Trevor Wilson wrote:
**It's not often I agree with you, Bret, but SE amps are a con-job, foisted
on the gullible, by those with suspect motives. I have asked for an
justification for SE amps, based on the following problems (so far, all I
have received are lies, insults and just plain bull****):

* ALL SE amps suffer from even order harmonic distortion, which is
automatically reduced by using push pull topology. IOW: All things being
approximately equal (same output valves, high quality iron, good power
supply, same bias current, etc) push pull will outperform SE.

* ALL SE amps suffer appallingly bad load tolerance. IOW: A 20 SE amp (at or
near clipping) will deliver 10 Watts @ 4 Ohms, 5 Watts @ 2 Ohms and so on.
Unless the user has an almost resistive load, then severe power problems can
be expected. This problem can be eliminated by using push pull topology.

* SE amps are MUCH less efficient that a similar power PP amp.

* SE amps, generally, exhibit higher levels of noise than PP amps.

* SE amps have a higher damping factor than a similar PP amp. This may lead
to audible frequency response problems, within the audio range.

For anyone doubting these words, I suggest you refer to the relevant
sections of the RDH4. EVERYTHING I have written, above, has been lifted
directly from the pages of that august publication.

But its not about any of that. Its what sounds good to people. Some
people like SE amps, some people like PP, it all depends on the listener.


Adam

"Adam Stouffer" wrote in message
newsTNlf.2299$ew5.2088@trndny04...
Trevor Wilson wrote:
**It's not often I agree with you, Bret, but SE amps are a con-job,
foisted on the gullible, by those with suspect motives. I have asked for
an justification for SE amps, based on the following problems (so far,
all I have received are lies, insults and just plain bull****):

* ALL SE amps suffer from even order harmonic distortion, which is
automatically reduced by using push pull topology. IOW: All things being
approximately equal (same output valves, high quality iron, good power
supply, same bias current, etc) push pull will outperform SE.

* ALL SE amps suffer appallingly bad load tolerance. IOW: A 20 SE amp (at
or near clipping) will deliver 10 Watts @ 4 Ohms, 5 Watts @ 2 Ohms and so
on. Unless the user has an almost resistive load, then severe power
problems can be expected. This problem can be eliminated by using push
pull topology.

* SE amps are MUCH less efficient that a similar power PP amp.

* SE amps, generally, exhibit higher levels of noise than PP amps.

* SE amps have a higher damping factor than a similar PP amp. This may
lead to audible frequency response problems, within the audio range.

For anyone doubting these words, I suggest you refer to the relevant
sections of the RDH4. EVERYTHING I have written, above, has been lifted
directly from the pages of that august publication.

But its not about any of that.

**Oh, yes, it is about that. I take it then, that you agree with everything
I've written?

Its what sounds good to people.

**Personal preference is fine. People are entitled to listen to whatever
they wish. SE promoters need to learn that PP is a far better way of
achieving high fidelity.

Some
people like SE amps, some people like PP, it all depends on the listener.

**No argument from me.


--
Trevor Wilson
www.rageaudio.com.au

On 7 Dec 2005 06:19:31 -0800, "Andre Jute" wrote:

Pooh Bear wrote:

It isn't worth anything. You've already outlived your welcome here.
**** off.

You're going to have to live with it Joot.

A swinging dick, eh? We get wannabe anklenippers here all the time.
Check 'em out where they now live in the shadows, twitching, dashing in
occasionally for another try at a anklenip. The last one was Pinkerton.
He once had a reputation as an engineer, now he's a public buffoon,
whose only life seems to be commenting bitterly on what I do.

Your self-regard betrays you yet again. I spend perhaps 0.27% of my
Usenet time deconstructing your ignorant bull****. You're certainly
not worth any more than that.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

On 7 Dec 2005 04:47:42 -0800, "Andre Jute" wrote:

This is my thread, about feedback in tubes. If you want to witter on
about silicon ****, go do it elsewhere.

You seem unable to understand that you don't own anything on Usenet,
it's a *public* forum. If you want to witter on about silicon ****,
then at least have the intelligence to realise that there's much more
silicon in a 300B than in a dozen 2N3055s.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

On 7 Dec 2005 05:12:22 -0800, "Andre Jute" wrote:

No manners, no netiquette, no grace, no decency, that's Poopie Bear aka
Graham for you. Instead he is a deliberate wrecker. In other words
scum, as we have seen so often on RAT. Ugh.

Yup - as long as you post here, there will be scum on RAT. BTW, your
first sentence is yet another perfect example of projection.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Wed, 07 Dec 2005 18:04:46 GMT, Patrick Turner
wrote:

Is it not the right of anyone to build whatever amplifier they wish?

Yes.

Why do so many ppl tramp around trying to ban any interest in building
triode amps?

I haven't seen anyone do that. What I *have* seen is people pointing
out what a verbose and self-aggrandising fool Jute is, and how wrong
are his arguments for SET amps. His use of the term 'ultrafidelista'
is particularly risible, given how far from fidelity are his designs.

--

Stewart Pinkerton | Music is Art - Audio is Engineering

On Wed, 7 Dec 2005 18:37:59 +0100, "Ruud Broens"
wrote:


"Andre Jute" wrote in message
roups.com...
:
: Poopie Bear, a siliconslime with time on his hands, aka Graham, wrote:
: Andre Jute wrote:
:
: No manners, no netiquette, no grace, no decency,
:
: Go to hell you top-posting troll.
:
: It's obvious you couldn't sustain a reasoned discussion.
:
: All you can think is *toobs is best* and *NFB is bad* and *SETs are the
: only way*.

well, if you think a mantra, closed mindset is abject,
why is it you seem to hold such a mindset, yourself ?
not very consistent, mr Bear ;-)

care to explain about triodes not being particularly linear ?
(note: Pinkerton has tried _that one_, before)

Well, they're *not* when compared with some modern power transistors
which I have mentioned around here. And of course they get what
linearity they do have, from internal NFB......
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Pooh Bear wrote:


I'd like to know if you have any real credentials as an audio designer.

I don't justify myself anywhere, sonny. But, beyond the contempt in
which I hold you, this is a tube hobbyist conference

No it *isn't*

It's a *public* USENET newsgroup ! It is *not* your personal playpen.

Love it or leave it.

