi-fi designer, the one who specifies NFB as a conditioned response
much like Pavlov's dogs slavered when the bell rang, human physiology
and psycho-acoustic response is such that odd harmonics are
disproportionately more disturbing at lower than at higher listening
levels. This inescapable effect is independent of definition of
'listening level.' At the 110dB in-room SPL (only 14dB louder than an
automatic riveter!) advocated by the already deaf Transient Overload
Elite known on newsgroups as the Borg, this poisonous concoction of
original distortions and NFB recombinant artifacts will be least
disturbing (and soon not heard at all!). At any lower level perceived
interference of this harmonics cocktail with the music will increase in
inverse proportion to the volume level. At low volume levels the
artifacts generated by NFB will by their nature as higher harmonic
distortions be disproportionately far more disturbing. At these normal
listening levels 0.75 per cent of second harmonic distortion may be
below the threshhold of perception for sophisticated listeners, whereas
tiny amounts of third and higher odd harmonic distortions grate.

And they still use Negative Feedback? Are they stupid?
No, they are not stupid. Most of them march to the drum of a cost
accountant on whom we wouldn't spit if he were alight. NFB is as cheap
in money terms as it is expensive in terms of perceived quality of
music. We shall come to those who claim to be sympathetic to
high-fidelity but insist on devices which do not work without NFB, who
have another devious answer. Here, meanwhile, for you to keep in mind,
is a single-sentence summary of a complicated interdisciplinary
argument:

The case against NFB is that for 99 per cent of listening the NFB cure
is worse than the disease.

But surely we don't have to do anything so stupid?
It follows from the argument above that ultrafidelista should choose an
intrinsically linear topology and device which does not require added
negative feedback to 'linearize' the output. The intrinsically linear
device is the thermionic tube in either its triode form or as a pentode
hogtied to work as a triode, which can be a most pleasing alternative
both economically and sonically. The topology is often single-ended
operation, chosen also for several other reasons described elsewhere in
these articles, including KISS; if the chosen topology is push-pull
operation, which is more difficult but far from impossible to arrange
without NFB, operation should be specified as Class A1. Inside the
argued case above lies too the overwhelming reason to accept the
potential small disadvantage that may accompany the preferred topology
in comparison to the discarded alternatives. The disadvantage is of
course the potential for a residual second harmonic that measures high
by transistor or NFB tube standards. (Note the word potential. With a
conservatively designed DHT amp the potential problem should not
arise.)

The ultrafidelista, who are as keen on silent amps as anyone else,
accept this small potential difficulty because it is the lesser evil
compared to NFB. Unbelievers (largely unwashed, according to reports)
sneer that ultrafidelista like this approach because of the 'added
euphonics', which is bow-wow techie talk for the warmth a big chunk of
second harmonic lays on a zero negative feedback single-ended
amplifier. But competent design can easily reduce the level of second
harmonic to below the level of perception without the need for NFB and
its deleterious after-effects. In any event, it is your amplifier. You
paid for it. You have a right to tune it as you please. The key thing
is to get rid of NFB and to understand why you did it.

Can we prove any of this scientifically?
We have already. All of this is the technical subtext to my longtime
contention that what the ultrafidelista hear and love is not a directly
heated triode sound as is claimed by many enthusiasts but a Class A1,
ZNFB sound. (Admittedly, as we have seen above, the right sound is
virtually guaranteed with a ZNFB DHT SE amp of conservative provenance
but may have to be developed the hard way with more economical or
higher-power contenders.) In comparative ABX tests conducted over a
number of years, I found that professional musicians, certified golden
ears, choose the triode-linked Class A1 PP ZNFB EL34 whenever it is
present in the test over all other contenders including SE 300B and
'blameless' high-NFB silicon.

Science also proceeds by pure reason. Ultrafidelista have long doubted
whether what engineers insist we measure (the absolute level of
distortion, THD) predicts success in audio gear. This is the full
circle, because I have just proven by logical, individually uncontested
steps that what matters, once a certain modest level of silence is
assured to an amplifier, is not the absolute level of disharmonics but
their composition. The same proof demonstrates that a more beneficial
distribution follows instantly from doing without NFB.

But transistor amps won't work at all without NFB!
That is not our problem. Those who choose inefficient speakers and
consequently are forced to accept monstrous amps made possible only by
gigadeciBels of NFB, will receive our sympathy - and the music they
deserve.

Engineering hangers-on of transistor attempts at high fidelity, where
the measure of success is vanishing THD rather than sonic hedonism,
pretend to be enthusiasts for NFB. To make it work for them, they have
attempted to change the rules so that we won't hear what their
treasured NFB does to our sound. They sneer that low level listening,
which 99 per cent of us prefer and where NFB does most to wreck the
sound, is 'easy listening' and therefore not permissible. According to
them we should all be forced to listen at the high volume level which
suits NFB amps, which they call 'realistic'. This is a contemptible
circular argument, only too characteristic of a fascist mentality in a
part of the audiophile spectrum which wants to prescribe their arid
vision without regard for our enjoyment.

We can recommend a good tailor to them. It hurts every time you wear
his suit. No pain, no gain, fellers!

In summary
Almost everyone listens at low level most of the time. NFB wrecks
everybody's sound at all levels but most wretchedly at normal listening
levels. We started out with a contemptible circular argument and we
have met another along the way. We can now put both in context:

An 'engineer' who designs an amplifier which does not work perfectly
without negative feedback is like a tailor cutting the suit
incompetently and then demanding that you walk like a cripple to make
it fit, so that everyone can admire the brilliance of your tailor.

Negative feedback is a bodge. That is why it is despicable to the
ultrafidelista.

*******
More Zero Negative Feedback amplifiers at Jute on Amps
http://members.lycos.co.uk/fiultra/JUTE%20ON%20AMPS.htm
The KISS Amp project, which explains much more, is here
http://members.lycos.co.uk/fiultra/The%20KISS%20Amp%20INDEX.htm
and its schematics and transfer curves are here
http://members.lycos.co.uk/fiultra/KISS%20190.htm

********
THE VOLTAGES IN THIS AMP WILL KILL YOU.
GET EXPERIENCED SUPERVISION IF IT IS YOUR FIRST TUBE AMP

All text and illustration is Copyright © Andre Jute 2001, 2004, 2006
and may not be reproduced except in the thread KISS xxx on
rec.audio.tubes

[Patrick Turner]

Andre Jute wrote:

> I must say, Wilson, I don't understand why you're getting your knickers
> in a knot. You're like those bolshies I used to know who claimed that
> anyone who wasn't willing to kill for "socialism" was only play-acting.
> Are you really claiming that someone who merely uses the NFB he finds
> lurking in DHTs can't belong to the club until he repents and uses
> excessive amounts of loop NFB? Are you really claiming that the use of
> lots and lots of NFB is a prerequisite for good audio design? Are you
> really claiming that because a little NFB is a good thing, an unlimited
> amount must therefore be better, and an infinite amount best of all?
> Seems a bit immoderate to me, old chap.

You will find yourself arguing at a man who has a head full of solid concrete.
Trev will never see the whole picture, and has never designed or built any amp in
the last 30 years.
I try not to bother arguing the same old tired BS time after time.
He just likes hanging out in news groups and Bull****ting.
He has NEVER once contributed a single article of constructive advice on tubecraft
at r.a.t.

>
>
> Your hysterical belief that I am "against" NFB is the product of your
> unsophisticated literal-mindedness. There is no reason for NFB to be an
> act of faith, like an on-off switch. For the record, quite contrary to
> your silly claims about what I said, I believe the little NFB that
> occurs naturally in triodes and in certain conservatively sanctioned
> traditional topologies are A Good Thing. To avoid giving you another
> apoplectic fit, I shan't repeat what I think of the excessive amounts
> of NFB required to make transistors work at all.
>
> If you think you can write a more compelling argument than I can about
> the evils of excessive NFB, have at it. But every time I see you, like
> the other techies you merely kibbitz what better men have written.

I am now doing 845 amps, two per channel for 50 watts each.
I expect music to be real fine. Damping factor good, noise low,
bandwidth wide, distortions negligible and maybe I can add 6db of global NFB but
I doubt any difference due to some **added** NFB will be heard.

Trev has never done anything like this and simply doesn't understand.

With 845, just no need for the 106dB of added NFB used in SS amps.
I don't care a bit about what Trev says.

Patrick Turner.




>
>
> Andre Jute
>
> Trevor Wilson wrote:
> > "Andre Jute" > wrote in message
> > ups.com...
> > > Trevor Wilson > wrote:
> > > (a long commentary on my original post, all of it reproduced in full
> > > below)
> > >
> > > I never said an amp can work without NFB;
> >
> > **Yes, you did. Several times, in fact.
> >
> > that's your desperate spin on
> > > the matter. In fact, I took part in a long thread which determined that
> > > a 300B has about 12-14dB of internal or natural NFB.
> >
> > **Then why do you persist in claiming that such an amp can exist with no
> > NFB?
> >
> > You, Trevor
> > > Wilson, know that what I actually believe is that most amps work better
> > > without *added* negative feedback.
> >
> > **I KNOW that you just published a bunch of lies and half truths. THAT is
> > what I DO know. If you want to publish a correction (which includes the
> > superior linearity of modern BJTs over triodes) then I will support you in
> > that endeavour.
> >
> > And I told you so again:
> > >
> > >> It follows from the argument above that ultrafidelista should choose an
> > >> intrinsically linear topology and device which does not require added
> > >> negative feedback to 'linearize' the output.
> > >
> > > See the "added"? It makes clear to even the rawest newbie what I
> > > intend.
> >
> > **No, it does not. I deal daily with newbies (and a goodly number of those
> > who aren't newbies) about the issues surrounding NFB. Most have no idea that
> > ALL amplifiers use NFB of some type for linearisation. Many more have no
> > idea that a triode utilises and internal NFB system. You have merely
> > perpetuated these myths. If you want to explain stuff, then be precise. If
> > you mean local NFB, say so. If you mean Global NFB, say so. If you mean
> > nested NFB, say so. Each feedback system will affect any given amplifier in
> > different ways. As you well (or bloody well should) know.
> >
> > No one who has been in high level tube amps for more than a
> > > semester needs it spelled out.
> >
> > **Bull****! I see it every day.
> >
> > Everyone knows the convention is that an
> > > amp without added NFB is described as having Zero Negative Feedback.
> >
> > **Piling more bull**** on top, does not make it so. Spell out EXACTLY what
> > you mean when you speak of feedback and there'll be fewer problems. If you
> > mean Zero GLOBAL NFB, then say so. As you well know, not all SS amps utilise
> > Global NFB for linearisation. In fact, they use similar feedback methods to
> > your triode amps. And, surprise surprise, they often provide many of the
> > benefits often ascribed to triode amps, without the obvious shortcomings.
> > But you would not want to actually educate people, would you?
> >
> > > You, Trevor Wilson, cannot fail to know it, therefore you are picking
> > > desperate nits
> >
> > **Nope. I just get tired of people like you perpetuating lies and half
> > truths.
> >
> > -- and giving away your desperation by hysterically
> > > screeching your misleading lie "no such thing as a ZNFB amp" over and
> > > over again, probably more than twenty times (those who care can count
> > > below).
> >
> > **If you can manage some honesty and accuracy, then I would not nbeed to
> > correct your mistakes (lies?).
> >
> > >
> > > Your problem is that you know I'm right but that you have thirty years
> > > invested in commercially telling people tubes are obsolete.
> >
> > **You have no idea.
> >
> >
> > --
> > Trevor Wilson
> > www.rageaudio.com.au

[John Deans]

Just another Hi Fi nut who has built an amp thinks it sounds good but is it
accurate or a nice sound
negative feedback is almost necessary in transistor amps used well it works
fine and much has been written on good transistor amp design
I will put my pro transistor amps against most valve amps anyway
Tinted glasses make the world look better but are they accurate

..
"Andre Jute" > wrote in message
ups.com...
Some meterhead clown demands to know:
>What's wrong with feedback?<
and another meterhead clown, on being told by Rudy that:
>an OPA2604 ... needs a *thousand* times more feedback<
demands to know:
>So what?

*****
It ain't rocket science. Explanation taken from:
http://members.lycos.co.uk/fiultra/The%20KISS%20Amp%20INDEX.htm

*****
CATCH-22
*****
The customer complained that his new suit didn't fit. 'The sleeves are
too short,' he said to the tailor.

'Yes sir,' said the tailor, 'but if you hold your arm just so, at an
angle as if you're drinking tea with your auntie, it will show just the
right amount of cuff.'

The customer tried it. The tailor was right! 'But what about the other
sleeve? It is definitely too short.'

'Just lower your shoulder, sir. Yes, yes, a little more. Put your foot
out so you can lower your shoulder a little more still. Bend your knee.
Yes, that's it. See how beautifully your suitcoat now fits?'

The customer had to admit the tailor was right. 'Wow. But now the leg
of the pants is all twisted around.'

'That's easily fixed,' said the tailor. 'Just point your other toe
westward, sir, and look over your shoulder to where I am holding up the
hand mirror. See? Doesn't that fit beautifully?'

'Yes,' the customer said doubtfully, 'but-'

'Now would sir like to wear his brilliant new suit or shall we wrap
it?'

The customer was too intimidated to argue. He walked out into the
street in his new suit, his arm crooked as if he were drinking tea, his
other shoulder well down over a bent knee with his foot out to the
side, his other foot pointing westwards, his head twisted back between
hunched shoulders as if complaining to God about a cruel fate.

Behind him he heard a boy say to his father. 'Oh, Daddy, look at the
poor twisted cripple.'

'Hush,' the father said. 'Be grateful the poor man found such a
brilliant tailor.'

****

The Ultrafidelista view of Negative Feedback
by Andre Jute
Negative feedback is the paradigm of modern electronic design. It is
mother's milk to an electronics engineer. He learns to say '100dB of
NFB,' in his sleep before he finishes his first week at the most humble
polytechnic. At the great institutions the professor of feedback is the
most honoured man in the department. In Massachusetts and Minnesota the
feedback guru is the most honoured man on the entire campus, equal in
stature to the football coach. When a guru of transistor high fidelity
(and some in tubes) says, 'I studied under Ron,' one doesn't have to
ask which Ron, one just knows it is the holy name of the prophet of
feedback from the Midwest.

Before I even finished the design of the KISS 300B it was forcefully
suggested by a wannabe guru that with only 50dB more gain (about seven
times as much as is likely to be in the actual design) I can apply 50dB
of negative feedback to linearize my amplifier.

Negative feedback, shorthanded as NFB, is the instant response of the
audio engineering fraternity to all ills, real, perceived,
non-existent. They don't even ask if there is a problem, they swing the
club of NFB regardless. NFB has become a reflex axiom of mainstream
audio design. An audio engineer with his negative feedback is like a
policeman who runs out into the street with his stick and starts
beating a confession out of the first housewife he sees. The difference
is that the policeman is relieved of duty to await punishment and the
audio engineer gets away with it. In the case of the policeman it is
unacceptable behaviour, in the case of the audio engineer so much the
expected norm that no one except the ultrafidelista notice. I guess
that if one in ten million audio amplifiers does not have negative
feedback added, it will be a lot...

No one asked if my KISS Amp requires linearization. The presumption by
all except those already of the ultrafidelista persuasion was that I
would welcome suggestions about A Good Thing.

In the face of such overwhelming acceptance by qualified engineers, why
do we as ultrafidelista not take the same easy path of negative
feedback? Especially considering that superficially NFB is easy to
understand and apply.

How does negative feedback work?
Negative feedback is simply a negative voltage fed back from the output
to the input amplifying device to offset part of the harmonic
distortion which is present as a positive voltage. It costs nothing
except a loss of gain and a few side effects such as phase shift and
possible instability which are well known in the mathematical
literature and more or less easily guarded against depending on the
level of NFB.

'Wow!' those meeting NFB for the first time will now say, 'Something
for free! I'll grab some of that for my amp.' Hey, I said it, and I am
a professional intellectual, by definition an infinite skeptic. NFB is
a thing of beauty that will draw you in. It is like an electronic
Marxism which admits of no contrary arguments because it has subsumed
them all into The Holy Measurements. To question The Measurements is to
commit heresy. You need to be of strong mind to resist the
blandishments of such a universal panacea and of strong stomach to
withstand the hysterical assaults of the lesser engineers defending
their holy grail. (And when you do get hold of a superior engineer to
explain NFB to you, you need to be high-domed indeed because suddenly
NFB can turn very intricate.)

Unfortunately NFB doesn't come without a price. It levies a cruel
charge on the perceived quality of the sound. Negative feedback is what
gives all those 'blameless' transistor and big PP tube amps their
chillingly unnatural sound.

Then how did NFB come to be such a panacea in amplifier design?
Your guess is as good as mine. Hi-fi design is not prestige work for
engineers, or highly paid. The most talented and best qualified
engineers go into automobiles or military hardware or big construction
projects or computer design. The left-overs design amplifiers in the
time they have to spare from writing up specs for requesting a CE mark
for a new electric kettle. Lemmings storming en masse over a cliff come
to mind; such people don't see the necessity of original thought, or
have the mental equipment for it. The exceptions to this rule are
normally audio enthusiasts in charge of their own small audio
manufactories with niche markets; those who grow larger from this base
follow the mainstream mantra of "mo' NFB give lowa' THD" because the
marketing channels demand it from them if they wish to grow. At this
point they usually cease to offer anything different, only the
exclusivity of a very high price. (I know, because a sub-board I
designed for a supplier to the trade turns up in so many very expensive
amps with so many different big names neatly silkscreened on it... it
strikes me as the sort of detail a real designer, as distinct from a
marketer, would take under his own control.) Those very few makers who
will sell you an ultrafi amp without any NFB operate even tinier shops,
usually one man and a cat, just hanging on.

The mechanism by which NFB wrecks your sound
Negative feedback at first acquaintance sounds good enough to take to
bed and cuddle. It isn't. It isn't even as simple as a superficial
acquaintance may suggest. Follow the steps with me, from the theory as
she is received to what arrives at your brain as music:

1. In theory NFB reduces all harmonic distortion equally, without
discrimination. Strictly in theory it does not reshape harmonic
distortion by reducing the most objectionable third and higher order
odd harmonic distortion to a greater extent than the relatively
harmless 2nd harmonic. Thus NFB at its theoretically most benign is
already useless in terms of psychoacoustics, as will become clear at
point 4. If you disregard psychoacoustics, as many audio engineers do,
NFB is brilliant in reducing total harmonic distortion to a number as
tiny as you want. You just pile on more NFB.

2. In real life, as distinct from simplified theory, NFB adds artifacts
of its own. Remember, it is a loop. The signal starts at the input and
is amplified by devices until it reaches the output. From the output a
part of the signal called the negative feedback is fed back to the
input. Here a loop is completed and the combination, less distorted,
reaches the output again, a part of the combination is fed back,
endlessly. The artifacts we want to consider here are created by the
fed-back residue of harmonic distortions adding to both the fundamental
and the distortions already created by the amplifier, then some portion
of the sum of the original and the feedback distortion is fed back
again and added on, until the ooh-ah bird flies up its own fundament.
It looks marginally less disgusting as a recursive mathematical formula
with lots of nested parenthetical parcels of noise being loaded onto
your music. But it is a monkey on the back of your sound, with a
smaller monkey on the back of the first monkey, a still smaller monkey
on the back of the second monkey, and so on ad infinitum. These
additive artifacts are all higher harmonics and the more dominant ones
are all odd. Suppose, for the sake of simplicity, a superbly designed
ultrafidelista amp with some second harmonic and zero odd harmonics
before NFB. Add NFB and the second harmonic will be lowered but the
recombinant new loop now contains newly added intermodulation effects
between the fundamental and the residual second harmonic, and that is
third harmonic. In the next cycle a small but nasty dose of fifth
harmonic that wasn't there before is added by interaction between the
still residual second harmonic and reduced newly added third harmonic.
In short, the artifacts NFB adds to the distortion mix are all of the
most harmful kind. But, say the proponents of NFB, so what? Every time
the loop cycles the added artifacts are smaller, even if there are more
of them... The whole affair starts to smell of trying to argue with a
Marxist who simply declares any inconvenient truth 'an anomaly'. (If
this sounds like a mess from which you should run a mile, you have come
to the right conclusion. Start running now. It gets worse.)

3. We thus arrive at a situation where distortion has been lowered by
NFB but where the most disturbing odd harmonic distortions are still
present to some measure, with the added disadvantage that new and
extremely disturbing artifacts of higher harmonic distortions have been
created by the very process of using negative feedback to lower
distortion. Regardless of the absolute level of THD, or the volume
setting, the mix of harmonics has been adversely affected and now
includes a higher proportion of third and higher harmonics than before
NFB. Let me say that again: after NFB, third and higher harmonics will
make up a greater part of the distortion than before.

4. Low volume levels perforce accounts for 99 per cent of audiophile
listening because we all have families or neighbours, and we would like
to keep our ears. Unfortunately for the lowest common denominator of
hi-fi designer, the one who specifies NFB as a conditioned response
much like Pavlov's dogs slavered when the bell rang, human physiology
and psycho-acoustic response is such that odd harmonics are
disproportionately more disturbing at lower than at higher listening
levels. This inescapable effect is independent of definition of
'listening level.' At the 110dB in-room SPL (only 14dB louder than an
automatic riveter!) advocated by the already deaf Transient Overload
Elite known on newsgroups as the Borg, this poisonous concoction of
original distortions and NFB recombinant artifacts will be least
disturbing (and soon not heard at all!). At any lower level perceived
interference of this harmonics cocktail with the music will increase in
inverse proportion to the volume level. At low volume levels the
artifacts generated by NFB will by their nature as higher harmonic
distortions be disproportionately far more disturbing. At these normal
listening levels 0.75 per cent of second harmonic distortion may be
below the threshhold of perception for sophisticated listeners, whereas
tiny amounts of third and higher odd harmonic distortions grate.

And they still use Negative Feedback? Are they stupid?
No, they are not stupid. Most of them march to the drum of a cost
accountant on whom we wouldn't spit if he were alight. NFB is as cheap
in money terms as it is expensive in terms of perceived quality of
music. We shall come to those who claim to be sympathetic to
high-fidelity but insist on devices which do not work without NFB, who
have another devious answer. Here, meanwhile, for you to keep in mind,
is a single-sentence summary of a complicated interdisciplinary
argument:

The case against NFB is that for 99 per cent of listening the NFB cure
is worse than the disease.

But surely we don't have to do anything so stupid?
It follows from the argument above that ultrafidelista should choose an
intrinsically linear topology and device which does not require added
negative feedback to 'linearize' the output. The intrinsically linear
device is the thermionic tube in either its triode form or as a pentode
hogtied to work as a triode, which can be a most pleasing alternative
both economically and sonically. The topology is often single-ended
operation, chosen also for several other reasons described elsewhere in
these articles, including KISS; if the chosen topology is push-pull
operation, which is more difficult but far from impossible to arrange
without NFB, operation should be specified as Class A1. Inside the
argued case above lies too the overwhelming reason to accept the
potential small disadvantage that may accompany the preferred topology
in comparison to the discarded alternatives. The disadvantage is of
course the potential for a residual second harmonic that measures high
by transistor or NFB tube standards. (Note the word potential. With a
conservatively designed DHT amp the potential problem should not
arise.)

The ultrafidelista, who are as keen on silent amps as anyone else,
accept this small potential difficulty because it is the lesser evil
compared to NFB. Unbelievers (largely unwashed, according to reports)
sneer that ultrafidelista like this approach because of the 'added
euphonics', which is bow-wow techie talk for the warmth a big chunk of
second harmonic lays on a zero negative feedback single-ended
amplifier. But competent design can easily reduce the level of second
harmonic to below the level of perception without the need for NFB and
its deleterious after-effects. In any event, it is your amplifier. You
paid for it. You have a right to tune it as you please. The key thing
is to get rid of NFB and to understand why you did it.

Can we prove any of this scientifically?
We have already. All of this is the technical subtext to my longtime
contention that what the ultrafidelista hear and love is not a directly
heated triode sound as is claimed by many enthusiasts but a Class A1,
ZNFB sound. (Admittedly, as we have seen above, the right sound is
virtually guaranteed with a ZNFB DHT SE amp of conservative provenance
but may have to be developed the hard way with more economical or
higher-power contenders.) In comparative ABX tests conducted over a
number of years, I found that professional musicians, certified golden
ears, choose the triode-linked Class A1 PP ZNFB EL34 whenever it is
present in the test over all other contenders including SE 300B and
'blameless' high-NFB silicon.

Science also proceeds by pure reason. Ultrafidelista have long doubted
whether what engineers insist we measure (the absolute level of
distortion, THD) predicts success in audio gear. This is the full
circle, because I have just proven by logical, individually uncontested
steps that what matters, once a certain modest level of silence is
assured to an amplifier, is not the absolute level of disharmonics but
their composition. The same proof demonstrates that a more beneficial
distribution follows instantly from doing without NFB.

But transistor amps won't work at all without NFB!
That is not our problem. Those who choose inefficient speakers and
consequently are forced to accept monstrous amps made possible only by
gigadeciBels of NFB, will receive our sympathy - and the music they
deserve.

Engineering hangers-on of transistor attempts at high fidelity, where
the measure of success is vanishing THD rather than sonic hedonism,
pretend to be enthusiasts for NFB. To make it work for them, they have
attempted to change the rules so that we won't hear what their
treasured NFB does to our sound. They sneer that low level listening,
which 99 per cent of us prefer and where NFB does most to wreck the
sound, is 'easy listening' and therefore not permissible. According to
them we should all be forced to listen at the high volume level which
suits NFB amps, which they call 'realistic'. This is a contemptible
circular argument, only too characteristic of a fascist mentality in a
part of the audiophile spectrum which wants to prescribe their arid
vision without regard for our enjoyment.

We can recommend a good tailor to them. It hurts every time you wear
his suit. No pain, no gain, fellers!

In summary
Almost everyone listens at low level most of the time. NFB wrecks
everybody's sound at all levels but most wretchedly at normal listening
levels. We started out with a contemptible circular argument and we
have met another along the way. We can now put both in context:

An 'engineer' who designs an amplifier which does not work perfectly
without negative feedback is like a tailor cutting the suit
incompetently and then demanding that you walk like a cripple to make
it fit, so that everyone can admire the brilliance of your tailor.

Negative feedback is a bodge. That is why it is despicable to the
ultrafidelista.