I'm as entitled to be here as anyone.

FWIW I'm intruiged by the continuing interest in tube technology that some
*intelligent* ( i.e. not YOU ) persons have shown. I cut my teeth in electronics when
toobs were still king - but losing fast - so I know a hell of a lot about them and
indeed tube theory and practice ( and their deficiencies - hence in part why I
practice SS now ).

The biggest advantage of doing solid state today is it gets you away
from a lot of neurotics, losers, fabulists and general incompetents. If
I were producing a product for mass commercial manufacture I wouldn't
consider tubes at all.

For hobbyists they are what some of us like to play with. Besides, if
a mountebank and all-around fool like Jute can actually get a tube amp
to work, you know it's pretty idiotproof. Assuming of course he ever
actually has.

Adam Stouffer wrote:



But its not about any of that. Its what sounds good to people. Some
people like SE amps, some people like PP, it all depends on the listener.

That is fine. What isn't fine is claiming high fidelity for such
things. They colour the sound in a way which you like. Just like
the speakers and the room and..., but they aren't hi-fi. They
produce levels of distortion which are very, very high by modern
standards. There is no problem with liking that distortion. There
in no problem with not being able to detect that distortion with
ageing ears. There is a problem with claiming it isn't there.

If the originators of the music had wanted that distortion they
would have included it on the source. You choose to add it because
you disagree with the artist. Maybe the Mona Lisa is better with
a moustache, but it isn't faithful to Leonardo's intent. There
is nothing wrong with being Duchamp, but you can't claim it is
Leonardo's work.

Andy


http://www.ibiblio.org/wm/paint/auth...de/joconde.jpg

http://www.artofeurope.com/duchamp/duc3.htm

wrote:

What was the name of thread where the 50db comment was made? What time
frame are you speaking of?

You made the KISS amp with Triodes correct?
If so you used NFB by virtue of those tubes, right?

But why try to score a cheap point just for the sake of it?

What is being discussed is the effect of the overal loop NFB
that is applied around an amp and NOT the NFB within the triode
due to combined electrostatic action of the anode voltage and grid voltage
upon the electron stream.

The loop FB and the internal FB are different animals.

Patrick Turner.



"Andre Jute" wrote in message
oups.com...
Forwarded because I wouldn't want Arny to think I talk about him or his
monkey behind his back. -- AJ

Andre Jute wrote:
If either if you two blustering nincompoop pinheads, Pinkothicko and
Poop Bear aka Graham (1), had been awake and paying attention any time
in the last ten or fifteen years, you would have known that I spent
years explaining to the ultrafidelista that their amplifiers are loaded
with negative feedback. that SRPP is not a constant current device but
in fact a form of cathode follower, that cathode followers are negative
feedback devices, that their beloved DHT sound so good because the
feedback is built in, in short that feedback is a natural concomitant
of audio engineering, as it is of virtually all engineering.

If either of you two mouthfoaming spittle-spraying moldgrowths had been
sober and attentive, you would have discovered that we discussed
internal feedback in a 300B at some length on RAT earlier this year.
But Pinkothicko, in that thread as in others, instead of learning from
his betters, ponced around sneering and jeering, jerking out insults
while the workers and grafters among us determined that the internal FB
in a 300B amounts to possibly as much as 14dB.

My beef isn't with feedback per se--I've clearly thought on it longer
and more deeply than you two have--but with quarterwits like you two
who think the world stopped turning the day they left whatever
tenth-rate school "edjicated" them.

You two impertinent wannabe anklenippers owe me an apology.

Andre Jute

(1) Arny's ignorance is as inexcusable, though at least he doesn't hang
around tube conferences trying to drain the glee from everyone else's
hobby, so he can't be blamed for not knowing that I know quite as much
as he does about feedback, and a damn sight more about double blind
testing. That Arnie drains the glee from silicon hobbyists is of course
no less reprehensible. But in this instance, Arny's ignorance is the
result of a wilful misreading of what I wrote, magnified by his usual
slimily immoral debating technique, which at least is preferable to the
soup of half-forgotten textbook rule of thumb incomprehension in which
the tenth-raters Pinkothicko and Poop Bear aka Graham flounder.

Stewart Pinkerton wrote:
On Wed, 07 Dec 2005 01:09:03 +0000, Pooh Bear
wrote:



Patrick Turner wrote:

Pooh Bear wrote:

Andre Jute wrote:

From the KISS AMP archive at Jute on Amps
http://members.lycos.co.uk/fiultra/
"an unbelievably comprehensive web site" -- Hi-Fi News & Record
Review

Andre Jute explains why an ultrafi tube amplifier has Zero
Negative
Feedback

Andre Jute is clearly a moron.

Graham

Well methinks moron is a very weary word to use about a description
of a simple amplifier technique that is quite valid for those
not wishing to use loop NFB.

Just what would you do if someone told you that you must not
use NFB?

Maybe you'd tell em to get nicked.

OK, fine, but what if you explored the idea?

Can you think around this idea of no loop FB, without
straight away conjuring up ideas about morons?

When you say 'loop NFB' do you mean overall NFB as opposed to local
NFB ?

I actually use considerable local NFB in my own ( transistor ) designs
before
using modest overall NFB to acheive the final result. There are
several reasons
for this. I just prefer the idea of nice linear stages in the signal
path rather
than correcting them 'after the event' so to speak. Also, applying
local NFB
increaes the stage bandwidth and reduces the phase lag of the
individual stages
thus leading to better overall stability considerations.

Without any NFB, the best that can be acheived is the basic linearity
of the
amplifying device and this really isn't very satisfactory ( except to
someone
with cloth ears maybe ).

I simply detest the unthinking 'all NFB is bad' idea that clowns like
Jute seem
to have picked up which is seemingly based on a valid critique of some
bad
practice that was widespread in the 70s. Actually a lot of the problem
back then
was also a lack of decentfast devices - but that's another story.

The truth is that NFB is essential to any high quality audio device.
Those who
want 1930s listening quality are welcome to it.

More to the point, sad old clowns like Jute seem quite unaware that
their beloved SET amps are jampacked full of NFB - it just happens to
be inside the bottles, rather like your own local NFB.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

Stewart Pinkerton wrote:

On Wed, 07 Dec 2005 18:04:46 GMT, Patrick Turner
wrote:

Is it not the right of anyone to build whatever amplifier they wish?

Yes.

Why do so many ppl tramp around trying to ban any interest in building
triode amps?

I haven't seen anyone do that. What I *have* seen is people pointing
out what a verbose and self-aggrandising fool Jute is, and how wrong
are his arguments for SET amps. His use of the term 'ultrafidelista'
is particularly risible, given how far from fidelity are his designs.

Oinkerton, you have not changed.

You have nothing to add to tube craft expertise.

Why try to hang out here?

Its like sneaking into a synagogue, and selling pork to ppl during a
barmitzvah.

Patrick Turner.





--

Stewart Pinkerton | Music is Art - Audio is Engineering

Andy Cowley wrote:

Adam Stouffer wrote:


But its not about any of that. Its what sounds good to people. Some
people like SE amps, some people like PP, it all depends on the listener.

That is fine. What isn't fine is claiming high fidelity for such
things. They colour the sound in a way which you like. Just like
the speakers and the room and..., but they aren't hi-fi.

But consider your logic, you just said speakers colour the sound
and the room does, so neither are hi-fidelity items.
but ppl build rooms and speakers which could be classified as hi-fi items.

If the basic requirements of the music can be enjoyed using gear with less than

0.1% N&D and a flat response, the gear * is * hi-fi by technical definition,
and plenty of SET amps
offer just this to their owners, and any colour they perceive is the colour of
detail life and recorded warmth
of the music, and what they don't like is the apparent colours offered by
SS gear measuring fractionally better.


They
produce levels of distortion which are very, very high by modern
standards. There is no problem with liking that distortion. There
in no problem with not being able to detect that distortion with
ageing ears. There is a problem with claiming it isn't there.

Have you read the texts on the thresholds at which
measured distortions are perceptible?



If the originators of the music had wanted that distortion they
would have included it on the source.

Don't worry, there is a shirtload of added artifacts added by studios,
compression,
de-essing, eq, reverb, all sorts of effects, and digital jitter.


You choose to add it because
you disagree with the artist. Maybe the Mona Lisa is better with
a moustache, but it isn't faithful to Leonardo's intent. There
is nothing wrong with being Duchamp, but you can't claim it is
Leonardo's work.

The trouble with SET amp bashers is that they just have not heard enough really
good sounding
SET amp based systems which cannot be described as ever being below the highest
hi-fi standards.

I have, so I don't care if I lose this argument, the one that is impossible to
win.

Patrick Turner.



Andy

http://www.ibiblio.org/wm/paint/auth...de/joconde.jpg

http://www.artofeurope.com/duchamp/duc3.htm

"Pooh Bear" wrote in message
...


Trevor Wilson wrote:

"Pooh Bear" wrote in message
...


Trevor Wilson wrote:

"Pooh Bear" wrote in message
...


Patrick Turner wrote:

Pooh Bear wrote:

Andre Jute wrote:

From the KISS AMP archive at Jute on Amps
http://members.lycos.co.uk/fiultra/
"an unbelievably comprehensive web site" -- Hi-Fi News & Record
Review

Andre Jute explains why an ultrafi tube amplifier has Zero
Negative
Feedback

Andre Jute is clearly a moron.

Graham

Well methinks moron is a very weary word to use about a description
of a simple amplifier technique that is quite valid for those
not wishing to use loop NFB.

Just what would you do if someone told you that you must not
use NFB?

Maybe you'd tell em to get nicked.

OK, fine, but what if you explored the idea?

Can you think around this idea of no loop FB, without
straight away conjuring up ideas about morons?

When you say 'loop NFB' do you mean overall NFB as opposed to local
NFB
?

I actually use considerable local NFB in my own ( transistor )
designs
before
using modest overall NFB to acheive the final result. There are
several
reasons
for this. I just prefer the idea of nice linear stages in the signal
path
rather
than correcting them 'after the event' so to speak. Also, applying
local
NFB
increaes the stage bandwidth and reduces the phase lag of the
individual
stages
thus leading to better overall stability considerations.

Without any NFB, the best that can be acheived is the basic
linearity
of
the
amplifying device and this really isn't very satisfactory ( except
to
someone
with cloth ears maybe ).

I simply detest the unthinking 'all NFB is bad' idea that clowns
like
Jute
seem
to have picked up which is seemingly based on a valid critique of
some
bad
practice that was widespread in the 70s. Actually a lot of the
problem
back then
was also a lack of decentfast devices - but that's another story.

The truth is that NFB is essential to any high quality audio device.
Those
who
want 1930s listening quality are welcome to it.

**Well, just to be pedantic, that is exactly why triodes are the most
linear
valves available. They have lots of internal NFB to linearise them.

Which the 'NFB denialists' errr. deny. Because they don't see any
feedback
components.

**Yeah, they're a constant source of amusment.


I still wouldn't call a triode esp linear though. Not by today's
standards.

**They're not bad. Not as good as the best modern devices, that's true,
but
still pretty reasonable.

Talking of linearity, are you familiar with the 'compound pair'
arrangement
typically of 1 x npn and 1 x pnp transistor ( but might equally be 1 jfet
and 1
bipolar ) - also sometimes called a 'super transistor' arrangement ?

The 'second device' is arranged to provided 100% local NFB and the
transfer
characteristic is fabulously linear.

Such pairs can be used without overall NFB to easily provide amplification
with
THD in the 0.00x% region. Widely used in high performance preamps like
low-Z
pro-audio mic amplifiers.

It depends entirely on the availablity of 'opposite polarity' types like
npn an
pnp and hence tubes / valves can't be so configured.

**Quite so and I certainly don't have a problem with active loads on any
devices, to enhance linearity. However, that was not my point. As a SOLE
device, Triodes are quite linear. Better than any other valve type and
certainly better than older style transistors.


--
Trevor Wilson
www.rageaudio.com.au

Patrick Turner wrote:

snip
The trouble with SET amp bashers is that they just have not heard enough really
good sounding
SET amp based systems which cannot be described as ever being below the highest
hi-fi standards.

I have, so I don't care if I lose this argument, the one that is impossible to
win.

Or lose, for that matter.