*******
More Zero Negative Feedback amplifiers at Jute on Amps
http://members.lycos.co.uk/fiultra/JUTE%20ON%20AMPS.htm
The KISS Amp project, which explains much more, is here
http://members.lycos.co.uk/fiultra/The%20KISS%20Amp%20INDEX.htm
and its schematics and transfer curves are here
http://members.lycos.co.uk/fiultra/KISS%20190.htm

********
THE VOLTAGES IN THIS AMP WILL KILL YOU.
GET EXPERIENCED SUPERVISION IF IT IS YOUR FIRST TUBE AMP

All text and illustration is Copyright © Andre Jute 2001, 2004, 2006
and may not be reproduced except in the thread KISS xxx on
rec.audio.tubes

[Stewart Pinkerton]

On Fri, 24 Mar 2006 19:49:18 +0100, "Ruud Broens" >
wrote:

>
>"Stewart Pinkerton" > wrote in message
...
>: On Fri, 24 Mar 2006 17:57:12 +0100, "Ruud Broens" >
>: wrote:
>:
>: >: >: Where's the beef?
>: >: >:
>: >: >they 'beef' is, your banana needs 1K more straightening' than my banana -
>: >: >why keep claiming it is "superior" ?
>: >:
>: >: Because what matters is the output of the *final* circuit - the banana
>: >: is perfectly straight in the opamp, but your tube circuit is still
>: >: bendy.
>: >
>: >yeah, right, as in 0.007 % distortion kinda bendy.
>: >must be what they call 'the scottish bend',
>: >then
>:
>: Be more specific about the tubed circuit you claim has this level of
>: distortion.
>:
>
>eehhrrmm,
>don't think that earlier suggestion of a scottish detective will
>work out,
> after all,
>
>thanks for detecting,
>not even well above noise level,
>lot'sZZ

In other words, you made it up.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

[Ruud Broens]

"Stewart Pinkerton" > wrote in message
...
: On Fri, 24 Mar 2006 19:49:18 +0100, "Ruud Broens" >
: wrote:
:
: >
: >"Stewart Pinkerton" > wrote in message
: ...
: >: On Fri, 24 Mar 2006 17:57:12 +0100, "Ruud Broens" >
: >: wrote:
: >:
: >: >: >: Where's the beef?
: >: >: >:
: >: >: >they 'beef' is, your banana needs 1K more straightening' than my
banana -
: >: >: >why keep claiming it is "superior" ?
: >: >:
: >: >: Because what matters is the output of the *final* circuit - the banana
: >: >: is perfectly straight in the opamp, but your tube circuit is still
: >: >: bendy.
: >: >
: >: >yeah, right, as in 0.007 % distortion kinda bendy.
: >: >must be what they call 'the scottish bend',
: >: >then
: >:
: >: Be more specific about the tubed circuit you claim has this level of
: >: distortion.
: >:
: >
: >eehhrrmm,
: >don't think that earlier suggestion of a scottish detective will
: >work out,
: > after all,
: >
: >thanks for detecting,
: >not even well above noise level,
: >lot'sZZ
:
: In other words, you made it up.
: --
:
: Stewart Pinkerton | Music is Art - Audio is Engineering

as my track record is pretty impressive in that respect,
i can afford this one:

see my upcoming movie: Tweak City
, , starring Kyra

evidently,
Rudy

[Sander deWaal]

"Ruud Broens" > said:


>see my upcoming movie: Tweak City
>, , starring Kyra


Does it perhaps involve aspirins, for when she 'pretends' having a
headache?


I recommend Mundorf aspirins for critical applications ;-)

--

- Never argue with idiots, they drag you down their level and beat you with experience. -

[Ruud Broens]

"Sander deWaal" > wrote in message
...
: "Ruud Broens" > said:
:
:
: >see my upcoming movie: Tweak City
: >, , starring Kyra
:
:
: Does it perhaps involve aspirins, for when she 'pretends' having a
: headache?
:
:
: I recommend Mundorf aspirins for critical applications ;-)
:
: --
:
: - Never argue with idiots, they drag you down their level and beat you with
experience. -

I agree,
that could make of the difference between
knightly & dayly

Ry

[Andre Jute]

Patrick Turner wrote:
> Andre Jute wrote:
>
> > I must say, Wilson, I don't understand why you're getting your knickers
> > in a knot. You're like those bolshies I used to know who claimed that
> > anyone who wasn't willing to kill for "socialism" was only play-acting.
> > Are you really claiming that someone who merely uses the NFB he finds
> > lurking in DHTs can't belong to the club until he repents and uses
> > excessive amounts of loop NFB? Are you really claiming that the use of
> > lots and lots of NFB is a prerequisite for good audio design? Are you
> > really claiming that because a little NFB is a good thing, an unlimited
> > amount must therefore be better, and an infinite amount best of all?
> > Seems a bit immoderate to me, old chap.
>
> You will find yourself arguing at a man who has a head full of solid concrete.
> Trev will never see the whole picture, and has never designed or built any amp in
> the last 30 years.

He's mindless, for sure. All those mindlessly insistent claims that I
said something I didn't say -- right next to the place where I said
exactly the opposite.

> I try not to bother arguing the same old tired BS time after time.
> He just likes hanging out in news groups and Bull****ting.
> He has NEVER once contributed a single article of constructive advice on tubecraft
> at r.a.t.

Doesn't surprise me.

> > Your hysterical belief that I am "against" NFB is the product of your
> > unsophisticated literal-mindedness. There is no reason for NFB to be an
> > act of faith, like an on-off switch. For the record, quite contrary to
> > your silly claims about what I said, I believe the little NFB that
> > occurs naturally in triodes and in certain conservatively sanctioned
> > traditional topologies are A Good Thing. To avoid giving you another
> > apoplectic fit, I shan't repeat what I think of the excessive amounts
> > of NFB required to make transistors work at all.
> >
> > If you think you can write a more compelling argument than I can about
> > the evils of excessive NFB, have at it. But every time I see you, like
> > the other techies you merely kibbitz what better men have written.
>
> I am now doing 845 amps, two per channel for 50 watts each.
> I expect music to be real fine. Damping factor good, noise low,
> bandwidth wide, distortions negligible and maybe I can add 6db of global NFB but
> I doubt any difference due to some **added** NFB will be heard.

You probably won't need the NFB. The biggest problem with 845 is not
deciding how much NFB to use but steeling yourself to let them out of
the door. 845 are God's own tube. I really hesitated when I needed the
space, wondering if I shouldn't keep the simple SET 845 rather than my
Millennium's End SV572-xx amps.

> Trev has never done anything like this and simply doesn't understand.

It's not so difficult to open your mind to new experiences and new
ideas. But first one has to stop being a smartarse, and that I don't
think poor old Trevor can manage.

> With 845, just no need for the 106dB of added NFB used in SS amps.
> I don't care a bit about what Trev says.

I'm fast reaching the same conclusion.

> Patrick Turner.

Andre Jute

[[email protected]]

Stewart Pinkerton wrote:
> On Fri, 24 Mar 2006 17:57:12 +0100, "Ruud Broens" >
> wrote:
>
> >
> >"Stewart Pinkerton" > wrote in message
> ...
> >: On Fri, 24 Mar 2006 12:59:37 +0100, "Ruud Broens" >
> >: wrote:
> >:
> >: >"Arny Krueger" > wrote in message
> >: ...
> >: >: "Ruud Broens" > wrote in message
> >: >:
> >: >:
> >: >: > we've been through this 'linearity contest' before, here.
> >: >: > whereas you define it in terms of current amplification,
> >: >: > i define it in terms of voltage amplification.
> >: >: > as real-world interfacing in audio is with *voltages*,
> >: >: > doesn't seem unreasonable...
> >: >:
> >: >:
> >: >: Negative feedback is generally used to make amplifiers more linear in the
> >: >: voltage domain. It's a highly sucessful strategy. We sent men to the moon,
> >: >: partially based on amplifiers that were linearized with negative feedback.
> >: >:
> >: >: Where's the beef?
> >: >:
> >: >they 'beef' is, your banana needs 1K more straightening' than my banana -
> >: >why keep claiming it is "superior" ?
> >:
> >: Because what matters is the output of the *final* circuit - the banana
> >: is perfectly straight in the opamp, but your tube circuit is still
> >: bendy.
> >
> >yeah, right, as in 0.007 % distortion kinda bendy.
> >must be what they call 'the scottish bend',
> >then
>
> Be more specific about the tubed circuit you claim has this level of
> distortion.
>
> --
>
It's there in the RAT thread Hybrid circuit-CQ something or other.

[Patrick Turner]

>
> > > If you think you can write a more compelling argument than I can about
> > > the evils of excessive NFB, have at it. But every time I see you, like
> > > the other techies you merely kibbitz what better men have written.
> >
> > I am now doing 845 amps, two per channel for 50 watts each.
> > I expect music to be real fine. Damping factor good, noise low,
> > bandwidth wide, distortions negligible and maybe I can add 6db of global NFB but
> > I doubt any difference due to some **added** NFB will be heard.
>
> You probably won't need the NFB. The biggest problem with 845 is not
> deciding how much NFB to use but steeling yourself to let them out of
> the door. 845 are God's own tube. I really hesitated when I needed the
> space, wondering if I shouldn't keep the simple SET 845 rather than my
> Millennium's End SV572-xx amps.

And I am using KR845.....

I think I'll use sepaarate cathode biasing for each 845, tubes and a trioded EL34
driving a 1:1
IST but with a cap shunting the anode to secondary winding to make sure the
HF transfer is near perfect without the leakage inductance having any effect.
Input will be 6SN7, but maybe could be 6SL7 µ follower

>
>
> > Trev has never done anything like this and simply doesn't understand.
>
> It's not so difficult to open your mind to new experiences and new
> ideas. But first one has to stop being a smartarse, and that I don't
> think poor old Trevor can manage.

He regards SET amplification as a form of hi-fi illegitimacy.
Calling people *******s for owning and preferring SE amps to his fav brands of solid
state
makes him look a fool.

>
>
> > With 845, just no need for the 106dB of added NFB used in SS amps.
> > I don't care a bit about what Trev says.
>
> I'm fast reaching the same conclusion.
>
> > Patrick Turner.
>
> Andre Jute

A colleague in Sydney is doing an SE amp with 6 x GM70 for 120 watts.
But it will be switchable to PP......its doable, 5 very good switches are needed, and I
did the OPT design.

Whether the GM70 is better than 845 is unknown.

I like challenges. The OPT for 845 has 3 times the turns that my 300 watt PP amps have,
and the wire is thinner for 845, and my eyes are not getting younger....

Patrick Turner,

[Stewart Pinkerton]

On 24 Mar 2006 14:01:45 -0800, "Andre Jute" > wrote:

>Patrick Turner wrote:

>> I am now doing 845 amps, two per channel for 50 watts each.
>> I expect music to be real fine. Damping factor good, noise low,
>> bandwidth wide, distortions negligible and maybe I can add 6db of global NFB but
>> I doubt any difference due to some **added** NFB will be heard.

Depends on the speakers, the reduced output impedance may be useful.

>You probably won't need the NFB. The biggest problem with 845 is not
>deciding how much NFB to use but steeling yourself to let them out of
>the door. 845 are God's own tube. I really hesitated when I needed the
>space, wondering if I shouldn't keep the simple SET 845 rather than my
>Millennium's End SV572-xx amps.

It's an excellent tube, as tubes go, but of course we've had seventy
years of progress since then.......

>> Trev has never done anything like this and simply doesn't understand.
>
>It's not so difficult to open your mind to new experiences and new
>ideas. But first one has to stop being a smartarse, and that I don't
>think poor old Trevor can manage.

You of course would be the master of this art - except that your arse
is the smartest part of you.

>> With 845, just no need for the 106dB of added NFB used in SS amps.
>> I don't care a bit about what Trev says.

With SS, no need for the massive cost of the output transformer for 50
watts of single-ended tube amplification, plus of course you get much
better linearity than even the mighty 845 can manage. A really good
60-watt SS amp is very easy to implement these days - and you can buy
one for the cost of a pair of those OPTs...............

--

Stewart Pinkerton | Music is Art - Audio is Engineering

Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
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[Arny Krueger]

"Bret Ludwig" > wrote in message
oups.com
> Ruud Broens wrote:
>
> <<snip>>
>
>
>> The opamp is *designed* to use large amounts of
>> linearising
>>> feedback, something that simply isn't an option with
>>> the inherently much lower open-loop gain of tubes.

> Philbrick and Julie were building perfectly proper op
> amps with tubes as early as 1943, but thanks for playing.

Actually, tubed operational amps, especially the early ones (the specific
ones you're mentioning), were horrors. If the noise and drift didn't get
you, the short parts life would.

Operational amplifiers were originally designed as parts for analog
computers. When SS op amps for analog computers became commercial, analog
computer experts sighed a huge sigh of relief. They were stable, reliable,
and quiet.

[John Stewart]

John Deans wrote:

> "Andre Jute" > wrote in message
> ups.com...
> Some meterhead clown demands to know:
> >What's wrong with feedback?<
> and another meterhead clown, on being told by Rudy that:
> >an OPA2604 ... needs a *thousand* times more feedback<
> demands to know:
> >So what?
>
> *****
> It ain't rocket science. Explanation taken from:
> http://members.lycos.co.uk/fiultra/The%20KISS%20Amp%20INDEX.htm
>
> *****
> CATCH-22
> *****
> The customer complained that his new suit didn't fit. 'The sleeves are
> too short,' he said to the tailor.
>
> 'Yes sir,' said the tailor, 'but if you hold your arm just so, at an
> angle as if you're drinking tea with your auntie, it will show just the
> right amount of cuff.'
>
> The customer tried it. The tailor was right! 'But what about the other
> sleeve? It is definitely too short.'
>
> 'Just lower your shoulder, sir. Yes, yes, a little more. Put your foot
> out so you can lower your shoulder a little more still. Bend your knee.
> Yes, that's it. See how beautifully your suitcoat now fits?'
>
> The customer had to admit the tailor was right. 'Wow. But now the leg
> of the pants is all twisted around.'
>
> 'That's easily fixed,' said the tailor. 'Just point your other toe
> westward, sir, and look over your shoulder to where I am holding up the
> hand mirror. See? Doesn't that fit beautifully?'
>
> 'Yes,' the customer said doubtfully, 'but-'
>
> 'Now would sir like to wear his brilliant new suit or shall we wrap
> it?'
>
> The customer was too intimidated to argue. He walked out into the
> street in his new suit, his arm crooked as if he were drinking tea, his
> other shoulder well down over a bent knee with his foot out to the
> side, his other foot pointing westwards, his head twisted back between
> hunched shoulders as if complaining to God about a cruel fate.
>
> Behind him he heard a boy say to his father. 'Oh, Daddy, look at the
> poor twisted cripple.'
>
> 'Hush,' the father said. 'Be grateful the poor man found such a
> brilliant tailor.'
>
> ****
>
> The Ultrafidelista view of Negative Feedback
> by Andre Jute
> Negative feedback is the paradigm of modern electronic design. It is
> mother's milk to an electronics engineer. He learns to say '100dB of
> NFB,' in his sleep before he finishes his first week at the most humble
> polytechnic. At the great institutions the professor of feedback is the
> most honoured man in the department. In Massachusetts and Minnesota the
> feedback guru is the most honoured man on the entire campus, equal in
> stature to the football coach. When a guru of transistor high fidelity
> (and some in tubes) says, 'I studied under Ron,' one doesn't have to
> ask which Ron, one just knows it is the holy name of the prophet of
> feedback from the Midwest.
>
> Before I even finished the design of the KISS 300B it was forcefully
> suggested by a wannabe guru that with only 50dB more gain (about seven
> times as much as is likely to be in the actual design) I can apply 50dB
> of negative feedback to linearize my amplifier.
>
> Negative feedback, shorthanded as NFB, is the instant response of the
> audio engineering fraternity to all ills, real, perceived,
> non-existent. They don't even ask if there is a problem, they swing the
> club of NFB regardless. NFB has become a reflex axiom of mainstream
> audio design. An audio engineer with his negative feedback is like a
> policeman who runs out into the street with his stick and starts
> beating a confession out of the first housewife he sees. The difference
> is that the policeman is relieved of duty to await punishment and the
> audio engineer gets away with it. In the case of the policeman it is
> unacceptable behaviour, in the case of the audio engineer so much the
> expected norm that no one except the ultrafidelista notice. I guess
> that if one in ten million audio amplifiers does not have negative
> feedback added, it will be a lot...
>
> No one asked if my KISS Amp requires linearization. The presumption by
> all except those already of the ultrafidelista persuasion was that I
> would welcome suggestions about A Good Thing.
>
> In the face of such overwhelming acceptance by qualified engineers, why
> do we as ultrafidelista not take the same easy path of negative
> feedback? Especially considering that superficially NFB is easy to
> understand and apply.
>
> How does negative feedback work?
> Negative feedback is simply a negative voltage fed back from the output
> to the input amplifying device to offset part of the harmonic
> distortion which is present as a positive voltage. It costs nothing
> except a loss of gain and a few side effects such as phase shift and
> possible instability which are well known in the mathematical
> literature and more or less easily guarded against depending on the
> level of NFB.
>
> 'Wow!' those meeting NFB for the first time will now say, 'Something
> for free! I'll grab some of that for my amp.' Hey, I said it, and I am
> a professional intellectual, by definition an infinite skeptic. NFB is
> a thing of beauty that will draw you in. It is like an electronic
> Marxism which admits of no contrary arguments because it has subsumed
> them all into The Holy Measurements. To question The Measurements is to
> commit heresy. You need to be of strong mind to resist the
> blandishments of such a universal panacea and of strong stomach to
> withstand the hysterical assaults of the lesser engineers defending
> their holy grail. (And when you do get hold of a superior engineer to
> explain NFB to you, you need to be high-domed indeed because suddenly
> NFB can turn very intricate.)
>
> Unfortunately NFB doesn't come without a price. It levies a cruel
> charge on the perceived quality of the sound. Negative feedback is what
> gives all those 'blameless' transistor and big PP tube amps their
> chillingly unnatural sound.
>
> Then how did NFB come to be such a panacea in amplifier design?
> Your guess is as good as mine. Hi-fi design is not prestige work for
> engineers, or highly paid. The most talented and best qualified
> engineers go into automobiles or military hardware or big construction
> projects or computer design. The left-overs design amplifiers in the
> time they have to spare from writing up specs for requesting a CE mark
> for a new electric kettle. Lemmings storming en masse over a cliff come
> to mind; such people don't see the necessity of original thought, or
> have the mental equipment for it. The exceptions to this rule are
> normally audio enthusiasts in charge of their own small audio
> manufactories with niche markets; those who grow larger from this base
> follow the mainstream mantra of "mo' NFB give lowa' THD" because the
> marketing channels demand it from them if they wish to grow. At this
> point they usually cease to offer anything different, only the
> exclusivity of a very high price. (I know, because a sub-board I
> designed for a supplier to the trade turns up in so many very expensive
> amps with so many different big names neatly silkscreened on it... it
> strikes me as the sort of detail a real designer, as distinct from a
> marketer, would take under his own control.) Those very few makers who
> will sell you an ultrafi amp without any NFB operate even tinier shops,
> usually one man and a cat, just hanging on.
>
> The mechanism by which NFB wrecks your sound
> Negative feedback at first acquaintance sounds good enough to take to
> bed and cuddle. It isn't. It isn't even as simple as a superficial
> acquaintance may suggest. Follow the steps with me, from the theory as
> she is received to what arrives at your brain as music:
>
> 1. In theory NFB reduces all harmonic distortion equally, without
> discrimination. Strictly in theory it does not reshape harmonic
> distortion by reducing the most objectionable third and higher order
> odd harmonic distortion to a greater extent than the relatively
> harmless 2nd harmonic. Thus NFB at its theoretically most benign is
> already useless in terms of psychoacoustics, as will become clear at
> point 4. If you disregard psychoacoustics, as many audio engineers do,
> NFB is brilliant in reducing total harmonic distortion to a number as
> tiny as you want. You just pile on more NFB.
>
> 2. In real life, as distinct from simplified theory, NFB adds artifacts
> of its own. Remember, it is a loop. The signal starts at the input and
> is amplified by devices until it reaches the output. From the output a
> part of the signal called the negative feedback is fed back to the
> input. Here a loop is completed and the combination, less distorted,
> reaches the output again, a part of the combination is fed back,
> endlessly. The artifacts we want to consider here are created by the
> fed-back residue of harmonic distortions adding to both the fundamental
> and the distortions already created by the amplifier, then some portion
> of the sum of the original and the feedback distortion is fed back
> again and added on, until the ooh-ah bird flies up its own fundament.
> It looks marginally less disgusting as a recursive mathematical formula
> with lots of nested parenthetical parcels of noise being loaded onto
> your music. But it is a monkey on the back of your sound, with a
> smaller monkey on the back of the first monkey, a still smaller monkey
> on the back of the second monkey, and so on ad infinitum. These
> additive artifacts are all higher harmonics and the more dominant ones
> are all odd. Suppose, for the sake of simplicity, a superbly designed
> ultrafidelista amp with some second harmonic and zero odd harmonics
> before NFB. Add NFB and the second harmonic will be lowered but the
> recombinant new loop now contains newly added intermodulation effects
> between the fundamental and the residual second harmonic, and that is
> third harmonic. In the next cycle a small but nasty dose of fifth
> harmonic that wasn't there before is added by interaction between the
> still residual second harmonic and reduced newly added third harmonic.
> In short, the artifacts NFB adds to the distortion mix are all of the
> most harmful kind. But, say the proponents of NFB, so what? Every time
> the loop cycles the added artifacts are smaller, even if there are more
> of them... The whole affair starts to smell of trying to argue with a
> Marxist who simply declares any inconvenient truth 'an anomaly'. (If
> this sounds like a mess from which you should run a mile, you have come
> to the right conclusion. Start running now. It gets worse.)
>
> 3. We thus arrive at a situation where distortion has been lowered by
> NFB but where the most disturbing odd harmonic distortions are still
> present to some measure, with the added disadvantage that new and
> extremely disturbing artifacts of higher harmonic distortions have been
> created by the very process of using negative feedback to lower
> distortion. Regardless of the absolute level of THD, or the volume
> setting, the mix of harmonics has been adversely affected and now
> includes a higher proportion of third and higher harmonics than before
> NFB. Let me say that again: after NFB, third and higher harmonics will
> make up a greater part of the distortion than before.
>
> 4. Low volume levels perforce accounts for 99 per cent of audiophile
> listening because we all have families or neighbours, and we would like
> to keep our ears. Unfortunately for the lowest common denominator of
> hi-fi designer, the one who specifies NFB as a conditioned response
> much like Pavlov's dogs slavered when the bell rang, human physiology
> and psycho-acoustic response is such that odd harmonics are
> disproportionately more disturbing at lower than at higher listening
> levels. This inescapable effect is independent of definition of
> 'listening level.' At the 110dB in-room SPL (only 14dB louder than an
> automatic riveter!) advocated by the already deaf Transient Overload
> Elite known on newsgroups as the Borg, this poisonous concoction of
> original distortions and NFB recombinant artifacts will be least
> disturbing (and soon not heard at all!). At any lower level perceived
> interference of this harmonics cocktail with the music will increase in
> inverse proportion to the volume level. At low volume levels the
> artifacts generated by NFB will by their nature as higher harmonic
> distortions be disproportionately far more disturbing. At these normal
> listening levels 0.75 per cent of second harmonic distortion may be
> below the threshhold of perception for sophisticated listeners, whereas
> tiny amounts of third and higher odd harmonic distortions grate.
>
> And they still use Negative Feedback? Are they stupid?
> No, they are not stupid. Most of them march to the drum of a cost
> accountant on whom we wouldn't spit if he were alight. NFB is as cheap
> in money terms as it is expensive in terms of perceived quality of
> music. We shall come to those who claim to be sympathetic to
> high-fidelity but insist on devices which do not work without NFB, who
> have another devious answer. Here, meanwhile, for you to keep in mind,
> is a single-sentence summary of a complicated interdisciplinary
> argument:
>
> The case against NFB is that for 99 per cent of listening the NFB cure
> is worse than the disease.
>
> But surely we don't have to do anything so stupid?
> It follows from the argument above that ultrafidelista should choose an
> intrinsically linear topology and device which does not require added
> negative feedback to 'linearize' the output. The intrinsically linear
> device is the thermionic tube in either its triode form or as a pentode
> hogtied to work as a triode, which can be a most pleasing alternative
> both economically and sonically. The topology is often single-ended
> operation, chosen also for several other reasons described elsewhere in
> these articles, including KISS; if the chosen topology is push-pull
> operation, which is more difficult but far from impossible to arrange
> without NFB, operation should be specified as Class A1. Inside the
> argued case above lies too the overwhelming reason to accept the
> potential small disadvantage that may accompany the preferred topology
> in comparison to the discarded alternatives. The disadvantage is of
> course the potential for a residual second harmonic that measures high
> by transistor or NFB tube standards. (Note the word potential. With a
> conservatively designed DHT amp the potential problem should not
> arise.)
>
> The ultrafidelista, who are as keen on silent amps as anyone else,
> accept this small potential difficulty because it is the lesser evil
> compared to NFB. Unbelievers (largely unwashed, according to reports)
> sneer that ultrafidelista like this approach because of the 'added
> euphonics', which is bow-wow techie talk for the warmth a big chunk of
> second harmonic lays on a zero negative feedback single-ended
> amplifier. But competent design can easily reduce the level of second
> harmonic to below the level of perception without the need for NFB and
> its deleterious after-effects. In any event, it is your amplifier. You
> paid for it. You have a right to tune it as you please. The key thing
> is to get rid of NFB and to understand why you did it.
>
> Can we prove any of this scientifically?
> We have already. All of this is the technical subtext to my longtime
> contention that what the ultrafidelista hear and love is not a directly
> heated triode sound as is claimed by many enthusiasts but a Class A1,
> ZNFB sound. (Admittedly, as we have seen above, the right sound is
> virtually guaranteed with a ZNFB DHT SE amp of conservative provenance
> but may have to be developed the hard way with more economical or
> higher-power contenders.) In comparative ABX tests conducted over a
> number of years, I found that professional musicians, certified golden
> ears, choose the triode-linked Class A1 PP ZNFB EL34 whenever it is
> present in the test over all other contenders including SE 300B and
> 'blameless' high-NFB silicon.
>
> Science also proceeds by pure reason. Ultrafidelista have long doubted
> whether what engineers insist we measure (the absolute level of
> distortion, THD) predicts success in audio gear. This is the full
> circle, because I have just proven by logical, individually uncontested
> steps that what matters, once a certain modest level of silence is
> assured to an amplifier, is not the absolute level of disharmonics but
> their composition. The same proof demonstrates that a more beneficial
> distribution follows instantly from doing without NFB.
>
> But transistor amps won't work at all without NFB!
> That is not our problem. Those who choose inefficient speakers and
> consequently are forced to accept monstrous amps made possible only by
> gigadeciBels of NFB, will receive our sympathy - and the music they
> deserve.
>
> Engineering hangers-on of transistor attempts at high fidelity, where
> the measure of success is vanishing THD rather than sonic hedonism,
> pretend to be enthusiasts for NFB. To make it work for them, they have
> attempted to change the rules so that we won't hear what their
> treasured NFB does to our sound. They sneer that low level listening,
> which 99 per cent of us prefer and where NFB does most to wreck the
> sound, is 'easy listening' and therefore not permissible. According to
> them we should all be forced to listen at the high volume level which
> suits NFB amps, which they call 'realistic'. This is a contemptible
> circular argument, only too characteristic of a fascist mentality in a
> part of the audiophile spectrum which wants to prescribe their arid
> vision without regard for our enjoyment.
>
> We can recommend a good tailor to them. It hurts every time you wear
> his suit. No pain, no gain, fellers!
>
> In summary
> Almost everyone listens at low level most of the time. NFB wrecks
> everybody's sound at all levels but most wretchedly at normal listening
> levels. We started out with a contemptible circular argument and we
> have met another along the way. We can now put both in context:
>
> An 'engineer' who designs an amplifier which does not work perfectly
> without negative feedback is like a tailor cutting the suit
> incompetently and then demanding that you walk like a cripple to make
> it fit, so that everyone can admire the brilliance of your tailor.
>
> Negative feedback is a bodge. That is why it is despicable to the
> ultrafidelista.
>
> *******
> More Zero Negative Feedback amplifiers at Jute on Amps
> http://members.lycos.co.uk/fiultra/JUTE%20ON%20AMPS.htm
> The KISS Amp project, which explains much more, is here
> http://members.lycos.co.uk/fiultra/The%20KISS%20Amp%20INDEX.htm
> and its schematics and transfer curves are here
> http://members.lycos.co.uk/fiultra/KISS%20190.htm
>
> ********
> THE VOLTAGES IN THIS AMP WILL KILL YOU.
> GET EXPERIENCED SUPERVISION IF IT IS YOUR FIRST TUBE AMP
>
> All text and illustration is Copyright © Andre Jute 2001, 2004, 2006
> and may not be reproduced except in the thread KISS xxx on
> rec.audio.tubes

Bunk. JLS

[John Stewart]

John Deans wrote:

> "Andre Jute" > wrote in message
> ups.com...
> Some meterhead clown demands to know:
> >What's wrong with feedback?<
> and another meterhead clown, on being told by Rudy that:
> >an OPA2604 ... needs a *thousand* times more feedback<
> demands to know:
> >So what?
>
> *****
> It ain't rocket science. Explanation taken from:
> http://members.lycos.co.uk/fiultra/The%20KISS%20Amp%20INDEX.htm
>
> *****
> CATCH-22
> *****
> The customer complained that his new suit didn't fit. 'The sleeves are
> too short,' he said to the tailor.
>
> 'Yes sir,' said the tailor, 'but if you hold your arm just so, at an
> angle as if you're drinking tea with your auntie, it will show just the
> right amount of cuff.'
>
> The customer tried it. The tailor was right! 'But what about the other
> sleeve? It is definitely too short.'
>
> 'Just lower your shoulder, sir. Yes, yes, a little more. Put your foot
> out so you can lower your shoulder a little more still. Bend your knee.
> Yes, that's it. See how beautifully your suitcoat now fits?'
>
> The customer had to admit the tailor was right. 'Wow. But now the leg
> of the pants is all twisted around.'
>
> 'That's easily fixed,' said the tailor. 'Just point your other toe
> westward, sir, and look over your shoulder to where I am holding up the
> hand mirror. See? Doesn't that fit beautifully?'
>
> 'Yes,' the customer said doubtfully, 'but-'
>
> 'Now would sir like to wear his brilliant new suit or shall we wrap
> it?'
>
> The customer was too intimidated to argue. He walked out into the
> street in his new suit, his arm crooked as if he were drinking tea, his
> other shoulder well down over a bent knee with his foot out to the
> side, his other foot pointing westwards, his head twisted back between
> hunched shoulders as if complaining to God about a cruel fate.
>
> Behind him he heard a boy say to his father. 'Oh, Daddy, look at the
> poor twisted cripple.'
>
> 'Hush,' the father said. 'Be grateful the poor man found such a
> brilliant tailor.'
>
> ****
>
> The Ultrafidelista view of Negative Feedback
> by Andre Jute
> Negative feedback is the paradigm of modern electronic design. It is
> mother's milk to an electronics engineer. He learns to say '100dB of
> NFB,' in his sleep before he finishes his first week at the most humble
> polytechnic. At the great institutions the professor of feedback is the
> most honoured man in the department. In Massachusetts and Minnesota the
> feedback guru is the most honoured man on the entire campus, equal in
> stature to the football coach. When a guru of transistor high fidelity
> (and some in tubes) says, 'I studied under Ron,' one doesn't have to
> ask which Ron, one just knows it is the holy name of the prophet of
> feedback from the Midwest.
>
> Before I even finished the design of the KISS 300B it was forcefully
> suggested by a wannabe guru that with only 50dB more gain (about seven
> times as much as is likely to be in the actual design) I can apply 50dB
> of negative feedback to linearize my amplifier.
>
> Negative feedback, shorthanded as NFB, is the instant response of the
> audio engineering fraternity to all ills, real, perceived,
> non-existent. They don't even ask if there is a problem, they swing the
> club of NFB regardless. NFB has become a reflex axiom of mainstream
> audio design. An audio engineer with his negative feedback is like a
> policeman who runs out into the street with his stick and starts
> beating a confession out of the first housewife he sees. The difference
> is that the policeman is relieved of duty to await punishment and the
> audio engineer gets away with it. In the case of the policeman it is
> unacceptable behaviour, in the case of the audio engineer so much the
> expected norm that no one except the ultrafidelista notice. I guess
> that if one in ten million audio amplifiers does not have negative
> feedback added, it will be a lot...
>
> No one asked if my KISS Amp requires linearization. The presumption by
> all except those already of the ultrafidelista persuasion was that I
> would welcome suggestions about A Good Thing.
>
> In the face of such overwhelming acceptance by qualified engineers, why
> do we as ultrafidelista not take the same easy path of negative
> feedback? Especially considering that superficially NFB is easy to
> understand and apply.
>
> How does negative feedback work?
> Negative feedback is simply a negative voltage fed back from the output
> to the input amplifying device to offset part of the harmonic
> distortion which is present as a positive voltage. It costs nothing
> except a loss of gain and a few side effects such as phase shift and
> possible instability which are well known in the mathematical
> literature and more or less easily guarded against depending on the
> level of NFB.
>
> 'Wow!' those meeting NFB for the first time will now say, 'Something
> for free! I'll grab some of that for my amp.' Hey, I said it, and I am
> a professional intellectual, by definition an infinite skeptic. NFB is
> a thing of beauty that will draw you in. It is like an electronic
> Marxism which admits of no contrary arguments because it has subsumed
> them all into The Holy Measurements. To question The Measurements is to
> commit heresy. You need to be of strong mind to resist the
> blandishments of such a universal panacea and of strong stomach to
> withstand the hysterical assaults of the lesser engineers defending
> their holy grail. (And when you do get hold of a superior engineer to
> explain NFB to you, you need to be high-domed indeed because suddenly
> NFB can turn very intricate.)
>
> Unfortunately NFB doesn't come without a price. It levies a cruel
> charge on the perceived quality of the sound. Negative feedback is what
> gives all those 'blameless' transistor and big PP tube amps their
> chillingly unnatural sound.
>
> Then how did NFB come to be such a panacea in amplifier design?
> Your guess is as good as mine. Hi-fi design is not prestige work for
> engineers, or highly paid. The most talented and best qualified
> engineers go into automobiles or military hardware or big construction
> projects or computer design. The left-overs design amplifiers in the
> time they have to spare from writing up specs for requesting a CE mark
> for a new electric kettle. Lemmings storming en masse over a cliff come
> to mind; such people don't see the necessity of original thought, or
> have the mental equipment for it. The exceptions to this rule are
> normally audio enthusiasts in charge of their own small audio
> manufactories with niche markets; those who grow larger from this base
> follow the mainstream mantra of "mo' NFB give lowa' THD" because the
> marketing channels demand it from them if they wish to grow. At this
> point they usually cease to offer anything different, only the
> exclusivity of a very high price. (I know, because a sub-board I
> designed for a supplier to the trade turns up in so many very expensive
> amps with so many different big names neatly silkscreened on it... it
> strikes me as the sort of detail a real designer, as distinct from a
> marketer, would take under his own control.) Those very few makers who
> will sell you an ultrafi amp without any NFB operate even tinier shops,
> usually one man and a cat, just hanging on.
>
> The mechanism by which NFB wrecks your sound
> Negative feedback at first acquaintance sounds good enough to take to
> bed and cuddle. It isn't. It isn't even as simple as a superficial
> acquaintance may suggest. Follow the steps with me, from the theory as
> she is received to what arrives at your brain as music:
>
> 1. In theory NFB reduces all harmonic distortion equally, without
> discrimination. Strictly in theory it does not reshape harmonic
> distortion by reducing the most objectionable third and higher order
> odd harmonic distortion to a greater extent than the relatively
> harmless 2nd harmonic. Thus NFB at its theoretically most benign is
> already useless in terms of psychoacoustics, as will become clear at
> point 4. If you disregard psychoacoustics, as many audio engineers do,
> NFB is brilliant in reducing total harmonic distortion to a number as
> tiny as you want. You just pile on more NFB.
>
> 2. In real life, as distinct from simplified theory, NFB adds artifacts
> of its own. Remember, it is a loop. The signal starts at the input and
> is amplified by devices until it reaches the output. From the output a
> part of the signal called the negative feedback is fed back to the
> input. Here a loop is completed and the combination, less distorted,
> reaches the output again, a part of the combination is fed back,
> endlessly. The artifacts we want to consider here are created by the
> fed-back residue of harmonic distortions adding to both the fundamental
> and the distortions already created by the amplifier, then some portion
> of the sum of the original and the feedback distortion is fed back
> again and added on, until the ooh-ah bird flies up its own fundament.
> It looks marginally less disgusting as a recursive mathematical formula
> with lots of nested parenthetical parcels of noise being loaded onto
> your music. But it is a monkey on the back of your sound, with a
> smaller monkey on the back of the first monkey, a still smaller monkey
> on the back of the second monkey, and so on ad infinitum. These
> additive artifacts are all higher harmonics and the more dominant ones
> are all odd. Suppose, for the sake of simplicity, a superbly designed
> ultrafidelista amp with some second harmonic and zero odd harmonics
> before NFB. Add NFB and the second harmonic will be lowered but the
> recombinant new loop now contains newly added intermodulation effects
> between the fundamental and the residual second harmonic, and that is
> third harmonic. In the next cycle a small but nasty dose of fifth
> harmonic that wasn't there before is added by interaction between the
> still residual second harmonic and reduced newly added third harmonic.
> In short, the artifacts NFB adds to the distortion mix are all of the
> most harmful kind. But, say the proponents of NFB, so what? Every time
> the loop cycles the added artifacts are smaller, even if there are more
> of them... The whole affair starts to smell of trying to argue with a
> Marxist who simply declares any inconvenient truth 'an anomaly'. (If
> this sounds like a mess from which you should run a mile, you have come
> to the right conclusion. Start running now. It gets worse.)
>
> 3. We thus arrive at a situation where distortion has been lowered by
> NFB but where the most disturbing odd harmonic distortions are still
> present to some measure, with the added disadvantage that new and
> extremely disturbing artifacts of higher harmonic distortions have been
> created by the very process of using negative feedback to lower
> distortion. Regardless of the absolute level of THD, or the volume
> setting, the mix of harmonics has been adversely affected and now
> includes a higher proportion of third and higher harmonics than before
> NFB. Let me say that again: after NFB, third and higher harmonics will
> make up a greater part of the distortion than before.
>
> 4. Low volume levels perforce accounts for 99 per cent of audiophile
> listening because we all have families or neighbours, and we would like
> to keep our ears. Unfortunately for the lowest common denominator of
> hi-fi designer, the one who specifies NFB as a conditioned response
> much like Pavlov's dogs slavered when the bell rang, human physiology
> and psycho-acoustic response is such that odd harmonics are
> disproportionately more disturbing at lower than at higher listening
> levels. This inescapable effect is independent of definition of
> 'listening level.' At the 110dB in-room SPL (only 14dB louder than an
> automatic riveter!) advocated by the already deaf Transient Overload
> Elite known on newsgroups as the Borg, this poisonous concoction of
> original distortions and NFB recombinant artifacts will be least
> disturbing (and soon not heard at all!). At any lower level perceived
> interference of this harmonics cocktail with the music will increase in
> inverse proportion to the volume level. At low volume levels the
> artifacts generated by NFB will by their nature as higher harmonic
> distortions be disproportionately far more disturbing. At these normal
> listening levels 0.75 per cent of second harmonic distortion may be
> below the threshhold of perception for sophisticated listeners, whereas
> tiny amounts of third and higher odd harmonic distortions grate.
>
> And they still use Negative Feedback? Are they stupid?
> No, they are not stupid. Most of them march to the drum of a cost
> accountant on whom we wouldn't spit if he were alight. NFB is as cheap
> in money terms as it is expensive in terms of perceived quality of
> music. We shall come to those who claim to be sympathetic to
> high-fidelity but insist on devices which do not work without NFB, who
> have another devious answer. Here, meanwhile, for you to keep in mind,
> is a single-sentence summary of a complicated interdisciplinary
> argument:
>
> The case against NFB is that for 99 per cent of listening the NFB cure
> is worse than the disease.
>
> But surely we don't have to do anything so stupid?
> It follows from the argument above that ultrafidelista should choose an
> intrinsically linear topology and device which does not require added
> negative feedback to 'linearize' the output. The intrinsically linear
> device is the thermionic tube in either its triode form or as a pentode
> hogtied to work as a triode, which can be a most pleasing alternative
> both economically and sonically. The topology is often single-ended
> operation, chosen also for several other reasons described elsewhere in
> these articles, including KISS; if the chosen topology is push-pull
> operation, which is more difficult but far from impossible to arrange
> without NFB, operation should be specified as Class A1. Inside the
> argued case above lies too the overwhelming reason to accept the
> potential small disadvantage that may accompany the preferred topology
> in comparison to the discarded alternatives. The disadvantage is of
> course the potential for a residual second harmonic that measures high
> by transistor or NFB tube standards. (Note the word potential. With a
> conservatively designed DHT amp the potential problem should not
> arise.)
>
> The ultrafidelista, who are as keen on silent amps as anyone else,
> accept this small potential difficulty because it is the lesser evil
> compared to NFB. Unbelievers (largely unwashed, according to reports)
> sneer that ultrafidelista like this approach because of the 'added
> euphonics', which is bow-wow techie talk for the warmth a big chunk of
> second harmonic lays on a zero negative feedback single-ended
> amplifier. But competent design can easily reduce the level of second
> harmonic to below the level of perception without the need for NFB and
> its deleterious after-effects. In any event, it is your amplifier. You
> paid for it. You have a right to tune it as you please. The key thing
> is to get rid of NFB and to understand why you did it.
>
> Can we prove any of this scientifically?
> We have already. All of this is the technical subtext to my longtime
> contention that what the ultrafidelista hear and love is not a directly
> heated triode sound as is claimed by many enthusiasts but a Class A1,
> ZNFB sound. (Admittedly, as we have seen above, the right sound is
> virtually guaranteed with a ZNFB DHT SE amp of conservative provenance
> but may have to be developed the hard way with more economical or
> higher-power contenders.) In comparative ABX tests conducted over a
> number of years, I found that professional musicians, certified golden
> ears, choose the triode-linked Class A1 PP ZNFB EL34 whenever it is
> present in the test over all other contenders including SE 300B and
> 'blameless' high-NFB silicon.
>
> Science also proceeds by pure reason. Ultrafidelista have long doubted
> whether what engineers insist we measure (the absolute level of
> distortion, THD) predicts success in audio gear. This is the full
> circle, because I have just proven by logical, individually uncontested
> steps that what matters, once a certain modest level of silence is
> assured to an amplifier, is not the absolute level of disharmonics but
> their composition. The same proof demonstrates that a more beneficial
> distribution follows instantly from doing without NFB.
>
> But transistor amps won't work at all without NFB!
> That is not our problem. Those who choose inefficient speakers and
> consequently are forced to accept monstrous amps made possible only by
> gigadeciBels of NFB, will receive our sympathy - and the music they
> deserve.
>
> Engineering hangers-on of transistor attempts at high fidelity, where
> the measure of success is vanishing THD rather than sonic hedonism,
> pretend to be enthusiasts for NFB. To make it work for them, they have
> attempted to change the rules so that we won't hear what their
> treasured NFB does to our sound. They sneer that low level listening,
> which 99 per cent of us prefer and where NFB does most to wreck the
> sound, is 'easy listening' and therefore not permissible. According to
> them we should all be forced to listen at the high volume level which
> suits NFB amps, which they call 'realistic'. This is a contemptible
> circular argument, only too characteristic of a fascist mentality in a
> part of the audiophile spectrum which wants to prescribe their arid
> vision without regard for our enjoyment.
>
> We can recommend a good tailor to them. It hurts every time you wear
> his suit. No pain, no gain, fellers!
>
> In summary
> Almost everyone listens at low level most of the time. NFB wrecks
> everybody's sound at all levels but most wretchedly at normal listening
> levels. We started out with a contemptible circular argument and we
> have met another along the way. We can now put both in context:
>
> An 'engineer' who designs an amplifier which does not work perfectly
> without negative feedback is like a tailor cutting the suit
> incompetently and then demanding that you walk like a cripple to make
> it fit, so that everyone can admire the brilliance of your tailor.
>
> Negative feedback is a bodge. That is why it is despicable to the
> ultrafidelista.
>
> *******
> More Zero Negative Feedback amplifiers at Jute on Amps
> http://members.lycos.co.uk/fiultra/JUTE%20ON%20AMPS.htm
> The KISS Amp project, which explains much more, is here
> http://members.lycos.co.uk/fiultra/The%20KISS%20Amp%20INDEX.htm
> and its schematics and transfer curves are here
> http://members.lycos.co.uk/fiultra/KISS%20190.htm
>
> ********
> THE VOLTAGES IN THIS AMP WILL KILL YOU.
> GET EXPERIENCED SUPERVISION IF IT IS YOUR FIRST TUBE AMP
>
> All text and illustration is Copyright © Andre Jute 2001, 2004, 2006
> and may not be reproduced except in the thread KISS xxx on
> rec.audio.tubes

Bunk. JLS

[Trevor Wilson]

"Andre Jute" > wrote in message
oups.com...
> Trevor Wilson wrote:
>>Incorrect and innappropriate application
>> of NFB can damage an amplifier's performance.
>
> Now you're getting it, sonny.

**Then say so. Stop telling half-truths. There is NOTHING wrong with NFB, as
long as it is appropriately applied.

Next, try not to describe as a liar
> anyone who doesn't instantly subscribe to your fanatical faith in Blow
> Jobs from Transvestites (BJTs) and soon the rest of us might take you
> seriously.

**I only tell it like it is.

Here are a few of your lies (some of which you have backtracked on):

"Negative feedback, shorthanded as NFB, is the instant response of the audio
engineering fraternity to all ills, real, perceived, non-existent."

"How does negative feedback work?
Negative feedback is simply a negative voltage fed back from the output to
the input amplifying device to offset part of the harmonic distortion which
is present as a positive voltage. It costs nothing except a loss of gain and
a few side effects such as phase shift and possible instability which are
well known in the mathematical literature and more or less easily guarded
against depending on the level of NFB."

"Negative feedback is what gives all those 'blameless' transistor and big
PP tube amps their chillingly unnatural sound."

"(I know, because a sub-board I designed for a supplier to the trade turns
up in so many very expensive amps with so many different big names neatly
silkscreened on it..."

" Suppose, for the sake of simplicity, a superbly designed ultrafidelista
amp with some second harmonic and zero odd harmonics before NFB."

"Let me say that again: after NFB, third and higher harmonics will make up a
greater part of the distortion than before."

"Low volume levels perforce accounts for 99 per cent of audiophile listening
because we all have families or neighbours, and we would like to keep our
ears."

"And they still use Negative Feedback?"

"The case against NFB is that for 99 per cent of listening the NFB cure is
worse than the disease."

"It follows from the argument above that ultrafidelista should choose an
intrinsically linear topology and device which does not require added
negative feedback to 'linearize' the output."

"The intrinsically linear device is the thermionic tube in either its triode
form or as a pentode hogtied to work as a triode, which can be a most
pleasing alternative both economically and sonically."

"In comparative ABX tests conducted over a number of years, I found that
professional musicians, certified golden ears, choose the triode-linked
Class A1 PP ZNFB EL34 whenever it is present in the test over all other
contenders including SE 300B and 'blameless' high-NFB silicon."

"But transistor amps won't work at all without NFB!"

"Engineering hangers-on of transistor attempts at high fidelity, where the
measure of success is vanishing THD rather than sonic hedonism, pretend to
be enthusiasts for NFB."

"They sneer that low level listening, which 99 per cent of us prefer"

"According to them we should all be forced to listen at the high volume
level which suits NFB amps, which they call 'realistic'."

"This is a contemptible circular argument, only too characteristic of a
fascist mentality in a part of the audiophile spectrum which wants to
prescribe their arid vision without regard for our enjoyment."

"Almost everyone listens at low level most of the time."

"Negative feedback is a bodge."


Would you care to amend these lies and state PRECISELY what you mean?


--
Trevor Wilson
www.rageaudio.com.au

[Patrick Turner]

All I hear from Oinkerton is "Oink....oink oink oink......squeal, oink...."

I doubt he makes any thing.

Patrick Turner.







Stewart Pinkerton wrote:

> On 24 Mar 2006 14:01:45 -0800, "Andre Jute" > wrote:
>
> >Patrick Turner wrote:
>
> >> I am now doing 845 amps, two per channel for 50 watts each.
> >> I expect music to be real fine. Damping factor good, noise low,
> >> bandwidth wide, distortions negligible and maybe I can add 6db of global NFB but
> >> I doubt any difference due to some **added** NFB will be heard.
>
> Depends on the speakers, the reduced output impedance may be useful.
>
> >You probably won't need the NFB. The biggest problem with 845 is not
> >deciding how much NFB to use but steeling yourself to let them out of
> >the door. 845 are God's own tube. I really hesitated when I needed the
> >space, wondering if I shouldn't keep the simple SET 845 rather than my
> >Millennium's End SV572-xx amps.
>
> It's an excellent tube, as tubes go, but of course we've had seventy
> years of progress since then.......
>
> >> Trev has never done anything like this and simply doesn't understand.
> >
> >It's not so difficult to open your mind to new experiences and new
> >ideas. But first one has to stop being a smartarse, and that I don't
> >think poor old Trevor can manage.
>
> You of course would be the master of this art - except that your arse
> is the smartest part of you.
>
> >> With 845, just no need for the 106dB of added NFB used in SS amps.
> >> I don't care a bit about what Trev says.
>
> With SS, no need for the massive cost of the output transformer for 50
> watts of single-ended tube amplification, plus of course you get much
> better linearity than even the mighty 845 can manage. A really good
> 60-watt SS amp is very easy to implement these days - and you can buy
> one for the cost of a pair of those OPTs...............
>
> --
>
> Stewart Pinkerton | Music is Art - Audio is Engineering
>
> Posted Via Usenet.com Premium Usenet Newsgroup Services
> ----------------------------------------------------------
> ** SPEED ** RETENTION ** COMPLETION ** ANONYMITY **
> ----------------------------------------------------------
> http://www.usenet.com

[Trevor Wilson]

"Patrick Turner" > wrote in message
...
>
>
> Andre Jute wrote:
>
>> I must say, Wilson, I don't understand why you're getting your knickers
>> in a knot. You're like those bolshies I used to know who claimed that
>> anyone who wasn't willing to kill for "socialism" was only play-acting.
>> Are you really claiming that someone who merely uses the NFB he finds
>> lurking in DHTs can't belong to the club until he repents and uses
>> excessive amounts of loop NFB? Are you really claiming that the use of
>> lots and lots of NFB is a prerequisite for good audio design? Are you
>> really claiming that because a little NFB is a good thing, an unlimited
>> amount must therefore be better, and an infinite amount best of all?
>> Seems a bit immoderate to me, old chap.
>
> You will find yourself arguing at a man who has a head full of solid
> concrete.

**Really? Then, I take it, you approve of Jute's lies? That makes you an
idiot.

> Trev will never see the whole picture, and has never designed or built any
> amp in
> the last 30 years.

**Wrong and irrelevant. I am discussing Jute's lies. That you approve of
Jute's lies says a great deal about you.

> I try not to bother arguing the same old tired BS time after time.
> He just likes hanging out in news groups and Bull****ting.
> He has NEVER once contributed a single article of constructive advice on
> tubecraft
> at r.a.t.

**And why should I? Tube technology matured in 1966. There was nothing much
to be added beyond that time.

>
>>
>>
>> Your hysterical belief that I am "against" NFB is the product of your
>> unsophisticated literal-mindedness. There is no reason for NFB to be an
>> act of faith, like an on-off switch. For the record, quite contrary to
>> your silly claims about what I said, I believe the little NFB that
>> occurs naturally in triodes and in certain conservatively sanctioned
>> traditional topologies are A Good Thing. To avoid giving you another
>> apoplectic fit, I shan't repeat what I think of the excessive amounts
>> of NFB required to make transistors work at all.
>>
>> If you think you can write a more compelling argument than I can about
>> the evils of excessive NFB, have at it. But every time I see you, like
>> the other techies you merely kibbitz what better men have written.
>
> I am now doing 845 amps, two per channel for 50 watts each.
> I expect music to be real fine. Damping factor good, noise low,
> bandwidth wide, distortions negligible and maybe I can add 6db of global
> NFB but
> I doubt any difference due to some **added** NFB will be heard.
>
> Trev has never done anything like this and simply doesn't understand.

**Anything like what? Be precise and relate it to my comments on Jute's
lies.

>
> With 845, just no need for the 106dB of added NFB used in SS amps.
> I don't care a bit about what Trev says.

**What do I say (WRT Jute's lies)? Be precise and relate his lies to your
own culpability in those lies.


--
Trevor Wilson
www.rageaudio.com.au

[Arny Krueger]

"Patrick Turner" > wrote in message

> All I hear from Oinkerton is "Oink....oink oink
> oink......squeal, oink...."
>
> I doubt he makes any thing.
>
> Patrick Turner.


Yet another prerequisite subjectivist personal attack.

[Nick Gorham]

Patrick Turner wrote:

>
>
> A colleague in Sydney is doing an SE amp with 6 x GM70 for 120 watts.
> But it will be switchable to PP......its doable, 5 very good switches are needed, and I
> did the OPT design.
>
> Whether the GM70 is better than 845 is unknown.
>

IMHO, we found that the graphite GM70 is not as good as the copper GM70,
the copper GM70 was nicer than cheap Chinese 845's, but I don't know how
the newer metal plate 845 or NOS 845 would sit in that list.

Though, what do I know, I still prefer the 211 :-).

I would have thought that 4 graphite GM70's would be enough for 120w.

BTW, HF heating makes the GM70 a lot simpiler to use.

--
Nick

[Andy Evans]

the copper GM70 was nicer than cheap Chinese 845's>

Any experiences of how these work as low power PP amps, as 845 has done
for many users? I was thinking about 450v HT. Andy

[Bret Ludwig]

Andy Evans wrote:
> the copper GM70 was nicer than cheap Chinese 845's>
>
> Any experiences of how these work as low power PP amps, as 845 has done
> for many users? I was thinking about 450v HT. Andy

At 450 V the 845 is a pretty crappy tube. At its rated B+ it's a
wonderful tube except it takes too much drive.

To get back to the subject of negative feedback, I firmly believe it's
very tough to make a worthwhile amp without modest amounts of NFB, but
that one should try to make the circuit as linear as possible before
applying NFB and use it in moderate amounts. Amplifiers with no NFB
(except for what is locally inherent in the devices, particularly
triode tubes) usually sound queefy and those with very high global NFB
usually sound hostile.

[Andre Jute]

Trevor Wilson wrote:
> Here are a few of your lies (some of which you have backtracked on):

And then this nutter Wilson lists:

-- a set of incontrovertible facts agreed by all parties, without
explaining how the facts straight out of the RDH can be a lie

-- a set of my opinions on matters of taste, without explaining how a
cultural taste can be a lie

-- and so on into astounding subdivisions of irrationality and
stupidity

Let's take just one example of what Wilson declares a lie. I wrote:

> "Let me say that again: after NFB, third and higher harmonics will make up a
> greater part of the distortion than before."

According to Wilson that is "a lie". Really? It is in fact a fact
(heh-heh) agreed between all informed parties that the NFB, while
reducing the *total* amount of distortion, by its very nature alters
the frequency distribution of the remaining distortion so that the odd
and higher harmonics make up a greater proportion of the recombinant
residual. That is several times spelt out in my original article which
causes Wilson to foam at the mouth. So tell us, Trevor-baby, how is my
statement lie?

I can't resist. Here's another statement (a rhetorical question,
actually) this blockhead Wilson singles out as "a lie":

> "And they still use Negative Feedback?"

Uh, duh, Trevor-baby, are you now claiming that the entire audio world
has stopped using NFB? Amazing.

Below my signature I reprint Wilson's entire hysterical (and
hysterically funny) letter in full for connoisseurs of audio
fruitcakery.

What a blockhead.