I would never say that a single ended triode amp can never be any
good. I can and will and will continue to say, that the laws of physics
make it difficult, such that almost all the common ones built by
hobbyists or commercial High End manufacturers are woefully deficient.
I have only heard, as I said earlier, one that was not so bad that I
immediately pegged it as dog poop. All of the several others I have
heard were so bad that had they been _given_ to me I would have
dismantled them and demated their OPTs or shot them with my Contender
and a heavy caliber solid core bullet. Actually, come to think of it, I
might give them to a worthy kid wanting to build a simple guitar amp as
a hobby project, but only after painting it orange so as to ruin any
resale value.

Many of the popular SET designs would be suited to gutting and
rebuilding as push-pull amps.

Andy Cowley wrote:
..

If the originators of the music had wanted that distortion they
would have included it on the source. You choose to add it because
you disagree with the artist. Maybe the Mona Lisa is better with
a moustache, but it isn't faithful to Leonardo's intent. There
is nothing wrong with being Duchamp, but you can't claim it is
Leonardo's work.

By the same argument all modern orchestras are twaddle, stuff and
nonsense because they play Baroque and earlier Classical period musics
on modern instruments-even the Cremona violins, priced as they are five
percent for tone and 95% for penis size writ large, are without
exception all modified greatly with spliced and reset necks and new
fingerboards! Sackbuts and serpents are not to be found, and
Boehm-keyed clarinets have replaced the German pattern entirely so wind
players can double on sax and flute more efficiently. And so forth....

Ironically if you want to hear the sound of a violin as Stradivari
would have, you must listen to a modern replica, built as the "great"
ones originally were, and usually one by an amateur maker or a
shopbuilt instrument because all the modern makers are too busy making
modern style ones, and the Baroque violin is a novelty like a Hardanger
fiddle or a hurdy-gurdy.

As an argument against tube amps in general it's risible because most
good tube amps are not a major "coloring agent" in the chain as opposed
to the record chain and the playback speakers. Even some single ended
amps I would strip sumarily for parts are better than many of the best
and most musically engaging recordings we listen to!

"Patrick Turner" wrote in message
...


wrote:

What was the name of thread where the 50db comment was made? What time
frame are you speaking of?

You made the KISS amp with Triodes correct?
If so you used NFB by virtue of those tubes, right?

But why try to score a cheap point just for the sake of it?

What is being discussed is the effect of the overal loop NFB
that is applied around an amp and NOT the NFB within the triode
due to combined electrostatic action of the anode voltage and grid voltage
upon the electron stream.

The loop FB and the internal FB are different animals.

Patrick Turner.

I just wanted to determine what was actually being discussed and if Mr. Jute
was actually aware of the NFB from triodes, since I have seen other tube
lovers who weren't.




"Andre Jute" wrote in message
oups.com...
Forwarded because I wouldn't want Arny to think I talk about him or his
monkey behind his back. -- AJ

Andre Jute wrote:
If either if you two blustering nincompoop pinheads, Pinkothicko and
Poop Bear aka Graham (1), had been awake and paying attention any time
in the last ten or fifteen years, you would have known that I spent
years explaining to the ultrafidelista that their amplifiers are
loaded
with negative feedback. that SRPP is not a constant current device but
in fact a form of cathode follower, that cathode followers are
negative
feedback devices, that their beloved DHT sound so good because the
feedback is built in, in short that feedback is a natural concomitant
of audio engineering, as it is of virtually all engineering.

If either of you two mouthfoaming spittle-spraying moldgrowths had
been
sober and attentive, you would have discovered that we discussed
internal feedback in a 300B at some length on RAT earlier this year.
But Pinkothicko, in that thread as in others, instead of learning from
his betters, ponced around sneering and jeering, jerking out insults
while the workers and grafters among us determined that the internal
FB
in a 300B amounts to possibly as much as 14dB.

My beef isn't with feedback per se--I've clearly thought on it longer
and more deeply than you two have--but with quarterwits like you two
who think the world stopped turning the day they left whatever
tenth-rate school "edjicated" them.

You two impertinent wannabe anklenippers owe me an apology.

Andre Jute

(1) Arny's ignorance is as inexcusable, though at least he doesn't
hang
around tube conferences trying to drain the glee from everyone else's
hobby, so he can't be blamed for not knowing that I know quite as much
as he does about feedback, and a damn sight more about double blind
testing. That Arnie drains the glee from silicon hobbyists is of
course
no less reprehensible. But in this instance, Arny's ignorance is the
result of a wilful misreading of what I wrote, magnified by his usual
slimily immoral debating technique, which at least is preferable to
the
soup of half-forgotten textbook rule of thumb incomprehension in which
the tenth-raters Pinkothicko and Poop Bear aka Graham flounder.

Stewart Pinkerton wrote:
On Wed, 07 Dec 2005 01:09:03 +0000, Pooh Bear
wrote:



Patrick Turner wrote:

Pooh Bear wrote:

Andre Jute wrote:

From the KISS AMP archive at Jute on Amps
http://members.lycos.co.uk/fiultra/
"an unbelievably comprehensive web site" -- Hi-Fi News &
Record
Review

Andre Jute explains why an ultrafi tube amplifier has Zero
Negative
Feedback

Andre Jute is clearly a moron.

Graham

Well methinks moron is a very weary word to use about a
description
of a simple amplifier technique that is quite valid for those
not wishing to use loop NFB.

Just what would you do if someone told you that you must not
use NFB?

Maybe you'd tell em to get nicked.

OK, fine, but what if you explored the idea?

Can you think around this idea of no loop FB, without
straight away conjuring up ideas about morons?

When you say 'loop NFB' do you mean overall NFB as opposed to local
NFB ?

I actually use considerable local NFB in my own ( transistor )
designs
before
using modest overall NFB to acheive the final result. There are
several reasons
for this. I just prefer the idea of nice linear stages in the
signal
path rather
than correcting them 'after the event' so to speak. Also, applying
local NFB
increaes the stage bandwidth and reduces the phase lag of the
individual stages
thus leading to better overall stability considerations.

Without any NFB, the best that can be acheived is the basic
linearity
of the
amplifying device and this really isn't very satisfactory ( except
to
someone
with cloth ears maybe ).

I simply detest the unthinking 'all NFB is bad' idea that clowns
like
Jute seem
to have picked up which is seemingly based on a valid critique of
some
bad
practice that was widespread in the 70s. Actually a lot of the
problem
back then
was also a lack of decentfast devices - but that's another story.

The truth is that NFB is essential to any high quality audio
device.
Those who
want 1930s listening quality are welcome to it.

More to the point, sad old clowns like Jute seem quite unaware that
their beloved SET amps are jampacked full of NFB - it just happens
to
be inside the bottles, rather like your own local NFB.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

"Bret Ludwig" wrote in message
oups.com...
:
: Patrick Turner wrote:
:
: snip
: The trouble with SET amp bashers is that they just have not heard enough
really
: good sounding
: SET amp based systems which cannot be described as ever being below the
highest
: hi-fi standards.
:
: I have, so I don't care if I lose this argument, the one that is impossible
to
: win.
:
: Or lose, for that matter.
:
: I would never say that a single ended triode amp can never be any
: good. I can and will and will continue to say, that the laws of physics
: make it difficult, such that almost all the common ones built by
: hobbyists or commercial High End manufacturers are woefully deficient.
: I have only heard, as I said earlier, one that was not so bad that I
: immediately pegged it as dog poop. All of the several others I have
: heard were so bad that had they been _given_ to me I would have
: dismantled them and demated their OPTs or shot them with my Contender
: and a heavy caliber solid core bullet. Actually, come to think of it, I
: might give them to a worthy kid wanting to build a simple guitar amp as
: a hobby project, but only after painting it orange so as to ruin any
: resale value.
:
: Many of the popular SET designs would be suited to gutting and
: rebuilding as push-pull amps.


let's have a list then:
brand & type listened to with speakers : room description:
measured average and peak power during listening
other listeners present ? their experience ?

maybe then your experience is worth something to others..
at the moment, we might as well conclude you're just a guy
with severe hearing troubles :-)

Rudy

Bret Ludwig wrote:

Patrick Turner wrote:

snip
The trouble with SET amp bashers is that they just have not heard enough really
good sounding
SET amp based systems which cannot be described as ever being below the highest
hi-fi standards.

I have, so I don't care if I lose this argument, the one that is impossible to
win.

Or lose, for that matter.

I would never say that a single ended triode amp can never be any
good. I can and will and will continue to say, that the laws of physics
make it difficult, such that almost all the common ones built by
hobbyists or commercial High End manufacturers are woefully deficient.

The very expensive Ongaku, some of the Cary and bel Canto amps
which use transmit triodes to put out over 20 watts are very nice to listen
with if you are not a head banger, or deliberately turn up the volume well
into clip and then call the amps terrible.

But samples of 8 watt 300B amps made by all sorts of pp, do
better with music than any PP UL amp using a pair of 6BM8.

Certainly better than an 8 watt transistor amp.

Be fair now, let's not compare goosberries to watermelons.




I have only heard, as I said earlier, one that was not so bad that I
immediately pegged it as dog poop. All of the several others I have
heard were so bad that had they been _given_ to me I would have
dismantled them and demated their OPTs or shot them with my Contender
and a heavy caliber solid core bullet. Actually, come to think of it, I
might give them to a worthy kid wanting to build a simple guitar amp as
a hobby project, but only after painting it orange so as to ruin any
resale value.

Many of the popular SET designs would be suited to gutting and
rebuilding as push-pull amps.

The worst SE amp I heard music through had a single EL34 in pentode,
with 12 dB NFB which isn't enough for a pentode, and a 2.5k anode load
with Ea = 450V, which is a very poor load/Ea match. It was a kit amp a guy had bought
from Thailand, and a POS
which sounded worse than the tranny amp it was bought to replace.
Build quality was attrocious.

A 300B would have been so much better.

Patrick Turner.

"Stewart Pinkerton" wrote in message
...
: On Wed, 7 Dec 2005 18:37:59 +0100, "Ruud Broens"
: wrote:
:
:
: "Andre Jute" wrote in message
: roups.com...
: :
: : Poopie Bear, a siliconslime with time on his hands, aka Graham, wrote:
: : Andre Jute wrote:
: :
: : No manners, no netiquette, no grace, no decency,
: :
: : Go to hell you top-posting troll.
: :
: : It's obvious you couldn't sustain a reasoned discussion.
: :
: : All you can think is *toobs is best* and *NFB is bad* and *SETs are the
: : only way*.
:
: well, if you think a mantra, closed mindset is abject,
: why is it you seem to hold such a mindset, yourself ?
: not very consistent, mr Bear ;-)
:
: care to explain about triodes not being particularly linear ?
: (note: Pinkerton has tried _that one_, before)
:
: Well, they're *not* when compared with some modern power transistors
: which I have mentioned around here. And of course they get what
: linearity they do have, from internal NFB......
: --
:
: Stewart Pinkerton | Music is Art - Audio is Engineering
.................................................. ................................
...................

Yeah, yeah, we know about your debating trade techniques, Stewart :-)

About that minimal parts competetive design you halfbaked upon us:
for some constructive continuation, let's give you the hard part,
the V to I conversion, before your I to I transistor amp configuration
-in the context of the minimal parts/feedback design contest, right ?-

What about a hybrid design, V to I done by a tube*, I to I amplification with
the devices you favour, from the MJL family,

I realize Christmas is a bit short notice, say done about Easter 2006 ?

(who knows, maybe even mr. Bear can contribute online
& show his openmindedness

in anticipation,
awaitin',
Rudy

*here's an original suggestion:
use the DH (1.25V/50mA nom.) pencil tube 5672, trioded,
with a 135 V B+ supply, Ra=18K, 3.2 mA idle, -8V bias
(plenty of overload margin with CD output, you will note

power the filament with a CCSource at one end (fil +),
a CCSink at the other (ss, of course) :
that will give you an output of about 0.2 mA/V^, riding on a DC current
of anywhere between negligable and 30 mA or so for the next stage
available at the fil(-) point, to be set at your choice.

tweakers delight: lowering the Ra will increase 2H,
lowering the filament current changes the tubes working conditions,
changing the difference between source and sink will do so for the
transistor following, giving all sorts of possible cancellation or
increased distortion at will, depending on the intended use
or listeners preference ;-)
* * *
^ i hope we won't get the "a 5K resistor will do that better"
type of remarks, the 5672 grid resistor can be 150K for a
normal input impedance, eh ?

Nyobe Queen of Ignorance wrote: "Patrick Turner"
wrote in message
...