Andre Jute

> "Andre Jute" > wrote in message
> oups.com...
> > Trevor Wilson wrote:
> >>Incorrect and innappropriate application
> >> of NFB can damage an amplifier's performance.
> >
> > Now you're getting it, sonny.
>
> **Then say so. Stop telling half-truths. There is NOTHING wrong with NFB, as
> long as it is appropriately applied.
>
> > Next, try not to describe as a liar
> > anyone who doesn't instantly subscribe to your fanatical faith in Blow
> > Jobs from Transvestites (BJTs) and soon the rest of us might take you
> > seriously.
>
> **I only tell it like it is.
>
> Here are a few of your lies (some of which you have backtracked on):
>
> "Negative feedback, shorthanded as NFB, is the instant response of the audio
> engineering fraternity to all ills, real, perceived, non-existent."
>
> "How does negative feedback work?
> Negative feedback is simply a negative voltage fed back from the output to
> the input amplifying device to offset part of the harmonic distortion which
> is present as a positive voltage. It costs nothing except a loss of gain and
> a few side effects such as phase shift and possible instability which are
> well known in the mathematical literature and more or less easily guarded
> against depending on the level of NFB."
>
> "Negative feedback is what gives all those 'blameless' transistor and big
> PP tube amps their chillingly unnatural sound."
>
> "(I know, because a sub-board I designed for a supplier to the trade turns
> up in so many very expensive amps with so many different big names neatly
> silkscreened on it..."
>
> " Suppose, for the sake of simplicity, a superbly designed ultrafidelista
> amp with some second harmonic and zero odd harmonics before NFB."
>
> "Let me say that again: after NFB, third and higher harmonics will make up a
> greater part of the distortion than before."
>
> "Low volume levels perforce accounts for 99 per cent of audiophile listening
> because we all have families or neighbours, and we would like to keep our
> ears."
>
> "And they still use Negative Feedback?"
>
> "The case against NFB is that for 99 per cent of listening the NFB cure is
> worse than the disease."
>
> "It follows from the argument above that ultrafidelista should choose an
> intrinsically linear topology and device which does not require added
> negative feedback to 'linearize' the output."
>
> "The intrinsically linear device is the thermionic tube in either its triode
> form or as a pentode hogtied to work as a triode, which can be a most
> pleasing alternative both economically and sonically."
>
> "In comparative ABX tests conducted over a number of years, I found that
> professional musicians, certified golden ears, choose the triode-linked
> Class A1 PP ZNFB EL34 whenever it is present in the test over all other
> contenders including SE 300B and 'blameless' high-NFB silicon."
>
> "But transistor amps won't work at all without NFB!"
>
> "Engineering hangers-on of transistor attempts at high fidelity, where the
> measure of success is vanishing THD rather than sonic hedonism, pretend to
> be enthusiasts for NFB."
>
> "They sneer that low level listening, which 99 per cent of us prefer"
>
> "According to them we should all be forced to listen at the high volume
> level which suits NFB amps, which they call 'realistic'."
>
> "This is a contemptible circular argument, only too characteristic of a
> fascist mentality in a part of the audiophile spectrum which wants to
> prescribe their arid vision without regard for our enjoyment."
>
> "Almost everyone listens at low level most of the time."
>
> "Negative feedback is a bodge."
>
>
> Would you care to amend these lies and state PRECISELY what you mean?
>
>
> --
> Trevor Wilson
> www.rageaudio.com.au

[Patrick Turner]

Trevor Wilson wrote:

> "Patrick Turner" > wrote in message
> ...
> >
> >
> > Andre Jute wrote:
> >
> >> I must say, Wilson, I don't understand why you're getting your knickers
> >> in a knot. You're like those bolshies I used to know who claimed that
> >> anyone who wasn't willing to kill for "socialism" was only play-acting.
> >> Are you really claiming that someone who merely uses the NFB he finds
> >> lurking in DHTs can't belong to the club until he repents and uses
> >> excessive amounts of loop NFB? Are you really claiming that the use of
> >> lots and lots of NFB is a prerequisite for good audio design? Are you
> >> really claiming that because a little NFB is a good thing, an unlimited
> >> amount must therefore be better, and an infinite amount best of all?
> >> Seems a bit immoderate to me, old chap.
> >
> > You will find yourself arguing at a man who has a head full of solid
> > concrete.
>
> **Really? Then, I take it, you approve of Jute's lies? That makes you an
> idiot.

First of all, Jute's Lies as you call them are merely his opinion.

Its a free world and I tolerate opinions; I do not necessarily agree with them,
and
it is my opinion that your head is so chock full of concrete that you draw the
absurd conconclusion
that I am a fool because you have erroneously assumed I agree with all of Jute's
ideas without question.

I have heard Jute on all this several times before, and would be wasting time to
flame him about his opinions.

Jute uses and tolerates quite a number of different amplifiers which include SET
without added loops of NFB.
Jute is pro tube craft.

Now Trev, do us all a favour and just **** off out of rec.audio.tubes because
you come here with a hammer.
On your way out, leave your tube breaking hammer in the re-cycle bin.

Come back when you have something constructive to say about tube craft,
and can share our craft in a practical way ( build a tube amp, ok ) and share
the experience in a tolerant spirit.

Patrick Turner.

>
>
> > Trev will never see the whole picture, and has never designed or built any
> > amp in
> > the last 30 years.
>
> **Wrong and irrelevant. I am discussing Jute's lies. That you approve of
> Jute's lies says a great deal about you.
>
> > I try not to bother arguing the same old tired BS time after time.
> > He just likes hanging out in news groups and Bull****ting.
> > He has NEVER once contributed a single article of constructive advice on
> > tubecraft
> > at r.a.t.
>
> **And why should I? Tube technology matured in 1966. There was nothing much
> to be added beyond that time.
>
> >
> >>
> >>
> >> Your hysterical belief that I am "against" NFB is the product of your
> >> unsophisticated literal-mindedness. There is no reason for NFB to be an
> >> act of faith, like an on-off switch. For the record, quite contrary to
> >> your silly claims about what I said, I believe the little NFB that
> >> occurs naturally in triodes and in certain conservatively sanctioned
> >> traditional topologies are A Good Thing. To avoid giving you another
> >> apoplectic fit, I shan't repeat what I think of the excessive amounts
> >> of NFB required to make transistors work at all.
> >>
> >> If you think you can write a more compelling argument than I can about
> >> the evils of excessive NFB, have at it. But every time I see you, like
> >> the other techies you merely kibbitz what better men have written.
> >
> > I am now doing 845 amps, two per channel for 50 watts each.
> > I expect music to be real fine. Damping factor good, noise low,
> > bandwidth wide, distortions negligible and maybe I can add 6db of global
> > NFB but
> > I doubt any difference due to some **added** NFB will be heard.
> >
> > Trev has never done anything like this and simply doesn't understand.
>
> **Anything like what? Be precise and relate it to my comments on Jute's
> lies.
>
> >
> > With 845, just no need for the 106dB of added NFB used in SS amps.
> > I don't care a bit about what Trev says.
>
> **What do I say (WRT Jute's lies)? Be precise and relate his lies to your
> own culpability in those lies.
>
> --
> Trevor Wilson
> www.rageaudio.com.au

[Trevor Wilson]

"Andre Jute" > wrote in message
oups.com...
> Trevor Wilson wrote:
>> Here are a few of your lies (some of which you have backtracked on):
>
> And then this nutter Wilson lists:

**A whole big bunch of your lies. Nothing more.

>
> -- a set of incontrovertible facts agreed by all parties, without
> explaining how the facts straight out of the RDH can be a lie

**Cite your alleged "incontrovertible facts". I'll wait. I have copy of
RDH4. Just give me the page and chapter reference numbers.

>
> -- a set of my opinions on matters of taste, without explaining how a
> cultural taste can be a lie

**I have not argued with your opinions. Just your lies.

>
> -- and so on into astounding subdivisions of irrationality and
> stupidity

**Really? How about discussing your lies then? Let's see if you can manage
it, without profanity and insults. Just calmly and rationally discuss my
points, one by one. I bet you can't.

>
> Let's take just one example of what Wilson declares a lie.

**No, let's discuss the entirety of my post.

I wrote:
>
>> "Let me say that again: after NFB, third and higher harmonics will make
>> up a
>> greater part of the distortion than before."
>
> According to Wilson that is "a lie". Really?

**An half truth. You leave out the obvious fact that IF odd order distortion
is reduced to inaudibility (which it is in all competently designed amps),
then it is irrelevant what part of the distortion is even or odd. I said I
was addressing your lies and half truths.

It is in fact a fact
> (heh-heh) agreed between all informed parties that the NFB, while
> reducing the *total* amount of distortion, by its very nature alters
> the frequency distribution of the remaining distortion so that the odd
> and higher harmonics make up a greater proportion of the recombinant
> residual. That is several times spelt out in my original article which
> causes Wilson to foam at the mouth. So tell us, Trevor-baby, how is my
> statement lie?

**It is a half truth.

>
> I can't resist. Here's another statement (a rhetorical question,
> actually) this blockhead Wilson singles out as "a lie":
>
>> "And they still use Negative Feedback?"
>
> Uh, duh, Trevor-baby, are you now claiming that the entire audio world
> has stopped using NFB? Amazing.

**Nope. It is a half truth. EVERYONE uses NFB. Every single amplifier
designer. Even you. By not spelling what type of NFB you are telling half
truths.

>
> Below my signature I reprint Wilson's entire hysterical (and
> hysterically funny) letter in full for connoisseurs of audio
> fruitcakery.
>
> What a blockhead.

**I note that you still cannot answer my questions. Not bad for a
"blockhead" huh? If you are so smart, then prove it, by demonstrating that
each and every one of my points is incorrect.

I'll wait.


--
Trevor Wilson
www.rageaudio.com.au

[Andre Jute]

Wilson, you're quite mad. If I wrote according to your demands, every
sentence would be two thousand words long and require 200 footnotes
(another 10K words between them!) to cover all eventualities, and then
you would pick nits out of what is left of your hair about the order of
the footnotes.

Since you're so convinced NFB is the Second Coming, you're welcome to
write a full commentary on my piece and send it to me to publish on my
netsite. We can do with a comedy section. You should be aware though
that a couple of appearances in the comedy section of my netsite (once
for his ignorance on power supplies (1), once for the same matter of
distortion distribution that so upsets you (2)) cost Mike LeFevre
two-thirds of his existing business and closed out several avenues to
fame and riches just then opening up to him. Several years later he
still hasn't recovered. I'm sure you've wept for him...

I don't imagine that, dragging around an attitude like yours, you do
much business, but still, if it is your living perhaps you should not
sign your business-name to these tirades that do nothing more than make
you look ineffably stupid and offensive.

Andre Jute

(1) Google for "DC on the core"
(2) Google for the "Bubbaland 300B"

Trevor Wilson wrote:
> "Andre Jute" > wrote in message
> oups.com...
> > Trevor Wilson wrote:
> >> Here are a few of your lies (some of which you have backtracked on):
> >
> > And then this nutter Wilson lists:
>
> **A whole big bunch of your lies. Nothing more.
>
> >
> > -- a set of incontrovertible facts agreed by all parties, without
> > explaining how the facts straight out of the RDH can be a lie
>
> **Cite your alleged "incontrovertible facts". I'll wait. I have copy of
> RDH4. Just give me the page and chapter reference numbers.
>
> >
> > -- a set of my opinions on matters of taste, without explaining how a
> > cultural taste can be a lie
>
> **I have not argued with your opinions. Just your lies.
>
> >
> > -- and so on into astounding subdivisions of irrationality and
> > stupidity
>
> **Really? How about discussing your lies then? Let's see if you can manage
> it, without profanity and insults. Just calmly and rationally discuss my
> points, one by one. I bet you can't.
>
> >
> > Let's take just one example of what Wilson declares a lie.
>
> **No, let's discuss the entirety of my post.
>
> I wrote:
> >
> >> "Let me say that again: after NFB, third and higher harmonics will make
> >> up a
> >> greater part of the distortion than before."
> >
> > According to Wilson that is "a lie". Really?
>
> **An half truth. You leave out the obvious fact that IF odd order distortion
> is reduced to inaudibility (which it is in all competently designed amps),
> then it is irrelevant what part of the distortion is even or odd. I said I
> was addressing your lies and half truths.
>
> It is in fact a fact
> > (heh-heh) agreed between all informed parties that the NFB, while
> > reducing the *total* amount of distortion, by its very nature alters
> > the frequency distribution of the remaining distortion so that the odd
> > and higher harmonics make up a greater proportion of the recombinant
> > residual. That is several times spelt out in my original article which
> > causes Wilson to foam at the mouth. So tell us, Trevor-baby, how is my
> > statement lie?
>
> **It is a half truth.
>
> >
> > I can't resist. Here's another statement (a rhetorical question,
> > actually) this blockhead Wilson singles out as "a lie":
> >
> >> "And they still use Negative Feedback?"
> >
> > Uh, duh, Trevor-baby, are you now claiming that the entire audio world
> > has stopped using NFB? Amazing.
>
> **Nope. It is a half truth. EVERYONE uses NFB. Every single amplifier
> designer. Even you. By not spelling what type of NFB you are telling half
> truths.
>
> >
> > Below my signature I reprint Wilson's entire hysterical (and
> > hysterically funny) letter in full for connoisseurs of audio
> > fruitcakery.
> >
> > What a blockhead.
>
> **I note that you still cannot answer my questions. Not bad for a
> "blockhead" huh? If you are so smart, then prove it, by demonstrating that
> each and every one of my points is incorrect.
>
> I'll wait.
>
>
> --
> Trevor Wilson
> www.rageaudio.com.au

[Andre Jute]

Hey, Trev-baby, you're doing a really good job with all this
mouth-foaming of persuading people to give me a hearing. After all, if
you and the "engineers" Pinkerton, Krueger, Pearce, and so on, are the
best that the opposition can bring, i win the argument by default. This
is easier than taking candy from a baby.

Thanks, pal.

Andre Jute
I dunno why I went to night skool to lurn to be a hard case when the
bad guys are so soft

Trevor Wilson wrote:
> "Patrick Turner" > wrote in message
> ...
> >
> >
> > Trevor Wilson wrote:
> >
> >> "Patrick Turner" > wrote in message
> >> ...
> >> >
> >> >
> >> > Andre Jute wrote:
> >> >
> >> >> I must say, Wilson, I don't understand why you're getting your
> >> >> knickers
> >> >> in a knot. You're like those bolshies I used to know who claimed that
> >> >> anyone who wasn't willing to kill for "socialism" was only
> >> >> play-acting.
> >> >> Are you really claiming that someone who merely uses the NFB he finds
> >> >> lurking in DHTs can't belong to the club until he repents and uses
> >> >> excessive amounts of loop NFB? Are you really claiming that the use of
> >> >> lots and lots of NFB is a prerequisite for good audio design? Are you
> >> >> really claiming that because a little NFB is a good thing, an
> >> >> unlimited
> >> >> amount must therefore be better, and an infinite amount best of all?
> >> >> Seems a bit immoderate to me, old chap.
> >> >
> >> > You will find yourself arguing at a man who has a head full of solid
> >> > concrete.
> >>
> >> **Really? Then, I take it, you approve of Jute's lies? That makes you an
> >> idiot.
> >
> > First of all, Jute's Lies as you call them are merely his opinion.
>
> **Jute does not state them as opinions. He puts them forward as fact. Do you
> fully and completely support his "facts"? Or do you dispute some (much) of
> what he writes and you just hate me more than you hate him?
>
> >
> > Its a free world and I tolerate opinions;
>
> **As do I. Opinions are fine. I rarely argue with them. I will argue with
> lies and half truths, however.
>
> I do not necessarily agree with them,
> > and
> > it is my opinion that your head is so chock full of concrete that you draw
> > the
> > absurd conconclusion
> > that I am a fool because you have erroneously assumed I agree with all of
> > Jute's
> > ideas without question.
>
> **If you dissagree with Jute's FACTS, then say so.
>
> >
> > I have heard Jute on all this several times before, and would be wasting
> > time to
> > flame him about his opinions.
>
> **Jute is not stating opinions. He is claiming that he states facts. Just
> read what he wrote. There are no opinions stated anywhere.
>
> >
> > Jute uses and tolerates quite a number of different amplifiers which
> > include SET
> > without added loops of NFB.
> > Jute is pro tube craft.
>
> **Irrelevant. Jute is claiming a whole bunch of utter nonsense.
>
> >
> > Now Trev, do us all a favour and just **** off out of rec.audio.tubes
> > because
> > you come here with a hammer.
>
> **You go and get yourself well and truely ****ed. I will enter any newsgroup
> I wish, whenever I wish. Jute crossposted his missive all over the internet.
> If you have a problem with that, take it up with Jute, not me. HE is your
> problem, not me.
>
> > On your way out, leave your tube breaking hammer in the re-cycle bin.
>
> **As above.
>
> >
> > Come back when you have something constructive to say about tube craft,
> > and can share our craft in a practical way ( build a tube amp, ok ) and
> > share
> > the experience in a tolerant spirit.
>
> **I have done so, many times. I've built tube preamps, power amps, tuners,
> pre-pre amps and a whole bunch of other stuff. It's no longer interesting,
> as the technology is dead. Solid state offers far more potential. As I
> carefully explained to Jute, modern transistors are more linear than his
> favoured triodes. The battle is finished. They keep their peak performance
> forever and don't need those pesky output transformers to interface with
> loudspeakers. And, a note to Jute: They don't need Global NFB to keep them
> linear either. Just because most of the mass market builders do use it, does
> not mean everyone does.
>
>
> --
> Trevor Wilson
> www.rageaudio.com.au

[Stewart Pinkerton]

On Sat, 25 Mar 2006 18:58:47 GMT, Patrick Turner
> wrote:


>All I hear from Oinkerton is "Oink....oink oink oink......squeal, oink...."
>
>I doubt he makes any thing.

I doubt you make anything that sounds like its input signal.

Failure to address the technical points noted.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

[Stewart Pinkerton]

On 26 Mar 2006 02:21:53 -0800, "Andre Jute" > wrote:

>Hey, Trev-baby, you're doing a really good job with all this
>mouth-foaming of persuading people to give me a hearing. After all, if
>you and the "engineers" Pinkerton, Krueger, Pearce, and so on, are the
>best that the opposition can bring, i win the argument by default. This
>is easier than taking candy from a baby.

Of course, the reality is that you're so technically incompetent that
you don't even understand when your position has been obliterated.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
** SPEED ** RETENTION ** COMPLETION ** ANONYMITY **
----------------------------------------------------------
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[Trevor Wilson]

"Patrick Turner" > wrote in message
...
>
> Snip a pile of **** that Trevor wrote without reading it......
>
> I said.......................
>
>>
>> > On your way out, leave your tube breaking hammer in the re-cycle bin.
>>
>> **As above.
>>
>> >
>> > Come back when you have something constructive to say about tube craft,
>> > and can share our craft in a practical way ( build a tube amp, ok ) and
>> > share
>> > the experience in a tolerant spirit.
>>
>> **I have done so, many times. I've built tube preamps, power amps,
>> tuners,
>> pre-pre amps and a whole bunch of other stuff. It's no longer
>> interesting,
>> as the technology is dead. Solid state offers far more potential. As I
>> carefully explained to Jute, modern transistors are more linear than his
>> favoured triodes. The battle is finished. They keep their peak
>> performance
>> forever and don't need those pesky output transformers to interface with
>> loudspeakers. And, a note to Jute: They don't need Global NFB to keep
>> them
>> linear either. Just because most of the mass market builders do use it,
>> does
>> not mean everyone does.
>
> But you have not designed or built ANYTHING for 30 years ever since you
> met
> Peter Stein
> who designed the ME technology range of Oz amps.
>
> On numerous occasions both Phil Allison and myself have had to correct
> your
> gross ignorance with techical details
> of amplifiers.
>
> Your record is that you are a buffoon grandiose.
>
> Your miserable paragraph above contains reams of technical errors not
> worth
> responding to.
>
> Just **** off, you are a dead boring old man with nothing in you that
> anyone
> else wants to share.
>
> Keep contributing to rec.audio.tubes, and all you will ever achieve is
> bigger BS
> artist status.

**You have, as usual, COMPLETELY missed the point. Let me see if I can
explain it to you in terms which a 9 year old can understand:

I was responding to Jute's lies and half truths. Nothing more. I am not
bashing tubes and those who have a preference for tube amplifiers. That is
their choice and they are entitled to it. I was merely responding to Jute's
lies and half truths. Since you are attacking me and not Jute, I can only
assume that you share Jute's incorrect view of things.


--
Trevor Wilson
www.rageaudio.com.au

[Trevor Wilson]

"Andre Jute" > wrote in message
ups.com...
> Wilson, you're quite mad. If I wrote according to your demands, every
> sentence would be two thousand words long and require 200 footnotes
> (another 10K words between them!) to cover all eventualities, and then
> you would pick nits out of what is left of your hair about the order of
> the footnotes.

**Then do so. I'll wait. We both know you can't. In fact, I'll make it easy
for you: Let's just discuss one, lone lie. YOU justify your lie about a
triode being more linear than a MODERN BJT. Not a 30 year old one, but an
up-to-date device.

>
> Since you're so convinced NFB is the Second Coming,

**Nothing of the sort. NFB is unavoidable, that's all. NFB is used in EVERY
SINGLE amplifier on the planet. It's just the type and amount of NFB which
varies. A point you manage to neatly avoid in everything you write. You
additionally manage to avoid the fact that transistor amps can be built
which do not use Global NFB, if required.

you're welcome to
> write a full commentary on my piece and send it to me to publish on my
> netsite.

**You already have my criticism of what you wrote.

We can do with a comedy section. You should be aware though
> that a couple of appearances in the comedy section of my netsite (once
> for his ignorance on power supplies (1), once for the same matter of
> distortion distribution that so upsets you (2)) cost Mike LeFevre
> two-thirds of his existing business and closed out several avenues to
> fame and riches just then opening up to him. Several years later he
> still hasn't recovered. I'm sure you've wept for him...
>
> I don't imagine that, dragging around an attitude like yours, you do
> much business, but still, if it is your living perhaps you should not
> sign your business-name to these tirades that do nothing more than make
> you look ineffably stupid and offensive.

**As opposed to your complete inability to answer my questions and points?
Yeah, sure.


--
Trevor Wilson
www.rageaudio.com.au

[Bret Ludwig]

>
> We can do with a comedy section. You should be aware though
> > that a couple of appearances in the comedy section of my netsite (once
> > for his ignorance on power supplies (1), once for the same matter of
> > distortion distribution that so upsets you (2)) cost Mike LeFevre
> > two-thirds of his existing business and closed out several avenues to
> > fame and riches just then opening up to him. Several years later he
> > still hasn't recovered. I'm sure you've wept for him...
>

Andre Jute is not responsible for Mike Lefevre's woes. Mike Lefevre
is. People got tired of his rank dishonesty and ineptitude. Andre got
on the bandwagon when it became apparent he was going down. Not that
Lefevre deserves any sympathy.

[Andre Jute]

Wilson, you're getting nuttier and nuttier. First you claim my opinions
and some really basic, totally uncontroversial science are lies because
I haven't dotted thousands of tees you claim make your contrary point.
Now you want me to defend tubes against BJTs, which as far as I can
tell are Blow Jobs by Transvestites. I'm not queer, I see no need to
defend tubes against every passing hanger-on of the silicon slime (to
me you and MIckey McMickey sound equally uninformed and equally
deranged), and I see absolutely no reason to defend either my opinions
or my facts against some salesman with commercially inspired contrary
opinions. If you want to come with chapter and verse about negative
feedback, with all sources fully cited and a logically reasoned
development, by all means do so; we will then pay you the respect of
serious discussion but you should be aware that we are unlikely to
change our taste at the bidding of anyone as singularly lacking in
charm as you. Until you do bring facts and reasoning and persuasion
rather than your present bullying thuggery, your kibbitzing is just
your opinion--and it isn't worth even a fraction of my opinion. You're
in my killfile as a waste of time until I see others discussing some
serious point you made, if ever you manage to make one.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

Trevor Wilson wrote:
> "Andre Jute" > wrote in message
> ups.com...
> > Wilson, you're quite mad. If I wrote according to your demands, every
> > sentence would be two thousand words long and require 200 footnotes
> > (another 10K words between them!) to cover all eventualities, and then
> > you would pick nits out of what is left of your hair about the order of
> > the footnotes.
>
> **Then do so. I'll wait. We both know you can't. In fact, I'll make it easy
> for you: Let's just discuss one, lone lie. YOU justify your lie about a
> triode being more linear than a MODERN BJT. Not a 30 year old one, but an
> up-to-date device.
>
> >
> > Since you're so convinced NFB is the Second Coming,
>
> **Nothing of the sort. NFB is unavoidable, that's all. NFB is used in EVERY
> SINGLE amplifier on the planet. It's just the type and amount of NFB which
> varies. A point you manage to neatly avoid in everything you write. You
> additionally manage to avoid the fact that transistor amps can be built
> which do not use Global NFB, if required.
>
> you're welcome to
> > write a full commentary on my piece and send it to me to publish on my
> > netsite.
>
> **You already have my criticism of what you wrote.
>
> We can do with a comedy section. You should be aware though
> > that a couple of appearances in the comedy section of my netsite (once
> > for his ignorance on power supplies (1), once for the same matter of
> > distortion distribution that so upsets you (2)) cost Mike LeFevre
> > two-thirds of his existing business and closed out several avenues to
> > fame and riches just then opening up to him. Several years later he
> > still hasn't recovered. I'm sure you've wept for him...
> >
> > I don't imagine that, dragging around an attitude like yours, you do
> > much business, but still, if it is your living perhaps you should not
> > sign your business-name to these tirades that do nothing more than make
> > you look ineffably stupid and offensive.
>
> **As opposed to your complete inability to answer my questions and points?
> Yeah, sure.
>
>
> --
> Trevor Wilson
> www.rageaudio.com.au

[Trevor Wilson]

"Andre Jute" > wrote in message
ups.com...
> Wilson, you're getting nuttier and nuttier. First you claim my opinions
> and some really basic, totally uncontroversial science are lies because
> I haven't dotted thousands of tees you claim make your contrary point.

**Nope. I claim that in your original post, you lied. Many times. You are as
entitled to your OPINIONS as much as anyone else. When you lie, however, I
(and others) will take you to task.

> Now you want me to defend tubes against BJTs, which as far as I can
> tell are Blow Jobs by Transvestites.

**Nope. YOU claimed that triodes were the most linear amplification device.
Up until the development of modern transistors, that may have been the case.
It has not been the case for many years, however.

I'm not queer, I see no need to
> defend tubes against every passing hanger-on of the silicon slime (to
> me you and MIckey McMickey sound equally uninformed and equally
> deranged), and I see absolutely no reason to defend either my opinions
> or my facts against some salesman with commercially inspired contrary
> opinions.

**You don't have to defend your opinions. When you state alleged facts,
however, you will be called to task.

If you want to come with chapter and verse about negative
> feedback, with all sources fully cited and a logically reasoned
> development,

**What do you want to know? You seem to be unable to distinguish between
Global NFB, local NFB, nested NFB and any other sort. Is that correct? Or do
you actually KNOW that there are basic and fundamental differences between
the different NFB schemes and you choose not to explain that to your
readers?

by all means do so; we will then pay you the respect of
> serious discussion but you should be aware that we are unlikely to
> change our taste at the bidding of anyone as singularly lacking in
> charm as you.

**Charm is for getting laid. We are discussing facts (or lack of, in your
case). If you were an attractive woman and I did not live with a homicidal
female, I would be charming to you.

Until you do bring facts and reasoning and persuasion
> rather than your present bullying thuggery, your kibbitzing is just
> your opinion

**Then feel free to discuss my "opinions" and rebutt them with facts. I'll
wait.


--and it isn't worth even a fraction of my opinion. You're
> in my killfile as a waste of time until I see others discussing some
> serious point you made, if ever you manage to make one.

**Typical wimp.

>
> Trevor Wilson wrote:
>> "Andre Jute" > wrote in message
>> ups.com...
>> > Wilson, you're quite mad. If I wrote according to your demands, every
>> > sentence would be two thousand words long and require 200 footnotes
>> > (another 10K words between them!) to cover all eventualities, and then
>> > you would pick nits out of what is left of your hair about the order of
>> > the footnotes.
>>
>> **Then do so. I'll wait. We both know you can't. In fact, I'll make it
>> easy
>> for you: Let's just discuss one, lone lie. YOU justify your lie about a
>> triode being more linear than a MODERN BJT. Not a 30 year old one, but an
>> up-to-date device.
>>
>> >
>> > Since you're so convinced NFB is the Second Coming,
>>
>> **Nothing of the sort. NFB is unavoidable, that's all. NFB is used in
>> EVERY
>> SINGLE amplifier on the planet. It's just the type and amount of NFB
>> which
>> varies. A point you manage to neatly avoid in everything you write. You
>> additionally manage to avoid the fact that transistor amps can be built
>> which do not use Global NFB, if required.
>>
>> you're welcome to
>> > write a full commentary on my piece and send it to me to publish on my
>> > netsite.
>>
>> **You already have my criticism of what you wrote.
>>
>> We can do with a comedy section. You should be aware though
>> > that a couple of appearances in the comedy section of my netsite (once
>> > for his ignorance on power supplies (1), once for the same matter of
>> > distortion distribution that so upsets you (2)) cost Mike LeFevre
>> > two-thirds of his existing business and closed out several avenues to
>> > fame and riches just then opening up to him. Several years later he
>> > still hasn't recovered. I'm sure you've wept for him...
>> >
>> > I don't imagine that, dragging around an attitude like yours, you do
>> > much business, but still, if it is your living perhaps you should not
>> > sign your business-name to these tirades that do nothing more than make
>> > you look ineffably stupid and offensive.
>>
>> **As opposed to your complete inability to answer my questions and
>> points?
>> Yeah, sure.
>>
>>
>> --
>> Trevor Wilson
>> www.rageaudio.com.au
>


--
Trevor Wilson
www.rageaudio.com.au

[Stewart Pinkerton]

On 26 Mar 2006 17:16:29 -0800, "Andre Jute" > wrote:

>Wilson, you're getting nuttier and nuttier. First you claim my opinions
>and some really basic, totally uncontroversial science are lies because
>I haven't dotted thousands of tees you claim make your contrary point.
>Now you want me to defend tubes against BJTs, which as far as I can
>tell are Blow Jobs by Transvestites.

I notice you fail to address the fact that the modern BJT can be more
linear *without feedback* than your beloved DHTs. Surely a *true*
'ultrafidelista' would see this as the Holy Grail of the 'silent'
amplifier? Better linearity and no humming heaters?

>I'm not queer, I see no need to
>defend tubes against every passing hanger-on of the silicon slime (to
>me you and MIckey McMickey sound equally uninformed and equally
>deranged),

Typical of your ignorance to be unaware that there is *vastly* more
silicon in a tube amp than a BJT one.

> and I see absolutely no reason to defend either my opinions
>or my facts against some salesman with commercially inspired contrary
>opinions.

Interesting, since the only real job you ever had was as a salesman.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
** SPEED ** RETENTION ** COMPLETION ** ANONYMITY **
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[Patrick Turner]

Andre remarked that ..........................

> > Now you want me to defend tubes against BJTs, which as far as I can
> > tell are Blow Jobs by Transvestites.

A truly DIMWITTED Trevor Wilson replied.....

>
> **Nope. YOU claimed that triodes were the most linear amplification device.
> Up until the development of modern transistors, that may have been the case.
> It has not been the case for many years, however.

Unfortunately, Trevor has been spewing this drivel about BJTs being more linear
than triodes for years.

They are only as linear as a triode with regard to voltage gain when external
loops of NFB have been applied,
as in the case of the emitter follower connection or having a few BJTs with a
loop of NFB around the
lot of them to correct all their mistakes.

BJTs are inherently non linear for voltage gain and MUST rely on large amounts
of externally connected loops of NFB.

This applies regardless of whether you build a preamp with an opamp, a discrete
transistor preamp,
or any power amp.

Triodes don't, they have a small amount of NFB built into them.

I would ask Trevor to set up a simple 1 transistor preamp with a BC109, and
without any
NFB applied, not even an emitter current feedback resistor, and as a common
emitter voltage amplifier with a supply of 20V.

To understand his own utter stupidity, I ask Trevor to also set up a 6SN7 with a
250V supply to act as a preamp
and without any loop NFB, and he can then tell us all about the results which
will prove what a
jackarse he is.

I insist Trevor compare the results of either device with respect for both
devices and
with respect to us, himself and truthful analysis, but I do believe I am doing
the equivalant of asking a pig to fly.

Until proven otherwise, It can safely be assumed that all of Trevor's knowledge
will fit upon a pinhead.

The only reason TW hangs out here is so he can display how seriously limited he
is.

I delete the rest of TW's bull****e without reading it.

Patrick Turner.

[Patrick Turner]

Stewpid Oinkerton squealed....

> I notice you fail to address the fact that the modern BJT can be more
> linear *without feedback* than your beloved DHTs. Surely a *true*
> 'ultrafidelista' would see this as the Holy Grail of the 'silent'
> amplifier? Better linearity and no humming heaters?

The fact is that the modern transistor must rely on NFB for it to be
acceptable in any way.
Every transistor amp must use a lot more NFB to be acceptable than the NFB
that is within
a tube such as a 6SN7.

You are entitled to your opinion, but I cannot agree.

I delete the rest of your silly post; you come here like the pork seller to
the synagogue to sell your pork,
and I ain't buying.

Does it ever occur that you entirely waste your time and ours by trying to
hang out around here?

Patrck Turner.

[Arny Krueger]

"Patrick Turner" > wrote in message



> They are only as linear as a triode with regard to
> voltage gain when external loops of NFB have been applied,
> as in the case of the emitter follower connection or
> having a few BJTs with a loop of NFB around the
> lot of them to correct all their mistakes.

> BJTs are inherently non linear for voltage gain and MUST
> rely on large amounts of externally connected loops of
> NFB.

Simply not true. Local feedback works well with BJTs.

> This applies regardless of whether you build a preamp
> with an opamp, a discrete transistor preamp,
> or any power amp.
>
> Triodes don't, they have a small amount of NFB built into
> them.

Compared to BJTs, triodes have massive amounts of local NFB built into them,
and they are often used with addtiional local and/or loop NFB.

> I would ask Trevor to set up a simple 1 transistor preamp
> with a BC109, and without any
> NFB applied, not even an emitter current feedback
> resistor, and as a common emitter voltage amplifier with
> a supply of 20V.

An apples-to-apples comparison would involve comparing circuits with gain
and impedances, both input and output, that are as typical and similar as
possible. However, this comparison is totally ludicrous, because nobody in
their right mind uses a stand-alone BC109 as a high grade audio amplifier
any more. They'll use some kind of an op amp, perhaps a NE 5532 or its
equivalent.

> To understand his own utter stupidity, I ask Trevor to
> also set up a 6SN7 with a 250V supply to act as a preamp
> and without any loop NFB, and he can then tell us all
> about the results which will prove what a
> jackarse he is.

Illogical comparison. Everybody knows that 6SN7s have a ton of internal
feedback, and that BJTs compare most closely to pentodes, not triodes.

[Iain Churches]

"Stewart Pinkerton" > wrote in message
...
> On 26 Mar 2006 17:16:29 -0800, "Andre Jute" > wrote:
>
>>Wilson, you're getting nuttier and nuttier. First you claim my opinions
>>and some really basic, totally uncontroversial science are lies because
>>I haven't dotted thousands of tees you claim make your contrary point.
>>Now you want me to defend tubes against BJTs, which as far as I can
>>tell are Blow Jobs by Transvestites.
>
> I notice you fail to address the fact that the modern BJT can be more
> linear *without feedback* than your beloved DHTs. Surely a *true*
> 'ultrafidelista' would see this as the Holy Grail of the 'silent'
> amplifier? Better linearity and no humming heaters?

Erm. Stewart. DHTs don't have "heaters" :-((

Iain

[Arny Krueger]

"Patrick Turner" > wrote in message

> Stewpid Oinkerton squealed....
>
>> I notice you fail to address the fact that the modern
>> BJT can be more linear *without feedback* than your
>> beloved DHTs. Surely a *true* 'ultrafidelista' would see
>> this as the Holy Grail of the 'silent' amplifier? Better
>> linearity and no humming heaters?
>
> The fact is that the modern transistor must rely on NFB
> for it to be acceptable in any way.

As do the vaccum-state devices that compare best to BJTs - pentodes.

Turner wants us to think that using BJTs with emitter resistors is a crime
of some kind.

[Arny Krueger]

"Iain Churches" > wrote in message

> "Stewart Pinkerton" >
> wrote in message
> ...
>> On 26 Mar 2006 17:16:29 -0800, "Andre Jute"
>> > wrote:
>>> Wilson, you're getting nuttier and nuttier. First you
>>> claim my opinions and some really basic, totally
>>> uncontroversial science are lies because I haven't
>>> dotted thousands of tees you claim make your contrary
>>> point. Now you want me to defend tubes against BJTs,
>>> which as far as I can tell are Blow Jobs by
>>> Transvestites.
>>
>> I notice you fail to address the fact that the modern
>> BJT can be more linear *without feedback* than your
>> beloved DHTs. Surely a *true* 'ultrafidelista' would see
>> this as the Holy Grail of the 'silent' amplifier? Better
>> linearity and no humming heaters?
>
> Erm. Stewart. DHTs don't have "heaters" :-((

Yup, according to Iain, and contrary to popular belief, DHT does not stand
for "Directly HEATED Triode".

[Stewart Pinkerton]

On Mon, 27 Mar 2006 13:51:17 GMT, Patrick Turner
> wrote:

>Andre remarked that ..........................
>
>> > Now you want me to defend tubes against BJTs, which as far as I can
>> > tell are Blow Jobs by Transvestites.
>
>A truly DIMWITTED Trevor Wilson replied.....

Actually, the dimwit is clearly *you*, Turner.

>> **Nope. YOU claimed that triodes were the most linear amplification device.
>> Up until the development of modern transistors, that may have been the case.
>> It has not been the case for many years, however.
>
>Unfortunately, Trevor has been spewing this drivel about BJTs being more linear
>than triodes for years.

It's not drivel, it's basic fact which you are ignoring, in typical
tubie fashion.

>They are only as linear as a triode with regard to voltage gain when external
>loops of NFB have been applied,
>as in the case of the emitter follower connection or having a few BJTs with a
>loop of NFB around the
>lot of them to correct all their mistakes.

Utter rubbish. Check out the spec sheet of the 2SA1216, particularly
when used in class A, and therefore with an elevated junction
temperature and a collector current of an amp or more. It is *way*
more linear than the 300B which is held in such reverence by you guys.

That's why I specified its NPN complement 2SC2922 for KISASS. The PNP
2SA1216 is marginally more linear, but most folks are happier with
positive rail voltages.

>BJTs are inherently non linear for voltage gain and MUST rely on large amounts
>of externally connected loops of NFB.

Utter rubbish, see above.

>This applies regardless of whether you build a preamp with an opamp, a discrete
>transistor preamp,
>or any power amp.

Utter rubbish, see above.

>Triodes don't, they have a small amount of NFB built into them.
>
>I would ask Trevor to set up a simple 1 transistor preamp with a BC109, and
>without any
>NFB applied, not even an emitter current feedback resistor, and as a common
>emitter voltage amplifier with a supply of 20V.

I would ask you to set up an EF86.

>To understand his own utter stupidity, I ask Trevor to also set up a 6SN7 with a
>250V supply to act as a preamp
>and without any loop NFB, and he can then tell us all about the results which
>will prove what a
>jackarse he is.

The jackass is the one who has to specify a highly linear tube and a
pretty non-linear transistor to make his point. Try a 300B and a
2SC2922, and see what happens. Or of course you could put up the 6SN7
against any linear (as opposed to switching) high-voltage FET in
pretty much the same circuit, which is perhaps a fairer comparison.

If you were to want an *honest* comparison, you'd allow 10-15dB of
local degeneration in the SS circuit, to equate to the internal
feedback of the triode, but that's probably asking too much of a
tubie, especially as the result would be an even more crushing defeat
for the tube.

>I insist Trevor compare the results of either device with respect for both
>devices and
>with respect to us, himself and truthful analysis, but I do believe I am doing
>the equivalant of asking a pig to fly.

The result would not be in doubt - but you won't like it!

>Until proven otherwise, It can safely be assumed that all of Trevor's knowledge
>will fit upon a pinhead.

In the same analogy, one must assume that yours will fit comfortably
upon the point.

>The only reason TW hangs out here is so he can display how seriously limited he
>is.
>
>I delete the rest of TW's bull****e without reading it.

Shame, you just *might* have learned something - but I doubt it.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

[Stewart Pinkerton]

On Mon, 27 Mar 2006 14:03:30 GMT, Patrick Turner
> wrote:

>Stewpid Oinkerton squealed....

Typical of tubies to use childish namecalling in lieu of any
substantive argument.

>> I notice you fail to address the fact that the modern BJT can be more
>> linear *without feedback* than your beloved DHTs. Surely a *true*
>> 'ultrafidelista' would see this as the Holy Grail of the 'silent'
>> amplifier? Better linearity and no humming heaters?
>
>The fact is that the modern transistor must rely on NFB for it to be
>acceptable in any way.

The fact is that you have your facts wrong. Can you not *read* what is
plainly written above?

>Every transistor amp must use a lot more NFB to be acceptable than the NFB
>that is within
>a tube such as a 6SN7.

Utter bull****, see my other post in this thread about the 2SA1216 and
2SC2922.

>You are entitled to your opinion, but I cannot agree.

You have the right to be wrong - and you do love to exercise that
right!

>I delete the rest of your silly post; you come here like the pork seller to
>the synagogue to sell your pork,
>and I ain't buying.

I know a couple of Jews who'd buy - but maybe not while in schul. :-)

>Does it ever occur that you entirely waste your time and ours by trying to
>hang out around here?

Not really, as some passing newbie might need a reality check, which
he sure isn't going to get from you or Jute!
--

Stewart Pinkerton | Music is Art - Audio is Engineering

[Stewart Pinkerton]

On Mon, 27 Mar 2006 18:07:33 +0300, "Iain Churches"
> wrote:

>
>"Stewart Pinkerton" > wrote in message
...
>> On 26 Mar 2006 17:16:29 -0800, "Andre Jute" > wrote:
>>
>>>Wilson, you're getting nuttier and nuttier. First you claim my opinions
>>>and some really basic, totally uncontroversial science are lies because
>>>I haven't dotted thousands of tees you claim make your contrary point.
>>>Now you want me to defend tubes against BJTs, which as far as I can
>>>tell are Blow Jobs by Transvestites.
>>
>> I notice you fail to address the fact that the modern BJT can be more
>> linear *without feedback* than your beloved DHTs. Surely a *true*
>> 'ultrafidelista' would see this as the Holy Grail of the 'silent'
>> amplifier? Better linearity and no humming heaters?
>
>Erm. Stewart. DHTs don't have "heaters" :-((

More typical Churches ignorance. Of course they have heaters - and one
of the (several) serious *problems* with the DHT is that it uses the
*same* lump of metal that is one of the electrodes, to carry the
heating current!

You might want to pop down to the clue shop and see what they have on
sale in the 'thermionic emission' section.........
--

Stewart Pinkerton | Music is Art - Audio is Engineering

[Nick Gorham]

Arny Krueger wrote:
> "Iain Churches" > wrote in message
>
>
>>
>>Erm. Stewart. DHTs don't have "heaters" :-((
>
>
> Yup, according to Iain, and contrary to popular belief, DHT does not stand
> for "Directly HEATED Triode".
>
>

Exactly, the emmissive surface is directly heated, so does not require a
separate heater. So they do not have a heater. Seems simple enough to me.

--
Nick

[Iain Churches]

"Arny Krueger" > wrote in message
...
> "Iain Churches" > wrote in message
>
>> "Stewart Pinkerton" >
>> wrote in message
>> ...
>>> On 26 Mar 2006 17:16:29 -0800, "Andre Jute"
>>> > wrote:
>>>> Wilson, you're getting nuttier and nuttier. First you
>>>> claim my opinions and some really basic, totally
>>>> uncontroversial science are lies because I haven't
>>>> dotted thousands of tees you claim make your contrary
>>>> point. Now you want me to defend tubes against BJTs,
>>>> which as far as I can tell are Blow Jobs by
>>>> Transvestites.
>>>
>>> I notice you fail to address the fact that the modern
>>> BJT can be more linear *without feedback* than your
>>> beloved DHTs. Surely a *true* 'ultrafidelista' would see
>>> this as the Holy Grail of the 'silent' amplifier? Better
>>> linearity and no humming heaters?
>>
>> Erm. Stewart. DHTs don't have "heaters" :-((
>
> Yup, according to Iain, and contrary to popular belief, DHT does not stand
> for "Directly HEATED Triode".

That's precisely it, Arny. They are directly heated, and so do not have
a heater, which is defined as a separate winding adjacent to but physically
separated from the cathode. You will find no such winding in a DHT.
>
I quote from Tremaine. I am told that the same definition can be found both
in RDH4, and Crowhurst But of course, Arny knows better.

Iain

[Arny Krueger]

"Nick Gorham" > wrote in message

> Arny Krueger wrote:
>> "Iain Churches" > wrote in message
>>
>>
>>>
>>> Erm. Stewart. DHTs don't have "heaters" :-((

>> Yup, according to Iain, and contrary to popular belief,
>> DHT does not stand for "Directly HEATED Triode".

> Exactly, the emmissive surface is directly heated, so
> does not require a separate heater.

Huh, since it is heated directly, there is no heater?

LOL!

> So they do not have a
> heater. Seems simple enough to me.

Seems like senseless wordplay to me.

[[email protected]]

"Bret Ludwig" > wrote in message
oups.com...
>
>>
>> We can do with a comedy section. You should be aware though
>> > that a couple of appearances in the comedy section of my netsite (once
>> > for his ignorance on power supplies (1), once for the same matter of
>> > distortion distribution that so upsets you (2)) cost Mike LeFevre
>> > two-thirds of his existing business and closed out several avenues to
>> > fame and riches just then opening up to him. Several years later he
>> > still hasn't recovered. I'm sure you've wept for him...
>>
>
> Andre Jute is not responsible for Mike Lefevre's woes.

Andre Jute/McCoy/Munchausen is barely responsible for himself let alone
anybody else's success or falure.

Mike Lefevre
> is. People got tired of his rank dishonesty and ineptitude. Andre got
> on the bandwagon when it became apparent he was going down. Not that
> Lefevre deserves any sympathy.
>
They have that in common.

[Andy Evans]

> So they do not have a
> heater. Seems simple enough to me.

Seems like senseless wordplay to me. >

Wordplay in a way - the word "heaters" is usually used for the heater
circuit of an indirectly heated valve, and is abbreviated to "h" (see
duncanamps etc etc) on base details. The word "filaments" is usually
used for DHTs and is abbreviated to "f" on base details. This is a
commonly followed convention and avoids mix-ups.

[Nick Gorham]

Arny Krueger wrote:
> "Nick Gorham" > wrote in message
>
>
>>Arny Krueger wrote:
>>
>>>"Iain Churches" > wrote in message

>>>
>>>
>>>>Erm. Stewart. DHTs don't have "heaters" :-((
>
>
>>>Yup, according to Iain, and contrary to popular belief,
>>>DHT does not stand for "Directly HEATED Triode".
>
>
>>Exactly, the emmissive surface is directly heated, so
>>does not require a separate heater.
>
>
> Huh, since it is heated directly, there is no heater?
>
> LOL!
>
>
>>So they do not have a
>>heater. Seems simple enough to me.
>
>
> Seems like senseless wordplay to me.
>
>

It is, and it would have been, if Stewart had simply accepted it as
such, and corrected his original posting to use the word filament. But
no, even that has to be argued until we all loose interest.

--
Nick

[Trevor Wilson]

"Patrick Turner" > wrote in message
...
> Andre remarked that ..........................
>
>> > Now you want me to defend tubes against BJTs, which as far as I can
>> > tell are Blow Jobs by Transvestites.
>
> A truly DIMWITTED Trevor Wilson replied.....
>
>>
>> **Nope. YOU claimed that triodes were the most linear amplification
>> device.
>> Up until the development of modern transistors, that may have been the
>> case.
>> It has not been the case for many years, however.
>
> Unfortunately, Trevor has been spewing this drivel about BJTs being more
> linear
> than triodes for years.

**Look at the spec sheets, Patrick. It's a fact. Ignore if you wish, but the
facts speak for themselves.


--
Trevor Wilson
www.rageaudio.com.au

[Stewart Pinkerton]

On Mon, 27 Mar 2006 21:36:49 +0100, Nick Gorham >
wrote:

>Arny Krueger wrote:
>> "Nick Gorham" > wrote in message
>>
>>
>>>Arny Krueger wrote:
>>>
>>>>"Iain Churches" > wrote in message

>>>>
>>>>
>>>>>Erm. Stewart. DHTs don't have "heaters" :-((
>>
>>
>>>>Yup, according to Iain, and contrary to popular belief,
>>>>DHT does not stand for "Directly HEATED Triode".
>>
>>
>>>Exactly, the emmissive surface is directly heated, so
>>>does not require a separate heater.
>>
>> Huh, since it is heated directly, there is no heater?
>>
>> LOL!
>>
>>>So they do not have a
>>>heater. Seems simple enough to me.
>>
>> Seems like senseless wordplay to me.
>>
>It is, and it would have been, if Stewart had simply accepted it as
>such, and corrected his original posting to use the word filament. But
>no, even that has to be argued until we all loose interest.

But it is *not* senseless wordplay, as there's a fundamental
difference. In the DHT, the heater *is* the cathode, so you have to
take extreme measures to avoid introducing hum to the signal circuit.
Churches of course is just being his usual snide and ignorant self.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

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[Patrick Turner]

Arny Krueger wrote:

> "Patrick Turner" > wrote in message
>
>
> > They are only as linear as a triode with regard to
> > voltage gain when external loops of NFB have been applied,
> > as in the case of the emitter follower connection or
> > having a few BJTs with a loop of NFB around the
> > lot of them to correct all their mistakes.
>
> > BJTs are inherently non linear for voltage gain and MUST
> > rely on large amounts of externally connected loops of
> > NFB.
>
> Simply not true. Local feedback works well with BJTs.

Local loops are externally applied loops of NFB.

Bjts are so damned non linear with regard to voltage gain that large amount of
NFB, local or otherwises must be applied
to linearize the outcome, as well as raise input impedance.

>
>
> > This applies regardless of whether you build a preamp
> > with an opamp, a discrete transistor preamp,
> > or any power amp.
> >
> > Triodes don't, they have a small amount of NFB built into
> > them.
>
> Compared to BJTs, triodes have massive amounts of local NFB built into them,
> and they are often used with addtiional local and/or loop NFB.

You don't know how much NFB is within any given triode now do you?

Please provide some calculations and details to prove to the group that you have
the slightest idea about what you are talking about.

Keep your answer to less than 5,000 words.

>
>
> > I would ask Trevor to set up a simple 1 transistor preamp
> > with a BC109, and without any
> > NFB applied, not even an emitter current feedback
> > resistor, and as a common emitter voltage amplifier with
> > a supply of 20V.
>
> An apples-to-apples comparison would involve comparing circuits with gain
> and impedances, both input and output, that are as typical and similar as
> possible. However, this comparison is totally ludicrous, because nobody in
> their right mind uses a stand-alone BC109 as a high grade audio amplifier
> any more. They'll use some kind of an op amp, perhaps a NE 5532 or its
> equivalent.

It isn't ludicous to drag people screaming back to the basics.
The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR OTHERWISE applied anywhere
have hopelessly poor
voltage gain linearity.
Statements have been made on the group that what i am saying is untrue.

All opamps also must be used with NFB, and they contain many interconnected bjts
like many
discrete component amplifier, so the non linearity of all these adds together
and must be linearized with NFB.
opamps usually have way too much gain without NFB; and usually poor open loop
bandwidth,
something also flattened out by NFB.

>
> > To understand his own utter stupidity, I ask Trevor to
> > also set up a 6SN7 with a 250V supply to act as a preamp
> > and without any loop NFB, and he can then tell us all
> > about the results which will prove what a
> > jackarse he is.
>
> Illogical comparison. Everybody knows that 6SN7s have a ton of internal
> feedback, and that BJTs compare most closely to pentodes, not triodes.

A "ton" of NFB is an extremely uninformative unit applied to NFB.

Please try be specific and factual lest we consider you to be utterly stupid
like Trevor.

Exactly how much NFB is within a 6SN7?

I will also say that a 6AU6 pentode would be more linear at a volt of output
than a BC109 at a volt of output,
with both devices tested without NFB of any kind.

Unless you have done the experiments and comparisons, you remain uneducated
about the basics.

When people talk about the linearity of devices, what is being stated is the
linearity of the devices without
any external loops of NFB applied. That is what engineers understand when
somebody talks of device linearity.

bjts offer fair current linearity between base current and collector current but
offer hopeless
voltage linearity.
Amplifiers are built to provide voltage linearity regardless of current
variations due to load variations.

External loops in circuit applications of NFB are never included in discussions
defining device linearity.

You cannot say a bjt is linear if you are using an emitter follower as an
example of the device use.
The term "emitter follower" is a description of a circuit where a large amount
of series voltage NFB is
employed so that the voltage gain of the bjt is reduced from a disgustingly non
linear large number, say
100 times to say 0.99, and the open loop THD is reduced 100 times.

I will say to that where you have a 12AX7 set up as a cathode follower then
there is a gain reduction
of say 75 to just less than 1.0, so the linearity of the device cannot be known
without more provisos.

if you have an EF bjt circuit and THD = 0.01% at 1Vrms and if open loop gain was
100,
then the THD without the follower connection with the load used will be 100 x
0.01 = 1%.

The 1/2 12AX7 in a CF will typically produce only 0.0005% THD at 1V out.
If the same tube was working without the CF connection but in common cathode
the THD = 75 x 0.0005 = 0.0375%, and a small fraction of what is produced by the
BC109 without any NFB.




Patrick Turner.

[Patrick Turner]

Iain Churches wrote:

> "Stewart Pinkerton" > wrote in message
> ...
> > On 26 Mar 2006 17:16:29 -0800, "Andre Jute" > wrote:
> >
> >>Wilson, you're getting nuttier and nuttier. First you claim my opinions
> >>and some really basic, totally uncontroversial science are lies because
> >>I haven't dotted thousands of tees you claim make your contrary point.
> >>Now you want me to defend tubes against BJTs, which as far as I can
> >>tell are Blow Jobs by Transvestites.
> >
> > I notice you fail to address the fact that the modern BJT can be more
> > linear *without feedback* than your beloved DHTs. Surely a *true*
> > 'ultrafidelista' would see this as the Holy Grail of the 'silent'
> > amplifier? Better linearity and no humming heaters?
>
> Erm. Stewart. DHTs don't have "heaters" :-((

But the DHT's cathode is self heating and unless adequate steps are taken to
have
good hum nulling if the cathode has a mains F applied end to end then indeed
hum could be a bother.

Using IHT overcomes the problem.

But don't worry, I have to repair many BJT based amps with hum problems....

Patrick Turner.

>
>
> Iain

[Patrick Turner]

Arny Krueger wrote:

> "Patrick Turner" > wrote in message
>
> > Stewpid Oinkerton squealed....
> >
> >> I notice you fail to address the fact that the modern
> >> BJT can be more linear *without feedback* than your
> >> beloved DHTs. Surely a *true* 'ultrafidelista' would see
> >> this as the Holy Grail of the 'silent' amplifier? Better
> >> linearity and no humming heaters?
> >
> > The fact is that the modern transistor must rely on NFB
> > for it to be acceptable in any way.
>
> As do the vaccum-state devices that compare best to BJTs - pentodes.
>
> Turner wants us to think that using BJTs with emitter resistors is a crime
> of some kind.