I just wanted to determine what was actually being discussed and if Mr. Jute
was actually aware of the NFB from triodes, since I have seen other tube
lovers who weren't.

You didn't even know enough about me to discover the significant fact
that I have been saying that for years, but you wrote half-a-dozen
vicious attack messages?

If you were a man, Nyobe who wants to be called Mike, you would be a
premature ejaculator.

Andre Jute

"Andre Jute" wrote in message
oups.com...

Nyobe Queen of Ignorance wrote: "Patrick Turner"
wrote in message
...

I just wanted to determine what was actually being discussed and if Mr.
Jute
was actually aware of the NFB from triodes, since I have seen other tube
lovers who weren't.

You didn't even know enough about me to discover the significant fact
that I have been saying that for years, but you wrote half-a-dozen
vicious attack messages?

I did nothing of the sort, I asked some pertinent questions, which you
ducked.


If you were a man, Nyob who wants to be called Mike, you would be a
premature ejaculator.

Andre Jute

Ever build the KISS amp?
Where is it?
Why are you so desperate that you create a sock to defend you who is
instantly caught lying?

You're kinda pathetic when cornered, you instantly start name calling and
crying.

You might be fun to play with for a while, but eventually you'll become
boring.
Probably very soon.
It's funny how much you remind me of our former idiot Dr. B.J. Quackenbush.
Well not funny ha ha, funny strange.

Ruud Broens wrote:
"Stewart Pinkerton" wrote in message
...
: On Wed, 7 Dec 2005 18:37:59 +0100, "Ruud Broens"
: wrote:
: "Andre Jute" wrote in message
: roups.com...
: :
: : Poopie Bear, a siliconslime with time on his hands, aka Graham, wrote:
: : Andre Jute wrote:
: :
: : No manners, no netiquette, no grace, no decency,
: :
: : Go to hell you top-posting troll.
: :
: : It's obvious you couldn't sustain a reasoned discussion.
: :
: : All you can think is *toobs is best* and *NFB is bad* and *SETs are the
: : only way*.
:
: well, if you think a mantra, closed mindset is abject,
: why is it you seem to hold such a mindset, yourself ?
: not very consistent, mr Bear ;-)
:
: care to explain about triodes not being particularly linear ?
: (note: Pinkerton has tried _that one_, before)
:
: Well, they're *not* when compared with some modern power transistors
: which I have mentioned around here. And of course they get what
: linearity they do have, from internal NFB......
: --
:
: Stewart Pinkerton | Music is Art - Audio is Engineering
.................................................. ...............................
..................

Yeah, yeah, we know about your debating trade techniques, Stewart :-)

About that minimal parts competetive design you halfbaked upon us:
for some constructive continuation, let's give you the hard part,
the V to I conversion, before your I to I transistor amp configuration
-in the context of the minimal parts/feedback design contest, right ?-

What about a hybrid design, V to I done by a tube*, I to I amplification with
the devices you favour, from the MJL family,

I realize Christmas is a bit short notice, say done about Easter 2006 ?

(who knows, maybe even mr. Bear can contribute online
& show his openmindedness

in anticipation,
awaitin',
Rudy

Are you just noodling, Rudy, or are you actually innocent enough to
expect constructive input from these two flaming interlopers? I admire
innocence, especially in young women... LOL.

*here's an original suggestion:
use the DH (1.25V/50mA nom.) pencil tube 5672, trioded,
with a 135 V B+ supply, Ra=18K, 3.2 mA idle, -8V bias
(plenty of overload margin with CD output, you will note

power the filament with a CCSource at one end (fil +),
a CCSink at the other (ss, of course) :
that will give you an output of about 0.2 mA/V^, riding on a DC current
of anywhere between negligable and 30 mA or so for the next stage
available at the fil(-) point, to be set at your choice.

tweakers delight: lowering the Ra will increase 2H,
lowering the filament current changes the tubes working conditions,
changing the difference between source and sink will do so for the
transistor following, giving all sorts of possible cancellation or
increased distortion at will, depending on the intended use
or listeners preference ;-)
* * *
^ i hope we won't get the "a 5K resistor will do that better"
type of remarks, the 5672 grid resistor can be 150K for a
normal input impedance, eh ?

For anything that complicated you will have to wait until Easter 2007,
and then put up with months of excuses about why the design is only on
paper.

Andre Jute

"Andre Jute" wrote in message
oups.com...
:
: Are you just noodling, Rudy, or are you actually innocent enough to
: expect constructive input from these two flaming interlopers? I admire
: innocence, especially in young women... LOL.
:
now Andre, dear, let's not discuss my true identity here,
don't wanna give our Bret the wrong ideas..
R.
:
: For anything that complicated you will have to wait until Easter 2007,
: and then put up with months of excuses about why the design is only on
: paper.
:
: Andre Jute
: )

"Andre Jute" wrote in message
oups.com...

Ruud Broens wrote:
"Stewart Pinkerton" wrote in message
...
: On Wed, 7 Dec 2005 18:37:59 +0100, "Ruud Broens"
: wrote:
: "Andre Jute" wrote in message
: roups.com...
: :
: : Poopie Bear, a siliconslime with time on his hands, aka Graham,
wrote:
: : Andre Jute wrote:
: :
: : No manners, no netiquette, no grace, no decency,
: :
: : Go to hell you top-posting troll.
: :
: : It's obvious you couldn't sustain a reasoned discussion.
: :
: : All you can think is *toobs is best* and *NFB is bad* and *SETs
are the
: : only way*.
:
: well, if you think a mantra, closed mindset is abject,
: why is it you seem to hold such a mindset, yourself ?
: not very consistent, mr Bear ;-)
:
: care to explain about triodes not being particularly linear ?
: (note: Pinkerton has tried _that one_, before)
:
: Well, they're *not* when compared with some modern power transistors
: which I have mentioned around here. And of course they get what
: linearity they do have, from internal NFB......
: --
:
: Stewart Pinkerton | Music is Art - Audio is Engineering
.................................................. ...............................
..................

Yeah, yeah, we know about your debating trade techniques, Stewart :-)

About that minimal parts competetive design you halfbaked upon us:
for some constructive continuation, let's give you the hard part,
the V to I conversion, before your I to I transistor amp configuration
-in the context of the minimal parts/feedback design contest, right ?-

What about a hybrid design, V to I done by a tube*, I to I amplification
with
the devices you favour, from the MJL family,

I realize Christmas is a bit short notice, say done about Easter 2006 ?