I do not want this. Stop being an arsole by incorrectly stating what i want
readers to think.

I have designed built a considerable number of BJT based amplifiers. All rely
on NFB loops
to counter the terrible non-linearity of the BJTs with no NFB.

Patrick Turner

[Patrick Turner]

>
> > Unfortunately, Trevor has been spewing this drivel about BJTs being more
> > linear
> > than triodes for years.
>
> **Look at the spec sheets, Patrick. It's a fact. Ignore if you wish, but the
> facts speak for themselves.

You continue to spew drivel.

Patrick Turner.

[Arny Krueger]

"Patrick Turner" > wrote in message

> Arny Krueger wrote:
>
>> "Patrick Turner" > wrote in
>> message
>>
>>> They are only as linear as a triode with regard to
>>> voltage gain when external loops of NFB have been
>>> applied, as in the case of the emitter follower
>>> connection or having a few BJTs with a loop of NFB
>>> around the
>>> lot of them to correct all their mistakes.
>>
>>> BJTs are inherently non linear for voltage gain and MUST
>>> rely on large amounts of externally connected loops of
>>> NFB.
>>
>> Simply not true. Local feedback works well with BJTs.
>
> Local loops are externally applied loops of NFB.

External to the device, but not external to the stage of amplification.

> Bjts are so damned non linear with regard to voltage gain
> that large amount of NFB, local or otherwises must be
> applied to linearize the outcome, as well as raise input
> impedance.

So what? In the end BJTs can be, with a trivial amount of effort, be used to
make the most linear amplifiers known to man.

>>> This applies regardless of whether you build a preamp
>>> with an opamp, a discrete transistor preamp,
>>> or any power amp.
>>>
>>> Triodes don't, they have a small amount of NFB built
>>> into them.

>> Compared to BJTs, triodes have massive amounts of local
>> NFB built into them, and they are often used with
>> addtiional local and/or loop NFB.

> You don't know how much NFB is within any given triode
> now do you?

In the case of triode-connected pentodes, the amount of NFB is exactly
knowable. Just reconnect as a pentode.

But it doesn't matter because nobody in their right mind who is out to
design the lowest distortion amp around is going to use tubes.

> Please provide some calculations and details to prove to
> the group that you have the slightest idea about what you
> are talking about.

Asked and answered.

> Keep your answer to less than 5,000 words.

Been there, done that.

>>> I would ask Trevor to set up a simple 1 transistor
>>> preamp with a BC109, and without any
>>> NFB applied, not even an emitter current feedback
>>> resistor, and as a common emitter voltage amplifier with
>>> a supply of 20V.
>>
>> An apples-to-apples comparison would involve comparing
>> circuits with gain and impedances, both input and
>> output, that are as typical and similar as possible.
>> However, this comparison is totally ludicrous, because
>> nobody in their right mind uses a stand-alone BC109 as a
>> high grade audio amplifier any more. They'll use some
>> kind of an op amp, perhaps a NE 5532 or its equivalent.

> It isn't ludicous to drag people screaming back to the
> basics.
> The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR
> OTHERWISE applied anywhere have hopelessly poor
> voltage gain linearity.

It doesn't seem to matter, does it. In fact the lowest distortion amps
around are SS, not tubes. In fact every modern recording console of
substance is based on SS. Every modern music player is based on SS.

> Statements have been made on the group that what i am
> saying is untrue.

I've mostly said the truth about your statements, Patrick: They are
irrelevant.

> All opamps also must be used with NFB, and they contain
> many interconnected bjts like many
> discrete component amplifier, so the non linearity of all
> these adds together and must be linearized with NFB.
> opamps usually have way too much gain without NFB; and
> usually poor open loop bandwidth,
> something also flattened out by NFB.

So what? There is no such thing as a tubed amplifier that is even 1/10 as
linear as a $0.25 op amp, as said op amp is typically used.

>>> To understand his own utter stupidity, I ask Trevor to
>>> also set up a 6SN7 with a 250V supply to act as a preamp
>>> and without any loop NFB, and he can then tell us all
>>> about the results which will prove what a
>>> jackarse he is.

>> Illogical comparison. Everybody knows that 6SN7s have a
>> ton of internal feedback, and that BJTs compare most
>> closely to pentodes, not triodes.

> A "ton" of NFB is an extremely uninformative unit applied
> to NFB.

OK, its more like 1,000 KG. ;-)

> Please try be specific and factual lest we consider you
> to be utterly stupid like Trevor.

> Exactly how much NFB is within a 6SN7?

It's not practically knowable, and its irrelevant on the best day of its
life.

> I will also say that a 6AU6 pentode would be more linear
> at a volt of output than a BC109 at a volt of output,
> with both devices tested without NFB of any kind.

Say what you will Patrick. Your challenge is finding anybody with a brain
who cares.

> Unless you have done the experiments and comparisons, you
> remain uneducated about the basics.

The facts are before us. Nobody in their right mind who wants the most
linear amplifier uses tubes. Tubed amplifiers are mostly used in the 21st
century as EFX boxes.

> When people talk about the linearity of devices, what is
> being stated is the linearity of the devices without
> any external loops of NFB applied. That is what engineers
> understand when somebody talks of device linearity.

It doesn't matter. Consumers don't care what the parts inside a box do, they
care about what the box does.

> bjts offer fair current linearity between base current
> and collector current but offer hopeless
> voltage linearity.

So, use feedback to linearize them. Where's the beef?

> Amplifiers are built to provide voltage linearity
> regardless of current variations due to load variations.

Thanks for agreeing with my claim that consumers don't care what the parts
inside a box do, they care about what the box does.


> External loops in circuit applications of NFB are never
> included in discussions defining device linearity.

So what?

> You cannot say a bjt is linear if you are using an
> emitter follower as an example of the device use.
> The term "emitter follower" is a description of a circuit
> where a large amount of series voltage NFB is
> employed so that the voltage gain of the bjt is reduced
> from a disgustingly non linear large number, say
> 100 times to say 0.99, and the open loop THD is reduced
> 100 times.

I see a dead horse being flogged very energetically. One word: Why?

[Stewart Pinkerton]

On Tue, 28 Mar 2006 09:09:02 GMT, Patrick Turner
> wrote:

>
>
>Arny Krueger wrote:
>
>> "Patrick Turner" > wrote in message
>>
>> > Stewpid Oinkerton squealed....
>> >
>> >> I notice you fail to address the fact that the modern
>> >> BJT can be more linear *without feedback* than your
>> >> beloved DHTs. Surely a *true* 'ultrafidelista' would see
>> >> this as the Holy Grail of the 'silent' amplifier? Better
>> >> linearity and no humming heaters?
>> >
>> > The fact is that the modern transistor must rely on NFB
>> > for it to be acceptable in any way.
>>
>> As do the vaccum-state devices that compare best to BJTs - pentodes.
>>
>> Turner wants us to think that using BJTs with emitter resistors is a crime
>> of some kind.
>
>I do not want this. Stop being an arsole by incorrectly stating what i want
>readers to think.
>
>I have designed built a considerable number of BJT based amplifiers. All rely
>on NFB loops
>to counter the terrible non-linearity of the BJTs with no NFB.

Try building KISASS - it uses a BJT which is *inherently* more linear
than a 3090B, the 2SC2922. No feedback required.....
--

Stewart Pinkerton | Music is Art - Audio is Engineering

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[Stewart Pinkerton]

On Tue, 28 Mar 2006 09:14:50 GMT, Patrick Turner
> wrote:

>>
>> > Unfortunately, Trevor has been spewing this drivel about BJTs being more
>> > linear
>> > than triodes for years.
>>
>> **Look at the spec sheets, Patrick. It's a fact. Ignore if you wish, but the
>> facts speak for themselves.
>
>You continue to spew drivel.

You continue to ignore the evidence of the spec sheet. Why? Is it
against your tube religion that triodes are in fact *not* the most
linear active devices available? See if you can find any triode which
is more linear than a 2SA1216.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

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[Stewart Pinkerton]

On Tue, 28 Mar 2006 08:59:43 GMT, Patrick Turner
> wrote:

>
>
>Arny Krueger wrote:
>
>> "Patrick Turner" > wrote in message
>>
>>
>> > They are only as linear as a triode with regard to
>> > voltage gain when external loops of NFB have been applied,
>> > as in the case of the emitter follower connection or
>> > having a few BJTs with a loop of NFB around the
>> > lot of them to correct all their mistakes.
>>
>> > BJTs are inherently non linear for voltage gain and MUST
>> > rely on large amounts of externally connected loops of
>> > NFB.
>>
>> Simply not true. Local feedback works well with BJTs.
>
>Local loops are externally applied loops of NFB.
>
>Bjts are so damned non linear with regard to voltage gain that large amount of
>NFB, local or otherwises must be applied
>to linearize the outcome, as well as raise input impedance.

Some BJTs are more linear than say a 300B. Why do you keep ignoring
this *fact*. Heresy?

>It isn't ludicous to drag people screaming back to the basics.
>The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR OTHERWISE applied anywhere
>have hopelessly poor
>voltage gain linearity.

Utter bunk, check the spec sheet for the 2SA1216. Gain linearity is
flat as a pancake at elevated junction temperatures, as would be
experienced in a Class A amplifier.

>Statements have been made on the group that what i am saying is untrue.

That's because it is - see above.

>All opamps also must be used with NFB, and they contain many interconnected bjts
>like many
>discrete component amplifier, so the non linearity of all these adds together
>and must be linearized with NFB.
>opamps usually have way too much gain without NFB; and usually poor open loop
>bandwidth,
>something also flattened out by NFB.

Opamps are *designed* to be used with large amounts of NFB, and a
decent audio opamp such as the B-B OPA2604 is much more linear than
any tube (or combination of tubes) at the same stage gain. How you get
to there doesn't matter, it's the 'black box' performance that counts.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

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[Ruud Broens]

"Stewart Pinkerton" > wrote in message
...
: On Tue, 28 Mar 2006 08:59:43 GMT, Patrick Turner
: > wrote:
:
: >
: >
: >Arny Krueger wrote:
: >
: >> "Patrick Turner" > wrote in message
: >>
: >>
: >> > They are only as linear as a triode with regard to
: >> > voltage gain when external loops of NFB have been applied,
: >> > as in the case of the emitter follower connection or
: >> > having a few BJTs with a loop of NFB around the
: >> > lot of them to correct all their mistakes.
: >>
: >> > BJTs are inherently non linear for voltage gain and MUST
: >> > rely on large amounts of externally connected loops of
: >> > NFB.
: >>
: >> Simply not true. Local feedback works well with BJTs.
: >
: >Local loops are externally applied loops of NFB.
: >
: >Bjts are so damned non linear with regard to voltage gain that large amount of
: >NFB, local or otherwises must be applied
: >to linearize the outcome, as well as raise input impedance.
:
: Some BJTs are more linear than say a 300B. Why do you keep ignoring
: this *fact*. Heresy?
:
: >It isn't ludicous to drag people screaming back to the basics.
: >The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR OTHERWISE applied
anywhere
: >have hopelessly poor
: >voltage gain linearity.
:
: Utter bunk, check the spec sheet for the 2SA1216. Gain linearity is
: flat as a pancake at elevated junction temperatures, as would be
: experienced in a Class A amplifier.


yep, checking, i found it here:
http://users.otenet.gr/~athsam/database.htm

the third graph shows Vbe - Ic, the _run hot_ curve
does 0.8 V Vbe @ 6 A, 400 mVtt giving 6 Att with 1.6 % distortion
certainly impressive. but, now realize the curves are taken at a
constant Vce=4V - not very realistic, is it ?

now, Hfe about 100, at this 24W class A idle point,
60 mA of base current is required. oops, at 10 A, Hfe has
gone south to only 60, creating an additional few dozens
of THD %.

2nd take:
0.6Vbe, 2.2 A idle now Hfe stays flat with 200 mVtt in, 4Att out,
distortion is 7 % or so that's indeed quite an achievement

but considering it's taken at constant Vce
reality will be worse

: >Statements have been made on the group that what i am saying is untrue.
:
: That's because it is - see above.

hm, about 12 W / 8 Ohm available, > 7 % THD, 8.8 W idle with the 2SA1216
you're saying there are no tubes that can beat that ?
hmmm

the truth,
Rudy
: --
:
: Stewart Pinkerton | Music is Art - Audio is Engineering

: http://www.usenet.com

[Ruud Broens]

"Stewart Pinkerton" > wrote in message
...
:
: Try building KISASS - it uses a BJT which is *inherently* more linear
: than a 3090B, the 2SC2922. No feedback required.....
: --
:
: Stewart Pinkerton | Music is Art - Audio is Engineering

the 3090B ?
you mean, the 300 kW pulse TPS3 radar tube ??
~ http://www.r-type.org/exhib/aac0090.htm ~
You've tried *that* for comparison ???

yah, right :-)

Rudy

[Ruud Broens]

"Stewart Pinkerton" > wrote in message
...
: On Tue, 28 Mar 2006 09:14:50 GMT, Patrick Turner
: > wrote:
:
: >>
: >> > Unfortunately, Trevor has been spewing this drivel about BJTs being more
: >> > linear
: >> > than triodes for years.
: >>
: >> **Look at the spec sheets, Patrick. It's a fact. Ignore if you wish, but the
: >> facts speak for themselves.
: >
: >You continue to spew drivel.
:
: You continue to ignore the evidence of the spec sheet. Why? Is it
: against your tube religion that triodes are in fact *not* the most
: linear active devices available? See if you can find any triode which
: is more linear than a 2SA1216.
: --
:
: Stewart Pinkerton | Music is Art - Audio is Engineering

yawn. 7 % + distortion with magic power efficiency numbers ?
been there,
seen it.

got any real world numbers ?




thought not

R.

[Stewart Pinkerton]

On Tue, 28 Mar 2006 23:07:46 +0200, "Ruud Broens" >
wrote:

>
>"Stewart Pinkerton" > wrote in message
...
>: On Tue, 28 Mar 2006 08:59:43 GMT, Patrick Turner
>: > wrote:
>:
>: >
>: >
>: >Arny Krueger wrote:
>: >
>: >> "Patrick Turner" > wrote in message
>: >>
>: >>
>: >> > They are only as linear as a triode with regard to
>: >> > voltage gain when external loops of NFB have been applied,
>: >> > as in the case of the emitter follower connection or
>: >> > having a few BJTs with a loop of NFB around the
>: >> > lot of them to correct all their mistakes.
>: >>
>: >> > BJTs are inherently non linear for voltage gain and MUST
>: >> > rely on large amounts of externally connected loops of
>: >> > NFB.
>: >>
>: >> Simply not true. Local feedback works well with BJTs.
>: >
>: >Local loops are externally applied loops of NFB.
>: >
>: >Bjts are so damned non linear with regard to voltage gain that large amount of
>: >NFB, local or otherwises must be applied
>: >to linearize the outcome, as well as raise input impedance.
>:
>: Some BJTs are more linear than say a 300B. Why do you keep ignoring
>: this *fact*. Heresy?
>:
>: >It isn't ludicous to drag people screaming back to the basics.
>: >The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR OTHERWISE applied
>anywhere
>: >have hopelessly poor
>: >voltage gain linearity.
>:
>: Utter bunk, check the spec sheet for the 2SA1216. Gain linearity is
>: flat as a pancake at elevated junction temperatures, as would be
>: experienced in a Class A amplifier.
>
>
>yep, checking, i found it here:
>http://users.otenet.gr/~athsam/database.htm
>
>the third graph shows Vbe - Ic, the _run hot_ curve
>does 0.8 V Vbe @ 6 A, 400 mVtt giving 6 Att with 1.6 % distortion
> certainly impressive. but, now realize the curves are taken at a
>constant Vce=4V - not very realistic, is it ?
>
>now, Hfe about 100, at this 24W class A idle point,
>60 mA of base current is required. oops, at 10 A, Hfe has
>gone south to only 60, creating an additional few dozens
>of THD %.
>
>2nd take:
>0.6Vbe, 2.2 A idle now Hfe stays flat with 200 mVtt in, 4Att out,
>distortion is 7 % or so that's indeed quite an achievement
>
>but considering it's taken at constant Vce
>reality will be worse
>
>: >Statements have been made on the group that what i am saying is untrue.
>:
>: That's because it is - see above.
>
>hm, about 12 W / 8 Ohm available, > 7 % THD, 8.8 W idle with the 2SA1216
>you're saying there are no tubes that can beat that ?

I read less than that into those curves, but even if true, that's
better than you'll get with the 300B.

You are of course conveniently forgetting something else, the greatly
superior gain of the 2SA216. In the KISASS design, Tr2, the equivalent
of the 300B in KISS, has its emitter and collector loads set for a
stage gain of 6.25, to make it as similar as possible to the KISS amp.
This applies more than 20dB of local regeneration, equivalent to the
internal feedback of the 300B, cutting the distortion to about 0.5%.
Apples to apples, KISASS totally outperforms KISS.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

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[Patrick Turner]

>

I asked Arnie....

>
> > You don't know how much NFB is within any given triode
> > now do you?
>
> In the case of triode-connected pentodes, the amount of NFB is exactly
> knowable. Just reconnect as a pentode.

But you can't do that with a real triode.

I repeat, how much NFB is there in a triode?

>
> But it doesn't matter because nobody in their right mind who is out to
> design the lowest distortion amp around is going to use tubes.

Irrelevant.

>
>
> > Please provide some calculations and details to prove to
> > the group that you have the slightest idea about what you
> > are talking about.
>
> Asked and answered.
>
> > Keep your answer to less than 5,000 words.
>
> Been there, done that.

You most certainly have not.
You are showing your ignorance and I see no reason to read any more of your
post.

Patrick Turner.

[Andre Jute]

Ruud Broens wrote:

> "Stewart Pinkerton" > wrote in message
> ...
> : On Tue, 28 Mar 2006 08:59:43 GMT, Patrick Turner
> : > wrote:
> :
> : >
> : >
> : >Arny Krueger wrote:
> : >
> : >> "Patrick Turner" > wrote in message
> : >>
> : >>
> : >> > They are only as linear as a triode with regard to
> : >> > voltage gain when external loops of NFB have been applied,
> : >> > as in the case of the emitter follower connection or
> : >> > having a few BJTs with a loop of NFB around the
> : >> > lot of them to correct all their mistakes.
> : >>
> : >> > BJTs are inherently non linear for voltage gain and MUST
> : >> > rely on large amounts of externally connected loops of
> : >> > NFB.
> : >>
> : >> Simply not true. Local feedback works well with BJTs.
> : >
> : >Local loops are externally applied loops of NFB.
> : >
> : >Bjts are so damned non linear with regard to voltage gain that large amount of
> : >NFB, local or otherwises must be applied
> : >to linearize the outcome, as well as raise input impedance.
> :
> : Some BJTs are more linear than say a 300B. Why do you keep ignoring
> : this *fact*. Heresy?
> :
> : >It isn't ludicous to drag people screaming back to the basics.
> : >The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR OTHERWISE applied
> anywhere
> : >have hopelessly poor
> : >voltage gain linearity.
> :
> : Utter bunk, check the spec sheet for the 2SA1216. Gain linearity is
> : flat as a pancake at elevated junction temperatures, as would be
> : experienced in a Class A amplifier.
>
>
> yep, checking, i found it here:
> http://users.otenet.gr/~athsam/database.htm
>
> the third graph shows Vbe - Ic, the _run hot_ curve
> does 0.8 V Vbe @ 6 A, 400 mVtt giving 6 Att with 1.6 % distortion
> certainly impressive. but, now realize the curves are taken at a
> constant Vce=4V - not very realistic, is it ?
>
> now, Hfe about 100, at this 24W class A idle point,
> 60 mA of base current is required. oops, at 10 A, Hfe has
> gone south to only 60, creating an additional few dozens
> of THD %.
>
> 2nd take:
> 0.6Vbe, 2.2 A idle now Hfe stays flat with 200 mVtt in, 4Att out,
> distortion is 7 % or so that's indeed quite an achievement
>
> but considering it's taken at constant Vce
> reality will be worse
>
> : >Statements have been made on the group that what i am saying is untrue.
> :
> : That's because it is - see above.
>
> hm, about 12 W / 8 Ohm available, > 7 % THD, 8.8 W idle with the 2SA1216
> you're saying there are no tubes that can beat that ?
> hmmm
>
> the truth,
> Rudy

Sheesh, Rudy, this BJT the silicon clowns want to flog you isn't much
chop; in fact it appears to be just a "modern" device number assigned
to the same old silicon excrement I rejected forty years ago. A modern
300B amp, designed with high voltage, high current and high bias in the
modern Jute style has *less* distortion at full power, and practically
no 3rd harmonic distortion. I show the results of a challenge to me by
another incompetent pair of idiots. "BobC" Chernofsky and Michael
LeFevre of Magnequest Transformers. Note that even an incompetently
designed 300B such as the Bubbaland 300Bis still a more attractive
(lower odd harmonics) amplifying device than the sliver of silicon ****
this street-seller of crisped porkfat is trying to palm off on you.


Table reads right in Courier 10 pt.

Bob C's "Bubbaland" Andre's "Hedonist"

Grid Plate Grid Plate
Voltage Current (mA) Voltage Current (mA)
0.0 102 0.0 136
-22.3 87 -23.4 119
-76.0 50 -80.0 80
-129.7 18 -136.6 44
-152.0 6 -160.0 30

Load Resistance 5,000 Load Resistance 5,000
Supply Voltage 350 Supply Voltage 390
Plate Dissipation 17.5 Plate Dissipation 31.2
Power Output 5.9 Power Output 7.0
% 2nd Harmonic 4.13 % 2nd Harmonic 2.83
% 3rd Harmonic 0.82 % 3rd Harmonic 0.03

(Table courtesy of John Byrns)

******
Of course, while a silicon amp might be designed to use with
incompently insensitive speakers and will thus *require* all its power,
a tube amp like those above (including the now apparently--by
comparison to the silicon PinkoStinko is trying to flog--not quite so
incompetent Chernofsky/LeFevre noise generator), is created as part of
a chain designed back from highly sensitive speakers (both the above
amps were designed for use with Lowther horns). Thus the normal mode of
the transistor might be flat out while the 300B will idle on
milliwatts, with vanishing distortion; that is why this class of tube
amp is normally specified at the 1W it will never in normal working
see, and the transistor device at full chat.

Doesn't seem to be anything left to say, does there? (Unless one wants
to gloat, and we'd never do that, would we?)

Hell, our legislators managed to criminalize fox hunting and smoking; I
wonder when they will get off their collective fat arse and criminalize
negative feedback. It is clearly consumed only by undesirables.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

[Andre Jute]

Iain Churches wrote:
> "Patrick Turner" > wrote in message
> ...
> >
> > Iain Churches wrote:
> >
> >> So, a thread from Trevor, on the subject of NFB and stability
> >> would be of interest to many I think.
> >
> > I doubt if Trevor could do any better than feign interest in any tube
> > discussion.
> > We all know he is insincere though.
>
> Let's see if he starts the NFB thread.

Wilson won't. There's a pattern here. Pinkerton, offered an opportunity
to design a tube amp to prove he knows more than we do, refused on the
ground that it would be "nitpicked to death". Wilson obviously has all
the time in the world to write thousands of words about my articles, to
iterate his silly demands that Patrick or I write about the intricacies
of NFB yet again. But when he is invited to contribute an article on
NFB, he claims's he's too busy. Pearce, Krueger, all the other flame
merchants, contribute nothing in their soundbites. Apparently they want
to nitpick everyone else to death but cannot bear exposing themselves
to criticism. They're probably right. If they ever tried to do what
Patrick Turner and John Byrns and you and I do daily, namely actually
explain things, we would soon discover how much they know. They clearly
fear that we will discover they know very little.

> I am a little mystified by the people who spend time on this forum
> and yet have no interest whatsoever, and nothing to contribute on
> the subject of tube audio. Why do they bother?

It's an easy thing to explain for anyone who grew up in a small town.
Wilson, Pinkerton, Krueger, Pearce, and assorted hangers-on like
McKelvy, Wieck, etc, are dried up old maids. twitching their net
curtains, peering out at people having fun, pursing their sour little
mouths and calling the vicar to stop the parade. Their preference of
silicon is dead -- or they believe it is -- with nothing left to decide
except whether Bose or Apple will inherit the remains. There is no
interest left in silicon -- and can you actually believe that such arid
people ever really loved music? -- so our glee in our tubes is doubly
offensive to them, a condition aggravated by the malice ingrained in
their petty, spiteful personalities.

In short, this scum is hounding us for the same reason that school
bullies take the marbles from smaller boys: not because they really
want the marbles but for the sick satisfaction of denying someone else
pleasure. I would bet a year of Pinkerton's salary that every one of
them pulled the wings from butterflies when they were boys.

Andre Jute

[Andre Jute]

Andre Jute wrote:
> Iain Churches wrote:
> > "Patrick Turner" > wrote in message
> > ...
> > >
> > > Iain Churches wrote:
> > >
> > >> So, a thread from Trevor, on the subject of NFB and stability
> > >> would be of interest to many I think.
> > >
> > > I doubt if Trevor could do any better than feign interest in any tube
> > > discussion.
> > > We all know he is insincere though.
> >
> > Let's see if he starts the NFB thread.
>
> Wilson won't. There's a pattern here. Pinkerton, offered an opportunity
> to design a tube amp to prove he knows more than we do, refused on the
> ground that it would be "nitpicked to death". Wilson obviously has all
> the time in the world to write thousands of words about my articles, to
> iterate his silly demands that Patrick or I write about the intricacies
> of NFB yet again. But when he is invited to contribute an article on
> NFB, he claims's he's too busy. Pearce, Krueger, all the other flame
> merchants, contribute nothing in their soundbites. Apparently they want
> to nitpick everyone else to death but cannot bear exposing themselves
> to criticism. They're probably right. If they ever tried to do what
> Patrick Turner and John Byrns and you and I do daily, namely actually
> explain things, we would soon discover how much they know. They clearly
> fear that we will discover they know very little.
>
> > I am a little mystified by the people who spend time on this forum
> > and yet have no interest whatsoever, and nothing to contribute on
> > the subject of tube audio. Why do they bother?
>
> It's an easy thing to explain for anyone who grew up in a small town.
> Wilson, Pinkerton, Krueger, Pearce, and assorted hangers-on like
> McKelvy, Wieck, etc, are dried up old maids. twitching their net
> curtains, peering out at people having fun, pursing their sour little
> mouths and calling the vicar to stop the parade. Their preference of
> silicon is dead -- or they believe it is -- with nothing left to decide
> except whether Bose or Apple will inherit the remains. There is no
> interest left in silicon -- and can you actually believe that such arid
> people ever really loved music? -- so our glee in our tubes is doubly
> offensive to them, a condition aggravated by the malice ingrained in
> their petty, spiteful personalities.
>
> In short, this scum is hounding us for the same reason that school
> bullies take the marbles from smaller boys: not because they really
> want the marbles but for the sick satisfaction of denying someone else
> pleasure. I would bet a year of Pinkerton's salary that every one of
> them pulled the wings from butterflies when they were boys.
>
> Andre Jute

[Andy Evans]

Amplifiers with no NFB (except for what is locally inherent in the
devices, particularly triode tubes) usually sound queefy >

Not sure what queefy is, but I know very well what amps with no NFB
sound like, and I'm NOT SAYING. So there.