(who knows, maybe even mr. Bear can contribute online
& show his openmindedness

in anticipation,
awaitin',
Rudy

Are you just noodling, Rudy, or are you actually innocent enough to
expect constructive input from these two flaming interlopers? I admire
innocence, especially in young women... LOL.

*here's an original suggestion:
use the DH (1.25V/50mA nom.) pencil tube 5672, trioded,
with a 135 V B+ supply, Ra=18K, 3.2 mA idle, -8V bias
(plenty of overload margin with CD output, you will note

power the filament with a CCSource at one end (fil +),
a CCSink at the other (ss, of course) :
that will give you an output of about 0.2 mA/V^, riding on a DC current
of anywhere between negligable and 30 mA or so for the next stage
available at the fil(-) point, to be set at your choice.

tweakers delight: lowering the Ra will increase 2H,
lowering the filament current changes the tubes working conditions,
changing the difference between source and sink will do so for the
transistor following, giving all sorts of possible cancellation or
increased distortion at will, depending on the intended use
or listeners preference ;-)
* * *
^ i hope we won't get the "a 5K resistor will do that better"
type of remarks, the 5672 grid resistor can be 150K for a
normal input impedance, eh ?

For anything that complicated you will have to wait until Easter 2007,
and then put up with months of excuses about why the design is only on
paper.

Andre Jute

You mean like the KISSamp you never built?

"Andre Jute" wrote in message
oups.com...

You didn't even know enough about me to discover the significant fact
that I have been saying that for years, but you wrote half-a-dozen
vicious attack messages?

As if the following isn't a vicious attack message! LOL!

If you were a man, Nyobe who wants to be called Mike, you would be a
premature ejaculator.

Andre Jute

"Arny Krueger" wrote in message
news

"Andre Jute" wrote in message
oups.com...

You didn't even know enough about me to discover the significant fact
that I have been saying that for years, but you wrote half-a-dozen
vicious attack messages?

As if the following isn't a vicious attack message! LOL!

If you were a man, Nyobe who wants to be called Mike, you would be a
premature ejaculator.

It's an attack, but I don't know that I would call it all that vicious, any
more than a yapping little dog is vicious.

Most of what Jute spews forth is intended to be nasty, but mostly it just
appears to be weak and like him, ineffectual.

"Patrick Turner" wrote in message
...


Trevor Wilson wrote:

"Bret Ludwig" wrote in message
oups.com...
Zero NFB single ended triode amps are not "ultra-fi": they are "my-fi"
at best and "****-poor-fi" in most cases. They don't sound good! A
Marantz 8B or 5, an early pointwired VTL, or even a refurbed Mac MC40
will sonically beat the hell out of the SET amps I have heard. With no
damping factor to consider they have no cone control, and flap like the
private parts of downwind-headed female bovines.

The best SET amp I have heard was a homemade copy of the 27W "Ongaku".
(It sounded better than the real thing IMO, although i was unable to
conduct a proper comparison to be totally objective.) It was tolerable,
but when an actual Marantz 8B was substituted, the sound from the same
speakers was overall slightly improved. A solid state Mac 754 was the
"control" amp and the Marantz bested both (the Mac wasn't as bad as I
would have thought.)

Most homebrew SETs using WE 300Bs, 2A3's and the like I have heard
were simply not very good whatsoever at the business of reproducing
music. I cannot and will not make any attempt to listen to all SE amps:
I have heard enough, I believe, to say with a straight face that they
mostly stink. VTL/Manley built a 300B amp years ago that could be run
as a PSE or PP amp and that also tended to solidly prove the theory, as
did a homebuilt I heard years ago that similarly used a single 6AS7 and
a Japanese Tango "universal" OPT.

**It's not often I agree with you, Bret, but SE amps are a con-job,
foisted
on the gullible, by those with suspect motives. I have asked for an
justification for SE amps, based on the following problems (so far, all I
have received are lies, insults and just plain bull****):

* ALL SE amps suffer from even order harmonic distortion, which is
automatically reduced by using push pull topology. IOW: All things being
approximately equal (same output valves, high quality iron, good power
supply, same bias current, etc) push pull will outperform SE.

* ALL SE amps suffer appallingly bad load tolerance. IOW: A 20 SE amp (at
or
near clipping) will deliver 10 Watts @ 4 Ohms, 5 Watts @ 2 Ohms and so
on.
Unless the user has an almost resistive load, then severe power problems
can
be expected. This problem can be eliminated by using push pull topology.

* SE amps are MUCH less efficient that a similar power PP amp.

* SE amps, generally, exhibit higher levels of noise than PP amps.

* SE amps have a higher damping factor than a similar PP amp. This may
lead
to audible frequency response problems, within the audio range.

For anyone doubting these words, I suggest you refer to the relevant
sections of the RDH4. EVERYTHING I have written, above, has been lifted
directly from the pages of that august publication.

--
Trevor Wilson
www.rageaudio.com.au

Trevor, you spout abysmally incorrect technical statements about tube
amps.

Go back to aus.hi-fi and stay there.

All you ever achieve at rec.audio.tubes is the gaining of a reputation
for moronic stupidity.

Your archive record on SET amps is a litany of BS.

Get a good pillow for sleeping, you brain is heavy, its mainly stone.

Folks, millions of SE amps were produced and employed as sound amps in
radios and TV sets long before PP amps came into mainstream use.

TW's general interpretation of RDH4 is hopelessly wrong because he fails
to
take into account the finer details.

Trevor has never designed or built ANY amplifier since 1975.

This man knows almost nothing about amplifiers, he just likes being in
discussions,
and using the fancy amplifier jargon.

If Trevor were to build a decent pair of 845 amps be may change his
opinions,
but he won't build anything.

Then he'd complain about the cost and weight of it all.

But nobody listens to the cost and weight......


Patrick Turner.



Lack of technical rebuttal to anything Trevor said is noted.