[Ruud Broens]

"Stewart Pinkerton" > wrote in message
...
: On Tue, 28 Mar 2006 23:07:46 +0200, "Ruud Broens" >
: wrote:
:
: >
: >: >Bjts are so damned non linear with regard to voltage gain that large amount
of
: >: >NFB, local or otherwises must be applied
: >: >to linearize the outcome, as well as raise input impedance.
: >:
: >: Some BJTs are more linear than say a 300B. Why do you keep ignoring
: >: this *fact*. Heresy?
: >:
: >: >It isn't ludicous to drag people screaming back to the basics.
: >: >The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR OTHERWISE applied
: >anywhere
: >: >have hopelessly poor
: >: >voltage gain linearity.
: >:
: >: Utter bunk, check the spec sheet for the 2SA1216. Gain linearity is
: >: flat as a pancake at elevated junction temperatures, as would be
: >: experienced in a Class A amplifier.
: >
: >
: >yep, checking, i found it here:
: >http://users.otenet.gr/~athsam/database.htm
: >
: >the third graph shows Vbe - Ic, the _run hot_ curve
: >does 0.8 V Vbe @ 6 A, 400 mVtt giving 8 Att with 1.6 % distortion
: > certainly impressive. but, now realize the curves are taken at a
: >constant Vce=4V - not very realistic, is it ?
: >
: >now, Hfe about 100, at this 24W class A idle point,
: >60 mA of base current is required. oops, at 10 A, Hfe has
: >gone south to only 60, creating an additional few dozens
: >of THD %.
: >
: >2nd take:
: >0.6Vbe, 2.2 A idle now Hfe stays flat with 200 mVtt in, 4Att out,
: >distortion is 7 % or so that's indeed quite an achievement
: >
: >but considering it's taken at constant Vce
: >reality will be worse
: >
: >: >Statements have been made on the group that what i am saying is untrue.
: >:
: >: That's because it is - see above.
: >
: >hm, about 12 W / 8 Ohm available, > 7 % THD, 8.8 W idle with the 2SA1216
: >you're saying there are no tubes that can beat that ?
:
: I read less than that into those curves, but even if true, that's
: better than you'll get with the 300B.
:
: You are of course conveniently forgetting something else, the greatly
: superior gain of the 2SA216. In the KISASS design, Tr2, the equivalent
: of the 300B in KISS, has its emitter and collector loads set for a
: stage gain of 6.25, to make it as similar as possible to the KISS amp.
: This applies more than 20dB of local regeneration, equivalent to the
: internal feedback of the 300B, cutting the distortion to about 0.5%.
: Apples to apples, KISASS totally outperforms KISS.
:
: --
:
: Stewart Pinkerton | Music is Art - Audio is Engineering

not forgetting anything here, just sticking with the topic - again -
being inherent device linearity, not what you can do with fb - remember ?

it seems you didn't get the impossibility to create 12W out with 8.8 W idle
class A, the '-4V Vce from the graph' * 2.2 A idle
to make it work for an 8 Ohm, 12 W output, you'll actually need about
40V supply voltage and a current sink pulling 2.2A, together using 88W
to get that 12W out - 15 % efficiency and a large 1K/W heatsink for
that 2SA1216 and say an LM350.

you are also conveniently forgetting that - as is -, you have an input
impedance of about 5 Ohms ...

more of a win some - loose some scenario, it seems,
Stewart ;-)

Rudy

[Roy]

"Andre Jute" > wrote in message
oups.com...
>
>
>> I am a little mystified by the people who spend time on this forum
>> and yet have no interest whatsoever, and nothing to contribute on
>> the subject of tube audio. Why do they bother?

Dear Mr Jute,

From this comment and from a similar view you posted in another thread, it
seems your main issue is with "non-glassheads" coming onto your beloved
hobby group RAT with their anti valve (sorry tube) views. Why then do you
not make your responses on that group only? Why do you feel the need to
spread your contributions across other groups too (especially UKRA)?

Roy.

[Stewart Pinkerton]

On Wed, 29 Mar 2006 15:32:14 +0200, "Ruud Broens" >
wrote:

>
>"Stewart Pinkerton" > wrote in message
...
>: On Tue, 28 Mar 2006 23:07:46 +0200, "Ruud Broens" >
>: wrote:
>:
>: >
>: >: >Bjts are so damned non linear with regard to voltage gain that large amount
>of
>: >: >NFB, local or otherwises must be applied
>: >: >to linearize the outcome, as well as raise input impedance.
>: >:
>: >: Some BJTs are more linear than say a 300B. Why do you keep ignoring
>: >: this *fact*. Heresy?
>: >:
>: >: >It isn't ludicous to drag people screaming back to the basics.
>: >: >The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR OTHERWISE applied
>: >anywhere
>: >: >have hopelessly poor
>: >: >voltage gain linearity.
>: >:
>: >: Utter bunk, check the spec sheet for the 2SA1216. Gain linearity is
>: >: flat as a pancake at elevated junction temperatures, as would be
>: >: experienced in a Class A amplifier.
>: >
>: >
>: >yep, checking, i found it here:
>: >http://users.otenet.gr/~athsam/database.htm
>: >
>: >the third graph shows Vbe - Ic, the _run hot_ curve
>: >does 0.8 V Vbe @ 6 A, 400 mVtt giving 8 Att with 1.6 % distortion
>: > certainly impressive. but, now realize the curves are taken at a
>: >constant Vce=4V - not very realistic, is it ?
>: >
>: >now, Hfe about 100, at this 24W class A idle point,
>: >60 mA of base current is required. oops, at 10 A, Hfe has
>: >gone south to only 60, creating an additional few dozens
>: >of THD %.
>: >
>: >2nd take:
>: >0.6Vbe, 2.2 A idle now Hfe stays flat with 200 mVtt in, 4Att out,
>: >distortion is 7 % or so that's indeed quite an achievement
>: >
>: >but considering it's taken at constant Vce
>: >reality will be worse
>: >
>: >: >Statements have been made on the group that what i am saying is untrue.
>: >:
>: >: That's because it is - see above.
>: >
>: >hm, about 12 W / 8 Ohm available, > 7 % THD, 8.8 W idle with the 2SA1216
>: >you're saying there are no tubes that can beat that ?
>:
>: I read less than that into those curves, but even if true, that's
>: better than you'll get with the 300B.
>:
>: You are of course conveniently forgetting something else, the greatly
>: superior gain of the 2SA216. In the KISASS design, Tr2, the equivalent
>: of the 300B in KISS, has its emitter and collector loads set for a
>: stage gain of 6.25, to make it as similar as possible to the KISS amp.
>: This applies more than 20dB of local regeneration, equivalent to the
>: internal feedback of the 300B, cutting the distortion to about 0.5%.
>: Apples to apples, KISASS totally outperforms KISS.
>:
>: --
>:
>: Stewart Pinkerton | Music is Art - Audio is Engineering
>
>not forgetting anything here, just sticking with the topic - again -
>being inherent device linearity, not what you can do with fb - remember ?

Yes, but PT already conceded that the 300B has internal feedback, so
he had no problem with local degeneration in KISASS. After all,
putting in a larger emitter resistor doesn't create any of the
supposed horrors of loop feedback. Note also that you already conceded
that it's as good or better than a 300B, without *any* feedback.

>it seems you didn't get the impossibility to create 12W out with 8.8 W idle
>class A, the '-4V Vce from the graph' * 2.2 A idle.

Sure I got it, but obviously KISASS doesn't use a 4 volt rail.....

>to make it work for an 8 Ohm, 12 W output, you'll actually need about
>40V supply voltage and a current sink pulling 2.2A, together using 88W
>to get that 12W out - 15 % efficiency and a large 1K/W heatsink for
>that 2SA1216 and say an LM350.

See KISASS, if you can't remember the basic parameters of KISS.
KISASS runs a 30 volt rail at the voltage amplifier, and is designed
to run 100 mA idle current in the voltage amplifier stage.

To reiterate the design process:

KISASS came about as a suggestion by Iain Churches that I design a SS
equivalent of Andre Jute's (so far mythical) KISS design, supposedly a
single-ended tube amp with 300B output tube, a double-triode
input/driver stage, zero loop feedback, and an output of less than ten
watts. Ignoring a bunch of tube-centric 'rules' spouted by Patrick
Turner, I had a think about how this should be done.

In terms of parts count, we cannot beat the Nelson Pass ZEN design,
which uses a single MOSFET, so we will use BJTs, the 'bete noir' of
the tube fan. In terms of excellent performance from a minimal parts
count, we have the classic 1969 Linsley Hood design, which ticks most
of the boxes but does use global NFB.

Where to go from here? OK, let's start from the simplest possible gain
stage, a common-emitter BJT with emitter and collector loads (Tr2 in
the schematic, the 2SC2922 device is recommended). This will set the
transfer curve, and hence the sonic signature, of the amplifier. Such
a stage does of course have a quite low input impedance, so we place a
simple emitter follower buffer (Tr1, the MJE15028 will do, or any
other decent medium power NPN BJT) ahead of it to allow a wider choice
of source devices. The output impedance (as with the 300B) is much too
high to drive a loudspeaker, so we need an impedance transformer. As
one of the great advances of SS was that it allowed the removal of the
OPT, we will not use iron. A simple pair of emitter followers (Tr3 and
Tr4, for which the 2SC2922 and 2SA1216 will work well, but other
modern complementary pairs may substitute) provide output impedance
reduction without affecting voltage gain, and there we have the design
in a nutshell.

Further philosophical decisions were the avoidance of bootstrapping
from the output to the gain stage (that could be construed as loop
feedback), and the use of a heavily filtered power supply to keep the
noise floor clean. The latter was in the cause of maintaining the
'first watt is the most important' philosophy, without which this
design is utterly pointless. R15 and R16 reduce the rail voltage to
give a maximum output power of less than ten watts into loads between
8 and 4 ohms, meeting one of the principal design parameters, while
R12, R13 and R14 maintain the rail voltage of the gain stage at 5
volts higher than the output rail, allowing better driving of the
output while maintaining the natural transfer function of the gain
stage.

The bias current of the output stage is set to about 1 amp by R6,
while the quiescent output voltage point is set primarily by R1/R2.
This amplifier should be d.c. and thermally stable, but will reward
careful layout, particularly in the utilisation of the 'star earth'
philosophy, i.e. one central ground point to which all 'zero volt'
connections are made. Given this, I'd expect less than 0.1% THD plus
noise right across the audio band at an output of 1 watt into 4-8
ohms, rising to several per cent just below clipping, in the usual
'SET' style. The output impedance will also be in the half-ohm region
over most of the audio band.

In terms of construction, it should be noted that R15 and R16
dissipate 5 watts each, so should be at least ten-watt rated, while R5
dissipates about 3 watts, and should be at least a 5-watt component.
R12, R13 and R14 should be 2-watt rated, the others should be
half-watt metal films. Note that for thermal stability, D1, D2, Tr3
and Tr4 must share the same heatsink.

>you are also conveniently forgetting that - as is -, you have an input
>impedance of about 5 Ohms ...

See KISASS for the solution. Tubes use lotsa volts, BJTs use lotsa
milliamps, same thing in the end for the 'black box' solution.

>more of a win some - loose some scenario, it seems,
>Stewart ;-)

Not really, as KISS suffers similar problems. Naturally, one wouldn't
expect a tubie to acknowledge this.

T reiterate
--

Stewart Pinkerton | Music is Art - Audio is Engineering

[Andre Jute]

Roy wrote:
> "Andre Jute" > wrote in message
> oups.com...
> >
> >
> >> I am a little mystified by the people who spend time on this forum
> >> and yet have no interest whatsoever, and nothing to contribute on
> >> the subject of tube audio. Why do they bother?
>
> Dear Mr Jute,
>
> From this comment and from a similar view you posted in another thread, it
> seems your main issue is with "non-glassheads" coming onto your beloved
> hobby group RAT with their anti valve (sorry tube) views. Why then do you
> not make your responses on that group only? Why do you feel the need to
> spread your contributions across other groups too (especially UKRA)?
>
> Roy.

My dear Mr Roy,

I am always happy to explain my actions and words, but the words you
quote were not spoken by me but by the longtime Ukrainian Iain
Churches.

Here is my full post, with my own words (and those of Iain and Patrick
Turners as well), and the explanation you seek below that:

*****Iain Churches wrote:
> "Patrick Turner" > wrote in message
> ...

> > Iain Churches wrote:

> >> So, a thread from Trevor, on the subject of NFB and stability
> >> would be of interest to many I think.

> > I doubt if Trevor could do any better than feign interest in any tube
> > discussion.
> > We all know he is insincere though.

> Let's see if he starts the NFB thread.

Wilson won't. There's a pattern here. Pinkerton, offered an opportunity

to design a tube amp to prove he knows more than we do, refused on the
ground that it would be "nitpicked to death". Wilson obviously has all
the time in the world to write thousands of words about my articles, to

iterate his silly demands that Patrick or I write about the intricacies

of NFB yet again. But when he is invited to contribute an article on
NFB, he claims's he's too busy. Pearce, Krueger, all the other flame
merchants, contribute nothing in their soundbites. Apparently they want

to nitpick everyone else to death but cannot bear exposing themselves
to criticism. They're probably right. If they ever tried to do what
Patrick Turner and John Byrns and you and I do daily, namely actually
explain things, we would soon discover how much they know. They clearly

fear that we will discover they know very little.

> I am a little mystified by the people who spend time on this forum
> and yet have no interest whatsoever, and nothing to contribute on
> the subject of tube audio. Why do they bother?

It's an easy thing to explain for anyone who grew up in a small town.
Wilson, Pinkerton, Krueger, Pearce, and assorted hangers-on like
McKelvy, Wieck, etc, are dried up old maids. twitching their net
curtains, peering out at people having fun, pursing their sour little
mouths and calling the vicar to stop the parade. Their preference of
silicon is dead -- or they believe it is -- with nothing left to decide

except whether Bose or Apple will inherit the remains. There is no
interest left in silicon -- and can you actually believe that such arid

people ever really loved music? -- so our glee in our tubes is doubly
offensive to them, a condition aggravated by the malice ingrained in
their petty, spiteful personalities.

In short, this scum is hounding us for the same reason that school
bullies take the marbles from smaller boys: not because they really
want the marbles but for the sick satisfaction of denying someone else
pleasure. I would bet a year of Pinkerton's salary that every one of
them pulled the wings from butterflies when they were boys.

*******
So, now to answer your question:

The reason I post this to UKRA as well is that the silicon slime came
from UKRA about eighteen months ago with the good wishes of the rest of
the clowns on UKRA -- and with the express purpose of maliciously
wrecking a major project on which RAT was then embarked. I warned UKRA
then that there would be a price to pay; they sneered and jeered, of
course. I don't hear them sneering and jeering any more; before I
finish they will despise Pinkerton, Pearce and the rest of that clutch
of clowns as we on RAT do. I guarantee it.

In short, dear Mr Roy, the scum invaded my patch -- rather
ineffectually, admittedly, but their lack of success is irrelevant when
their impertinence stands on the record -- so now I'm showing them how
it is done by someone competent.

If you're squeamish, you might wish to take a sabbatical until the
Silicon Slime cuts and runs, as eventually they will, though I bet they
are obdurate enough to stay long enough for me to do a permanent job on
their reputations.

Andre Jute
When I stop smiling there is always blood on the carpet. Funny thing:
it is never mine.

[Stewart Pinkerton]

On 29 Mar 2006 01:51:43 -0800, "Andre Jute" > wrote:

>Iain Churches wrote:

>> I am a little mystified by the people who spend time on this forum
>> and yet have no interest whatsoever, and nothing to contribute on
>> the subject of tube audio. Why do they bother?
>
>It's an easy thing to explain for anyone who grew up in a small town.

Asitappens, I did. That's why I easily recognise clumsy Voortrekkers
like you.

>Wilson, Pinkerton, Krueger, Pearce, and assorted hangers-on like
>McKelvy, Wieck, etc, are dried up old maids. twitching their net
>curtains, peering out at people having fun, pursing their sour little
>mouths and calling the vicar to stop the parade.

Actually, I have lots of fun. Much of it comes from reading your
bull****.

> Their preference of
>silicon is dead -- or they believe it is -- with nothing left to decide
>except whether Bose or Apple will inherit the remains.

Apple just might be in a bit of trouble there.......

> There is no
>interest left in silicon -- and can you actually believe that such arid
>people ever really loved music? -- so our glee in our tubes is doubly
>offensive to them, a condition aggravated by the malice ingrained in
>their petty, spiteful personalities.

It's fun to watch people gleefully building crap........

BTW, there's *loads* of interest in silicon, which is why tubes
account for less than 0.1% of the hi-fi market - and no, that's *not*
the top 0.1%................

>In short, this scum is hounding us for the same reason that school
>bullies take the marbles from smaller boys: not because they really
>want the marbles but for the sick satisfaction of denying someone else
>pleasure. I would bet a year of Pinkerton's salary that every one of
>them pulled the wings from butterflies when they were boys.

Not me - but then, unlike you, I never boasted of having people shot
at dawn, either.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

[Ruud Broens]

"Stewart Pinkerton" > wrote in message
...
: On Wed, 29 Mar 2006 15:32:14 +0200, "Ruud Broens" >
: wrote:
: >: >
: >: >hm, about 12 W / 8 Ohm available, > 7 % THD, 88 W idle with the 2SA1216
: >: >and CCS - you're saying there are no tubes that can beat that ?
: >:
: >: I read less than that into those curves, but even if true, that's
: >: better than you'll get with the 300B.
: >:
: >: You are of course conveniently forgetting something else, the greatly
: >: superior gain of the 2SA216. In the KISASS design, Tr2, the equivalent
: >: of the 300B in KISS, has its emitter and collector loads set for a
: >: stage gain of 6.25, to make it as similar as possible to the KISS amp.
: >: This applies more than 20dB of local regeneration, equivalent to the
: >: internal feedback of the 300B, cutting the distortion to about 0.5%.
: >: Apples to apples, KISASS totally outperforms KISS.
: >:
: >: --
: >:
: >: Stewart Pinkerton | Music is Art - Audio is Engineering
: >
: >not forgetting anything here, just sticking with the topic - again -
: >being inherent device linearity, not what you can do with fb - remember ?
:
: Yes, but PT already conceded that the 300B has internal feedback, so
: he had no problem with local degeneration in KISASS. After all,
: putting in a larger emitter resistor doesn't create any of the
: supposed horrors of loop feedback. Note also that you already conceded
: that it's as good or better than a 300B, without *any* feedback.
:
: ...40V supply, - 15 % efficiency and a large 1K/W heatsink for
: >that 2SA1216 and say an LM350.
:
: See KISASS, if you can't remember the basic parameters of KISS.
: KISASS runs a 30 volt rail at the voltage amplifier, and is designed
: to run 100 mA idle current in the voltage amplifier stage.
:
err, wasn't remembering, just exemplifying what it takes.

: >you are also conveniently forgetting that - as is -, you have an input
: >impedance of about 5 Ohms ...
:
: See KISASS for the solution. Tubes use lotsa volts, BJTs use lotsa
: milliamps, same thing in the end for the 'black box' solution.

aha, now we're getting somewhere :-)
so if someone now comes up with an SE pentode output stage, so no fb,
that can do 12W out at <7 % THD, < 88W dissipation,
you'll agree that even the 2SA1216 can be beaten ?
ok ;-)

(btw triodes don't have build-in feedback, more precisely,
they have a build-in feedback facilitating mechanism - as is
evident when you lock the anode voltage; no ~fb~ then)

Rudy

: >more of a win some - loose some scenario, it seems,
: >Stewart ;-)
:
: Not really, as KISS suffers similar problems. Naturally, one wouldn't
: expect a tubie to acknowledge this.
:
: -- -- --
: To reiterate the design process:
:
: KISASS came about as a suggestion by Iain Churches that I design a SS
: equivalent of Andre Jute's (so far mythical) KISS design, supposedly a
: single-ended tube amp with 300B output tube, a double-triode
: input/driver stage, zero loop feedback, and an output of less than ten
: watts. Ignoring a bunch of tube-centric 'rules' spouted by Patrick
: Turner, I had a think about how this should be done.
:
: In terms of parts count, we cannot beat the Nelson Pass ZEN design,
: which uses a single MOSFET, so we will use BJTs, the 'bete noir' of
: the tube fan. In terms of excellent performance from a minimal parts
: count, we have the classic 1969 Linsley Hood design, which ticks most
: of the boxes but does use global NFB.
:
: Where to go from here? OK, let's start from the simplest possible gain
: stage, a common-emitter BJT with emitter and collector loads (Tr2 in
: the schematic, the 2SC2922 device is recommended). This will set the
: transfer curve, and hence the sonic signature, of the amplifier. Such
: a stage does of course have a quite low input impedance, so we place a
: simple emitter follower buffer (Tr1, the MJE15028 will do, or any
: other decent medium power NPN BJT) ahead of it to allow a wider choice
: of source devices. The output impedance (as with the 300B) is much too
: high to drive a loudspeaker, so we need an impedance transformer. As
: one of the great advances of SS was that it allowed the removal of the
: OPT, we will not use iron. A simple pair of emitter followers (Tr3 and
: Tr4, for which the 2SC2922 and 2SA1216 will work well, but other
: modern complementary pairs may substitute) provide output impedance
: reduction without affecting voltage gain, and there we have the design
: in a nutshell.
:
: Further philosophical decisions were the avoidance of bootstrapping
: from the output to the gain stage (that could be construed as loop
: feedback), and the use of a heavily filtered power supply to keep the
: noise floor clean. The latter was in the cause of maintaining the
: 'first watt is the most important' philosophy, without which this
: design is utterly pointless. R15 and R16 reduce the rail voltage to
: give a maximum output power of less than ten watts into loads between
: 8 and 4 ohms, meeting one of the principal design parameters, while
: R12, R13 and R14 maintain the rail voltage of the gain stage at 5
: volts higher than the output rail, allowing better driving of the
: output while maintaining the natural transfer function of the gain
: stage.
:
: The bias current of the output stage is set to about 1 amp by R6,
: while the quiescent output voltage point is set primarily by R1/R2.
: This amplifier should be d.c. and thermally stable, but will reward
: careful layout, particularly in the utilisation of the 'star earth'
: philosophy, i.e. one central ground point to which all 'zero volt'
: connections are made. Given this, I'd expect less than 0.1% THD plus
: noise right across the audio band at an output of 1 watt into 4-8
: ohms, rising to several per cent just below clipping, in the usual
: 'SET' style. The output impedance will also be in the half-ohm region
: over most of the audio band.
:
: In terms of construction, it should be noted that R15 and R16
: dissipate 5 watts each, so should be at least ten-watt rated, while R5
: dissipates about 3 watts, and should be at least a 5-watt component.
: R12, R13 and R14 should be 2-watt rated, the others should be
: half-watt metal films. Note that for thermal stability, D1, D2, Tr3
: and Tr4 must share the same heatsink.
:
: Stewart Pinkerton | Music is Art - Audio is Engineering

[Stewart Pinkerton]

On 28 Mar 2006 23:53:14 -0800, "Andre Jute" > wrote:

>
>Ruud Broens wrote:
>
>> "Stewart Pinkerton" > wrote in message
>> ...
>> : On Tue, 28 Mar 2006 08:59:43 GMT, Patrick Turner
>> : > wrote:
>> :
>> : >
>> : >
>> : >Arny Krueger wrote:
>> : >
>> : >> "Patrick Turner" > wrote in message
>> : >>
>> : >>
>> : >> > They are only as linear as a triode with regard to
>> : >> > voltage gain when external loops of NFB have been applied,
>> : >> > as in the case of the emitter follower connection or
>> : >> > having a few BJTs with a loop of NFB around the
>> : >> > lot of them to correct all their mistakes.
>> : >>
>> : >> > BJTs are inherently non linear for voltage gain and MUST
>> : >> > rely on large amounts of externally connected loops of
>> : >> > NFB.
>> : >>
>> : >> Simply not true. Local feedback works well with BJTs.
>> : >
>> : >Local loops are externally applied loops of NFB.
>> : >
>> : >Bjts are so damned non linear with regard to voltage gain that large amount of
>> : >NFB, local or otherwises must be applied
>> : >to linearize the outcome, as well as raise input impedance.
>> :
>> : Some BJTs are more linear than say a 300B. Why do you keep ignoring
>> : this *fact*. Heresy?
>> :
>> : >It isn't ludicous to drag people screaming back to the basics.
>> : >The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR OTHERWISE applied
>> anywhere
>> : >have hopelessly poor
>> : >voltage gain linearity.
>> :
>> : Utter bunk, check the spec sheet for the 2SA1216. Gain linearity is
>> : flat as a pancake at elevated junction temperatures, as would be
>> : experienced in a Class A amplifier.
>>
>>
>> yep, checking, i found it here:
>> http://users.otenet.gr/~athsam/database.htm
>>
>> the third graph shows Vbe - Ic, the _run hot_ curve
>> does 0.8 V Vbe @ 6 A, 400 mVtt giving 6 Att with 1.6 % distortion
>> certainly impressive. but, now realize the curves are taken at a
>> constant Vce=4V - not very realistic, is it ?
>>
>> now, Hfe about 100, at this 24W class A idle point,
>> 60 mA of base current is required. oops, at 10 A, Hfe has
>> gone south to only 60, creating an additional few dozens
>> of THD %.
>>
>> 2nd take:
>> 0.6Vbe, 2.2 A idle now Hfe stays flat with 200 mVtt in, 4Att out,
>> distortion is 7 % or so that's indeed quite an achievement
>>
>> but considering it's taken at constant Vce
>> reality will be worse
>>
>> : >Statements have been made on the group that what i am saying is untrue.
>> :
>> : That's because it is - see above.
>>
>> hm, about 12 W / 8 Ohm available, > 7 % THD, 8.8 W idle with the 2SA1216
>> you're saying there are no tubes that can beat that ?
>> hmmm
>>
>> the truth,
>> Rudy
>
>Sheesh, Rudy, this BJT the silicon clowns want to flog you isn't much
>chop; in fact it appears to be just a "modern" device number assigned
>to the same old silicon excrement I rejected forty years ago.

Thanks for once again demonstrating your ignorance of electronics.

> A modern
>300B amp, designed with high voltage, high current and high bias in the
>modern Jute style has *less* distortion at full power, and practically
>no 3rd harmonic distortion.

Rudy has his numbers mixed up, especially once you figure local
degeneration into the equation, to match stage gains.

> I show the results of a challenge to me by
>another incompetent pair of idiots. "BobC" Chernofsky and Michael
>LeFevre of Magnequest Transformers. Note that even an incompetently
>designed 300B such as the Bubbaland 300Bis still a more attractive
>(lower odd harmonics) amplifying device than the sliver of silicon ****
>this street-seller of crisped porkfat is trying to palm off on you.
>
>
>Table reads right in Courier 10 pt.
>
>Bob C's "Bubbaland" Andre's "Hedonist"
>
>Grid Plate Grid Plate
>Voltage Current (mA) Voltage Current (mA)
>0.0 102 0.0 136
>-22.3 87 -23.4 119
>-76.0 50 -80.0 80
> -129.7 18 -136.6 44
>-152.0 6 -160.0 30
>
>Load Resistance 5,000 Load Resistance 5,000
>Supply Voltage 350 Supply Voltage 390
>Plate Dissipation 17.5 Plate Dissipation 31.2
>Power Output 5.9 Power Output 7.0
>% 2nd Harmonic 4.13 % 2nd Harmonic 2.83
>% 3rd Harmonic 0.82 % 3rd Harmonic 0.03
>
>(Table courtesy of John Byrns)
>
>******
>Of course, while a silicon amp might be designed to use with
>incompently insensitive speakers and will thus *require* all its power,
>a tube amp like those above (including the now apparently--by
>comparison to the silicon PinkoStinko is trying to flog--not quite so
>incompetent Chernofsky/LeFevre noise generator), is created as part of
>a chain designed back from highly sensitive speakers (both the above
>amps were designed for use with Lowther horns).

Shame that those speakers sound like **** on anything with an extended
frequency range................

>Thus the normal mode of
>the transistor might be flat out while the 300B will idle on
>milliwatts, with vanishing distortion; that is why this class of tube
>amp is normally specified at the 1W it will never in normal working
>see, and the transistor device at full chat.

Actually, the modern SS amp will happily deliver 500 watts of power at
less than 0.1% THD, and distortion at low levels vanishes well beneath
the (lower than that of a SET) noise floor. Shame that your flea-power
SETs are not capable of driving proper loudspeakers with a genuinely
flat response across the entire audio band.

Please also note that most top-class modern speakers are around
90dB/W/m, a mere 10dB below Jute's beloved Lowthers, so the power
required is only ten times greater. Puts those flea-powered SETs which
are utterly incompetent above 5 watts into perspective....

Especially since the first watt of a decent SS amp is still cleaner
than the first watt of a SET.

>Doesn't seem to be anything left to say, does there? (Unless one wants
>to gloat, and we'd never do that, would we?)

Well, you couldn't, could you? :-)

>Hell, our legislators managed to criminalize fox hunting and smoking; I
>wonder when they will get off their collective fat arse and criminalize
>negative feedback. It is clearly consumed only by undesirables.

Since you are clearly the most deranged sociopath to stalk the audio
newsgroups since the late unlamented Alan Derrida, you're hardly in a
position to judge such matters.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

[Stewart Pinkerton]

On Wed, 29 Mar 2006 20:27:29 +0200, "Ruud Broens" >
wrote:

>"Stewart Pinkerton" > wrote in message
...
>: On Wed, 29 Mar 2006 15:32:14 +0200, "Ruud Broens" >
>: wrote:

>: >you are also conveniently forgetting that - as is -, you have an input
>: >impedance of about 5 Ohms ...
>:
>: See KISASS for the solution. Tubes use lotsa volts, BJTs use lotsa
>: milliamps, same thing in the end for the 'black box' solution.
>
>aha, now we're getting somewhere :-)
>so if someone now comes up with an SE pentode output stage, so no fb,
>that can do 12W out at <7 % THD, < 88W dissipation,
>you'll agree that even the 2SA1216 can be beaten ?
> ok ;-)

That'd be fine, as it would even more convincingly (for a tubie)
demonstrate that triodes (and especially DHTs) just aren't what you
want to use in a genuinely top-quality amplifier. Of course, you still
come back to the basic that in a 'black box' with equal voltage gain,
the BJT will win.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

Posted Via Usenet.com Premium Usenet Newsgroup Services
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[Ruud Broens]

"Stewart Pinkerton" > wrote in message
...
: On Wed, 29 Mar 2006 20:27:29 +0200, "Ruud Broens" >
: wrote:
:
: >"Stewart Pinkerton" > wrote in message
: ...
: >: On Wed, 29 Mar 2006 15:32:14 +0200, "Ruud Broens" >
: >: wrote:
:
: >: >you are also conveniently forgetting that - as is -, you have an input
: >: >impedance of about 5 Ohms ...
: >:
: >: See KISASS for the solution. Tubes use lotsa volts, BJTs use lotsa
: >: milliamps, same thing in the end for the 'black box' solution.
: >
: >aha, now we're getting somewhere :-)
: >so if someone now comes up with an SE pentode output stage, so no fb,
: >that can do 12W out at <7 % THD, < 88W dissipation,
: >you'll agree that even the 2SA1216 can be beaten ?
: > ok ;-)
:
: That'd be fine, as it would even more convincingly (for a tubie)
: demonstrate that triodes (and especially DHTs) just aren't what you
: want to use in a genuinely top-quality amplifier. Of course, you still
: come back to the basic that in a 'black box' with equal voltage gain,
: the BJT will win.
:
: --
:
: Stewart Pinkerton | Music is Art - Audio is Engineering

i think you'll find the combination
[ SS ]- Tube - SS, hybrid in that order
from input to output will deliver the highest
gain/distortion ratio,

which is what we want
no use having 10 times the gain comparing X with Y
when Y has 13 times more distortion,
is there ?

if distortion is your game
clean gain is the name,
:-)
Rudy

[Patrick Turner]

Below Pinkerton bull****s to everyone about how to make a simple SS amp.

He did it last year too.

He's repeating the same mistake.

He didn't make or test the amp he tried to foist onto us. Nobody here afaik tried to
build what he suggested;
we wouldn't, since we prefer tubes.

I even said he could use 12dB of NFB because that is how much is in a 300B by my
estimate.
He didn't even check that out of course because he has not the slightest idea how to
establish how much NFB there is in any triode.

But his SS design used a huge total amount of NFB. But he can't cheat while I'm
around.

How come Stewart Oinkerton, the class A pork seller can't build a simple amp?

Nelson Pass beat Oinkerton in this race of course.

Sue Parker also has beaten him.

Patrick Turner.



Stewart Pinkerton wrote:

> On Wed, 29 Mar 2006 15:32:14 +0200, "Ruud Broens" >
> wrote:
>
> >
> >"Stewart Pinkerton" > wrote in message
> ...
> >: On Tue, 28 Mar 2006 23:07:46 +0200, "Ruud Broens" >
> >: wrote:
> >:
> >: >
> >: >: >Bjts are so damned non linear with regard to voltage gain that large amount
> >of
> >: >: >NFB, local or otherwises must be applied
> >: >: >to linearize the outcome, as well as raise input impedance.
> >: >:
> >: >: Some BJTs are more linear than say a 300B. Why do you keep ignoring
> >: >: this *fact*. Heresy?
> >: >:
> >: >: >It isn't ludicous to drag people screaming back to the basics.
> >: >: >The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR OTHERWISE applied
> >: >anywhere
> >: >: >have hopelessly poor
> >: >: >voltage gain linearity.
> >: >:
> >: >: Utter bunk, check the spec sheet for the 2SA1216. Gain linearity is
> >: >: flat as a pancake at elevated junction temperatures, as would be
> >: >: experienced in a Class A amplifier.
> >: >
> >: >
> >: >yep, checking, i found it here:
> >: >http://users.otenet.gr/~athsam/database.htm
> >: >
> >: >the third graph shows Vbe - Ic, the _run hot_ curve
> >: >does 0.8 V Vbe @ 6 A, 400 mVtt giving 8 Att with 1.6 % distortion
> >: > certainly impressive. but, now realize the curves are taken at a
> >: >constant Vce=4V - not very realistic, is it ?
> >: >
> >: >now, Hfe about 100, at this 24W class A idle point,
> >: >60 mA of base current is required. oops, at 10 A, Hfe has
> >: >gone south to only 60, creating an additional few dozens
> >: >of THD %.
> >: >
> >: >2nd take:
> >: >0.6Vbe, 2.2 A idle now Hfe stays flat with 200 mVtt in, 4Att out,
> >: >distortion is 7 % or so that's indeed quite an achievement
> >: >
> >: >but considering it's taken at constant Vce
> >: >reality will be worse
> >: >
> >: >: >Statements have been made on the group that what i am saying is untrue.
> >: >:
> >: >: That's because it is - see above.
> >: >
> >: >hm, about 12 W / 8 Ohm available, > 7 % THD, 8.8 W idle with the 2SA1216
> >: >you're saying there are no tubes that can beat that ?
> >:
> >: I read less than that into those curves, but even if true, that's
> >: better than you'll get with the 300B.
> >:
> >: You are of course conveniently forgetting something else, the greatly
> >: superior gain of the 2SA216. In the KISASS design, Tr2, the equivalent
> >: of the 300B in KISS, has its emitter and collector loads set for a
> >: stage gain of 6.25, to make it as similar as possible to the KISS amp.
> >: This applies more than 20dB of local regeneration, equivalent to the
> >: internal feedback of the 300B, cutting the distortion to about 0.5%.
> >: Apples to apples, KISASS totally outperforms KISS.
> >:
> >: --
> >:
> >: Stewart Pinkerton | Music is Art - Audio is Engineering
> >
> >not forgetting anything here, just sticking with the topic - again -
> >being inherent device linearity, not what you can do with fb - remember ?
>
> Yes, but PT already conceded that the 300B has internal feedback, so
> he had no problem with local degeneration in KISASS. After all,
> putting in a larger emitter resistor doesn't create any of the
> supposed horrors of loop feedback. Note also that you already conceded
> that it's as good or better than a 300B, without *any* feedback.
>
> >it seems you didn't get the impossibility to create 12W out with 8.8 W idle
> >class A, the '-4V Vce from the graph' * 2.2 A idle.
>
> Sure I got it, but obviously KISASS doesn't use a 4 volt rail.....
>
> >to make it work for an 8 Ohm, 12 W output, you'll actually need about
> >40V supply voltage and a current sink pulling 2.2A, together using 88W
> >to get that 12W out - 15 % efficiency and a large 1K/W heatsink for
> >that 2SA1216 and say an LM350.
>
> See KISASS, if you can't remember the basic parameters of KISS.
> KISASS runs a 30 volt rail at the voltage amplifier, and is designed
> to run 100 mA idle current in the voltage amplifier stage.
>
> To reiterate the design process:
>
> KISASS came about as a suggestion by Iain Churches that I design a SS
> equivalent of Andre Jute's (so far mythical) KISS design, supposedly a
> single-ended tube amp with 300B output tube, a double-triode
> input/driver stage, zero loop feedback, and an output of less than ten
> watts. Ignoring a bunch of tube-centric 'rules' spouted by Patrick
> Turner, I had a think about how this should be done.
>
> In terms of parts count, we cannot beat the Nelson Pass ZEN design,
> which uses a single MOSFET, so we will use BJTs, the 'bete noir' of
> the tube fan. In terms of excellent performance from a minimal parts
> count, we have the classic 1969 Linsley Hood design, which ticks most
> of the boxes but does use global NFB.
>
> Where to go from here? OK, let's start from the simplest possible gain
> stage, a common-emitter BJT with emitter and collector loads (Tr2 in
> the schematic, the 2SC2922 device is recommended). This will set the
> transfer curve, and hence the sonic signature, of the amplifier. Such
> a stage does of course have a quite low input impedance, so we place a
> simple emitter follower buffer (Tr1, the MJE15028 will do, or any
> other decent medium power NPN BJT) ahead of it to allow a wider choice
> of source devices. The output impedance (as with the 300B) is much too
> high to drive a loudspeaker, so we need an impedance transformer. As
> one of the great advances of SS was that it allowed the removal of the
> OPT, we will not use iron. A simple pair of emitter followers (Tr3 and
> Tr4, for which the 2SC2922 and 2SA1216 will work well, but other
> modern complementary pairs may substitute) provide output impedance
> reduction without affecting voltage gain, and there we have the design
> in a nutshell.
>
> Further philosophical decisions were the avoidance of bootstrapping
> from the output to the gain stage (that could be construed as loop
> feedback), and the use of a heavily filtered power supply to keep the
> noise floor clean. The latter was in the cause of maintaining the
> 'first watt is the most important' philosophy, without which this
> design is utterly pointless. R15 and R16 reduce the rail voltage to
> give a maximum output power of less than ten watts into loads between
> 8 and 4 ohms, meeting one of the principal design parameters, while
> R12, R13 and R14 maintain the rail voltage of the gain stage at 5
> volts higher than the output rail, allowing better driving of the
> output while maintaining the natural transfer function of the gain
> stage.
>
> The bias current of the output stage is set to about 1 amp by R6,
> while the quiescent output voltage point is set primarily by R1/R2.
> This amplifier should be d.c. and thermally stable, but will reward
> careful layout, particularly in the utilisation of the 'star earth'
> philosophy, i.e. one central ground point to which all 'zero volt'
> connections are made. Given this, I'd expect less than 0.1% THD plus
> noise right across the audio band at an output of 1 watt into 4-8
> ohms, rising to several per cent just below clipping, in the usual
> 'SET' style. The output impedance will also be in the half-ohm region
> over most of the audio band.
>
> In terms of construction, it should be noted that R15 and R16
> dissipate 5 watts each, so should be at least ten-watt rated, while R5
> dissipates about 3 watts, and should be at least a 5-watt component.
> R12, R13 and R14 should be 2-watt rated, the others should be
> half-watt metal films. Note that for thermal stability, D1, D2, Tr3
> and Tr4 must share the same heatsink.
>
> >you are also conveniently forgetting that - as is -, you have an input
> >impedance of about 5 Ohms ...
>
> See KISASS for the solution. Tubes use lotsa volts, BJTs use lotsa
> milliamps, same thing in the end for the 'black box' solution.
>
> >more of a win some - loose some scenario, it seems,
> >Stewart ;-)
>
> Not really, as KISS suffers similar problems. Naturally, one wouldn't
> expect a tubie to acknowledge this.
>
> T reiterate
> --
>
> Stewart Pinkerton | Music is Art - Audio is Engineering

[Andre Jute]

Patrick Turner wrote:
> Below Pinkerton bull****s to everyone about how to make a simple SS amp.
>
> He did it last year too.
>
> He's repeating the same mistake.
>
> He didn't make or test the amp he tried to foist onto us. Nobody here afaik tried to
> build what he suggested;
> we wouldn't, since we prefer tubes.
>
> I even said he could use 12dB of NFB because that is how much is in a 300B by my
> estimate.
> He didn't even check that out of course because he has not the slightest idea how to
> establish how much NFB there is in any triode.
>
> But his SS design used a huge total amount of NFB. But he can't cheat while I'm
> around.
>
> How come Stewart Oinkerton, the class A pork seller can't build a simple amp?

More class G for gross, I think

> Nelson Pass beat Oinkerton in this race of course.
>
> Sue Parker also has beaten him.
>
> Patrick Turner

I couldn't care less about "beating" Pinkerton. I thought we were here
to exchange information to everyone's mutual benefit. I don't even see
what Pinkerton posts until someone replies and most of the time I just
skip those posts.

Less time spent on useless clowns leaves more time for building amps.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

> Stewart Pinkerton wrote:
>
> > On Wed, 29 Mar 2006 15:32:14 +0200, "Ruud Broens" >
> > wrote:
> >
> > >
> > >"Stewart Pinkerton" > wrote in message
> > ...
> > >: On Tue, 28 Mar 2006 23:07:46 +0200, "Ruud Broens" >
> > >: wrote:
> > >:
> > >: >
> > >: >: >Bjts are so damned non linear with regard to voltage gain that large amount
> > >of
> > >: >: >NFB, local or otherwises must be applied
> > >: >: >to linearize the outcome, as well as raise input impedance.
> > >: >:
> > >: >: Some BJTs are more linear than say a 300B. Why do you keep ignoring
> > >: >: this *fact*. Heresy?
> > >: >:
> > >: >: >It isn't ludicous to drag people screaming back to the basics.
> > >: >: >The basic fact is that bjts WITHOUT ANY NFB, LOCAL OR OTHERWISE applied
> > >: >anywhere
> > >: >: >have hopelessly poor
> > >: >: >voltage gain linearity.
> > >: >:
> > >: >: Utter bunk, check the spec sheet for the 2SA1216. Gain linearity is
> > >: >: flat as a pancake at elevated junction temperatures, as would be
> > >: >: experienced in a Class A amplifier.
> > >: >
> > >: >
> > >: >yep, checking, i found it here:
> > >: >http://users.otenet.gr/~athsam/database.htm
> > >: >
> > >: >the third graph shows Vbe - Ic, the _run hot_ curve
> > >: >does 0.8 V Vbe @ 6 A, 400 mVtt giving 8 Att with 1.6 % distortion
> > >: > certainly impressive. but, now realize the curves are taken at a
> > >: >constant Vce=4V - not very realistic, is it ?
> > >: >
> > >: >now, Hfe about 100, at this 24W class A idle point,
> > >: >60 mA of base current is required. oops, at 10 A, Hfe has
> > >: >gone south to only 60, creating an additional few dozens
> > >: >of THD %.
> > >: >
> > >: >2nd take:
> > >: >0.6Vbe, 2.2 A idle now Hfe stays flat with 200 mVtt in, 4Att out,
> > >: >distortion is 7 % or so that's indeed quite an achievement
> > >: >
> > >: >but considering it's taken at constant Vce
> > >: >reality will be worse
> > >: >
> > >: >: >Statements have been made on the group that what i am saying is untrue.
> > >: >:
> > >: >: That's because it is - see above.
> > >: >
> > >: >hm, about 12 W / 8 Ohm available, > 7 % THD, 8.8 W idle with the 2SA1216
> > >: >you're saying there are no tubes that can beat that ?
> > >:
> > >: I read less than that into those curves, but even if true, that's
> > >: better than you'll get with the 300B.
> > >:
> > >: You are of course conveniently forgetting something else, the greatly
> > >: superior gain of the 2SA216. In the KISASS design, Tr2, the equivalent
> > >: of the 300B in KISS, has its emitter and collector loads set for a
> > >: stage gain of 6.25, to make it as similar as possible to the KISS amp.
> > >: This applies more than 20dB of local regeneration, equivalent to the
> > >: internal feedback of the 300B, cutting the distortion to about 0.5%.
> > >: Apples to apples, KISASS totally outperforms KISS.
> > >:
> > >: --
> > >:
> > >: Stewart Pinkerton | Music is Art - Audio is Engineering
> > >
> > >not forgetting anything here, just sticking with the topic - again -
> > >being inherent device linearity, not what you can do with fb - remember ?
> >
> > Yes, but PT already conceded that the 300B has internal feedback, so
> > he had no problem with local degeneration in KISASS. After all,
> > putting in a larger emitter resistor doesn't create any of the
> > supposed horrors of loop feedback. Note also that you already conceded
> > that it's as good or better than a 300B, without *any* feedback.
> >
> > >it seems you didn't get the impossibility to create 12W out with 8.8 W idle
> > >class A, the '-4V Vce from the graph' * 2.2 A idle.
> >
> > Sure I got it, but obviously KISASS doesn't use a 4 volt rail.....
> >
> > >to make it work for an 8 Ohm, 12 W output, you'll actually need about
> > >40V supply voltage and a current sink pulling 2.2A, together using 88W
> > >to get that 12W out - 15 % efficiency and a large 1K/W heatsink for
> > >that 2SA1216 and say an LM350.
> >
> > See KISASS, if you can't remember the basic parameters of KISS.
> > KISASS runs a 30 volt rail at the voltage amplifier, and is designed
> > to run 100 mA idle current in the voltage amplifier stage.
> >
> > To reiterate the design process:
> >
> > KISASS came about as a suggestion by Iain Churches that I design a SS
> > equivalent of Andre Jute's (so far mythical) KISS design, supposedly a
> > single-ended tube amp with 300B output tube, a double-triode
> > input/driver stage, zero loop feedback, and an output of less than ten
> > watts. Ignoring a bunch of tube-centric 'rules' spouted by Patrick
> > Turner, I had a think about how this should be done.
> >
> > In terms of parts count, we cannot beat the Nelson Pass ZEN design,
> > which uses a single MOSFET, so we will use BJTs, the 'bete noir' of
> > the tube fan. In terms of excellent performance from a minimal parts
> > count, we have the classic 1969 Linsley Hood design, which ticks most
> > of the boxes but does use global NFB.
> >
> > Where to go from here? OK, let's start from the simplest possible gain
> > stage, a common-emitter BJT with emitter and collector loads (Tr2 in
> > the schematic, the 2SC2922 device is recommended). This will set the
> > transfer curve, and hence the sonic signature, of the amplifier. Such
> > a stage does of course have a quite low input impedance, so we place a
> > simple emitter follower buffer (Tr1, the MJE15028 will do, or any
> > other decent medium power NPN BJT) ahead of it to allow a wider choice
> > of source devices. The output impedance (as with the 300B) is much too
> > high to drive a loudspeaker, so we need an impedance transformer. As
> > one of the great advances of SS was that it allowed the removal of the
> > OPT, we will not use iron. A simple pair of emitter followers (Tr3 and
> > Tr4, for which the 2SC2922 and 2SA1216 will work well, but other
> > modern complementary pairs may substitute) provide output impedance
> > reduction without affecting voltage gain, and there we have the design
> > in a nutshell.
> >
> > Further philosophical decisions were the avoidance of bootstrapping
> > from the output to the gain stage (that could be construed as loop
> > feedback), and the use of a heavily filtered power supply to keep the
> > noise floor clean. The latter was in the cause of maintaining the
> > 'first watt is the most important' philosophy, without which this
> > design is utterly pointless. R15 and R16 reduce the rail voltage to
> > give a maximum output power of less than ten watts into loads between
> > 8 and 4 ohms, meeting one of the principal design parameters, while
> > R12, R13 and R14 maintain the rail voltage of the gain stage at 5
> > volts higher than the output rail, allowing better driving of the
> > output while maintaining the natural transfer function of the gain
> > stage.
> >
> > The bias current of the output stage is set to about 1 amp by R6,
> > while the quiescent output voltage point is set primarily by R1/R2.
> > This amplifier should be d.c. and thermally stable, but will reward
> > careful layout, particularly in the utilisation of the 'star earth'
> > philosophy, i.e. one central ground point to which all 'zero volt'
> > connections are made. Given this, I'd expect less than 0.1% THD plus
> > noise right across the audio band at an output of 1 watt into 4-8
> > ohms, rising to several per cent just below clipping, in the usual
> > 'SET' style. The output impedance will also be in the half-ohm region
> > over most of the audio band.
> >
> > In terms of construction, it should be noted that R15 and R16
> > dissipate 5 watts each, so should be at least ten-watt rated, while R5
> > dissipates about 3 watts, and should be at least a 5-watt component.
> > R12, R13 and R14 should be 2-watt rated, the others should be
> > half-watt metal films. Note that for thermal stability, D1, D2, Tr3
> > and Tr4 must share the same heatsink.
> >
> > >you are also conveniently forgetting that - as is -, you have an input
> > >impedance of about 5 Ohms ...
> >
> > See KISASS for the solution. Tubes use lotsa volts, BJTs use lotsa
> > milliamps, same thing in the end for the 'black box' solution.
> >
> > >more of a win some - loose some scenario, it seems,
> > >Stewart ;-)
> >
> > Not really, as KISS suffers similar problems. Naturally, one wouldn't
> > expect a tubie to acknowledge this.
> >
> > T reiterate
> > --
> >
> > Stewart Pinkerton | Music is Art - Audio is Engineering

[Stewart Pinkerton]

On Thu, 30 Mar 2006 07:54:30 GMT, Patrick Turner
> wrote:

>Below Pinkerton bull****s to everyone about how to make a simple SS amp.
>
>He did it last year too.
>
>He's repeating the same mistake.
>
>He didn't make or test the amp he tried to foist onto us.

'Foisted'? I was *invited* to design KISASS, as you well know.

> Nobody here afaik tried to
>build what he suggested;
>we wouldn't, since we prefer tubes.

For no apparent reason..............

>I even said he could use 12dB of NFB because that is how much is in a 300B by my
>estimate.
>He didn't even check that out of course because he has not the slightest idea how to
>establish how much NFB there is in any triode.

You'd have to build a pentode, and then remove the other grids to get
an exact equivalence. It can be done quite readily in a high vacuum
lab of course, but I don't know if it's actually been done.

> But his SS design used a huge total amount of NFB. But he can't cheat while I'm
>around.

Turneroid, KISASS wasn't designed to cope with your tube-centric
'rules', it was designed to be a superior version of KISS, and it
performs that function well.

It uses emitter followers at input and output as impedance
transformers, otherwise the amount of *local* degeneration used is
quite modest. No cheating involved, as there are no 'rules', and I
don't care how round you get on all those tinnies.

>How come Stewart Oinkerton, the class A pork seller can't build a simple amp?

I already said that I have no interest in building it.

>Nelson Pass beat Oinkerton in this race of course.

As I clearly stated at the outset - but not with a BJT.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

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[Stewart Pinkerton]

On 24 Mar 2006 09:18:27 -0800, "Bret Ludwig" >
wrote:

> The details of transistor amplifiers have changed immensely and the
>devices have improved, but the physics are still the same as when John
>F. Kennedy was holding up operations at Idlewild while pounding on the
>Monroe Doctrine in SAM 26000. Bipolar transistors are still low
>impedance, current controlled, current controlling devices.

Yes, and your point is?

--

Stewart Pinkerton | Music is Art - Audio is Engineering

Posted Via Usenet.com Premium Usenet Newsgroup Services
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[Mike Gilmour]

"Bret Ludwig" > wrote in message
oups.com...
>
> Ruud Broens wrote:
>
> <<snip>>
>
>
>> The opamp is *designed* to use large amounts of linearising
>> : feedback, something that simply isn't an option with the inherently
>> : much lower open-loop gain of tubes.
>
>
> Philbrick and Julie were building perfectly proper op amps with tubes
> as early as 1943, but thanks for playing.
>

Part of my theory training was the K2-W :-)

Mike

[Arny Krueger]

"Mike Gilmour" > wrote in
message
> "Bret Ludwig" > wrote in message
> oups.com...
>>
>> Ruud Broens wrote:
>>
>> <<snip>>
>>
>>
>>> The opamp is *designed* to use large amounts of
>>> linearising
>>>> feedback, something that simply isn't an option with
>>>> the inherently much lower open-loop gain of tubes.
>>
>>
>> Philbrick and Julie were building perfectly proper op
>> amps with tubes as early as 1943, but thanks for playing.

> Part of my theory training was the K2-W :-)

I started out on a EAI TR-48 as an undergraduate:

http://archive.computerhistory.org/resources/text/EAI/EAI.TR20TR48.1964.102646218.pdf

and moved on to the 680 in my senior year and in graduate school:

http://archive.computerhistory.org/resources/text/EAI/EAI.680.1965.102646244.pdf

The digital side of the system was an IBM 1130. We did not use the EAI
interface box, but instead used a third party interface that included a 200
KHz true 16 bit ADC/DAC box with 16-way multiplexors, in and out.

[Mike Gilmour]

"Arny Krueger" > wrote in message
. ..
> "Mike Gilmour" > wrote in
> message
>> "Bret Ludwig" > wrote in message
>> oups.com...
>>>
>>> Ruud Broens wrote:
>>>
>>> <<snip>>
>>>
>>>
>>>> The opamp is *designed* to use large amounts of
>>>> linearising
>>>>> feedback, something that simply isn't an option with
>>>>> the inherently much lower open-loop gain of tubes.
>>>
>>>
>>> Philbrick and Julie were building perfectly proper op
>>> amps with tubes as early as 1943, but thanks for playing.
>
>> Part of my theory training was the K2-W :-)
>
> I started out on a EAI TR-48 as an undergraduate:
>
> http://archive.computerhistory.org/resources/text/EAI/EAI.TR20TR48.1964.102646218.pdf
>
> and moved on to the 680 in my senior year and in graduate school:
>
> http://archive.computerhistory.org/resources/text/EAI/EAI.680.1965.102646244.pdf
>
> The digital side of the system was an IBM 1130. We did not use the EAI
> interface box, but instead used a third party interface that included a
> 200 KHz true 16 bit ADC/DAC box with 16-way multiplexors, in and out.
>

Looks very good for training. In the early days our Uni's and colleges
didn't invest to much in traing equipment, (except if your were at Aberdeen
Uni in the early 60's where their Univac used up most of the remaining valve
stocks ;-). Thats all SS so I assume you started your training later on,
as it mentions VTOL aircraft & nuclear.
My studies at Southampton were before all that, i.e. exclusively valve
based, hence the K2-W 2 valve opamp. I returned later to study SS over a two
year period then at regular intervals courtesy of Shell oil to study the
likes of microprocessors, instrumentation & control, dynamic positioning
etc. & gain my advanced Marine Electronics Cert. at Bristol. Shell then
relabelled me Senior Electronics Officer, stuck more stripes on my uniform
and put in charge of everthing electronic on supertankers and the building
thereof. (Great job). Then came years of more study time as ships
progressed to unmanned enginerooms with all that entailed. My very first
ship still had a reserve spark transmitter installed but of course it could
not be operated then! My last one had twin satcom, anticollision radars,
doppler logs etc. Quite an evolution process.... and I still love valves :-)