"Adam Stouffer" wrote in message
newsTNlf.2299$ew5.2088@trndny04...
Trevor Wilson wrote:
**It's not often I agree with you, Bret, but SE amps are a con-job,
foisted on the gullible, by those with suspect motives. I have asked for
an justification for SE amps, based on the following problems (so far,
all I have received are lies, insults and just plain bull****):

* ALL SE amps suffer from even order harmonic distortion, which is
automatically reduced by using push pull topology. IOW: All things being
approximately equal (same output valves, high quality iron, good power
supply, same bias current, etc) push pull will outperform SE.

* ALL SE amps suffer appallingly bad load tolerance. IOW: A 20 SE amp (at
or near clipping) will deliver 10 Watts @ 4 Ohms, 5 Watts @ 2 Ohms and so
on. Unless the user has an almost resistive load, then severe power
problems can be expected. This problem can be eliminated by using push
pull topology.

* SE amps are MUCH less efficient that a similar power PP amp.

* SE amps, generally, exhibit higher levels of noise than PP amps.

* SE amps have a higher damping factor than a similar PP amp. This may
lead to audible frequency response problems, within the audio range.

For anyone doubting these words, I suggest you refer to the relevant
sections of the RDH4. EVERYTHING I have written, above, has been lifted
directly from the pages of that august publication.

But its not about any of that. Its what sounds good to people. Some people
like SE amps, some people like PP, it all depends on the listener.



Then why claim anything about ultra fidelity? Clearly these amps are not
ultra fidelity, they are ultra distoprtion, and ultra noise. If you or
anyone else wants to like the sound of that, nobody will challenge your
right to do so. Claiming they are ultra anythig to do with fidelity is a
challenge for people who know better to tell why that is complete nonsense.

wrote in message
nk.net...

Lack of technical rebuttal to anything Trevor said is noted.

**Of course. Not only does Patrick KNOW that I am correct, but the
information is contained within his primary reference material (The
Radiotron Designer's Handbook).


--
Trevor Wilson
www.rageaudio.com.au

Adam Stouffer wrote:

Trevor Wilson wrote:
**It's not often I agree with you, Bret, but SE amps are a con-job, foisted
on the gullible, by those with suspect motives. I have asked for an
justification for SE amps, based on the following problems (so far, all I
have received are lies, insults and just plain bull****):

* ALL SE amps suffer from even order harmonic distortion, which is
automatically reduced by using push pull topology. IOW: All things being
approximately equal (same output valves, high quality iron, good power
supply, same bias current, etc) push pull will outperform SE.

* ALL SE amps suffer appallingly bad load tolerance. IOW: A 20 SE amp (at or
near clipping) will deliver 10 Watts @ 4 Ohms, 5 Watts @ 2 Ohms and so on.
Unless the user has an almost resistive load, then severe power problems can
be expected. This problem can be eliminated by using push pull topology.

* SE amps are MUCH less efficient that a similar power PP amp.

* SE amps, generally, exhibit higher levels of noise than PP amps.

* SE amps have a higher damping factor than a similar PP amp. This may lead
to audible frequency response problems, within the audio range.

For anyone doubting these words, I suggest you refer to the relevant
sections of the RDH4. EVERYTHING I have written, above, has been lifted
directly from the pages of that august publication.

But its not about any of that. Its what sounds good to people. Some
people like SE amps, some people like PP, it all depends on the listener.

Adam

PPl are welcome to listen to whatever they find to pleasing to their ear. That, as
you say, is what listening pleasure is all about.

The problem with the SET Jihadists however is that they choose to present their
preference as 'superior' when it is readily demonstrable that is actually very
low-fi when compared to other design solutions.

Fidelity meaning the recreation of an accurate replica of the input, as can be
readily measured.

Graham

"Patrick Turner" wrote in message
...


Sander deWaal wrote:

"Andre Jute" said:

Good heavens. I couldn't believe that was his entire argument so I went
back to look up Graham's post. (I normally don't open the posts of the
more useless posters.) I wish you luck, Patrick, in extracting sense
from Poop Bear; if you do, you are better man than me, Gunga Din. Since
you're such saint, maybe you can next work on the other superstar of
the debating society whom I also found -- I quote his entire post:

snip

Just look what Arny had to say to one of your posts about the use of
NFB ....the original was posted to RAO by our friend Brat Ludwig :-)

- begin long quote -

Arny Krueger said:

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.

Good example of Jute's ignorance of the engineering
education process. Feedback is usually taught as it relates
to automatic control systems. Last time I looked courses
like these generally fit into the junior or senior years.

In short the idea that "He learns to say '100dB of NFB in
his sleep before he
finishes his first week at the most humble polytechnic" is
sheerist BS.

Its not BS.

Even I have built plenty of fair sounding SS amps with a total of 100dB
of NFB, and many commercial designs use this much.

First you have the emitter follower output stage and there is 40 dB, and
then there is often 60
dB of global, so there is your 100dB; its very standard practice and i
suggest a good read of Douglas Self's
site to understand it better.
Without any global NFB it only takes about 2mV of input for clipping at
100
watts;
thats typical Linn topology open loop gain in SS amps.



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.

Good example of Jute's ignorance of feedback. It's highly
unlikely that one could apply 50 dB loop feedback to a power
amp with an output transformer and still have acceptable
stability.

But a wannabe suggested Jute use the 50 dB more gain and FB.
Jute was refuting the wannabe's recomendation.

It is almost impossible to apply 50 dB of global FB in any OPT coupled
amp. Jute knows this.



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 amount of rediculous posturing can counter the fact that
NFB can be made to work very well and to great advantage,
thank you.

Yes, agreed, but you still don't have to use global FB if you don't want
to
around triode amps .
Jute may take his time to get to the point, but triodes CAN be used
without
loop FB.
Transistors, mosfets, and pentodes and tetrodes cannot.

Triodes have their own internal electrostatic loops of FB which one cannot
avoid,
but which are the most natural form of FB known and can be best exploited
by
keeping
load values high with respect to Ra.
It is why they are so linear when loaded in a signal voltage amp with a
CCS
load.



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.

If the kiss amp has less than 0.05% nonlinear distortion
with any power level or any frequency or combination of
frequencies 20-20 KHz, then its fine as is. I doubt it is
that good.

Ah, the doubters. If only they could listen to an 845 Bel Canto or some
such
amp......



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.

This is a highly incomplete explanation. In fact the voltage
fed back offsets not only the distortion but a goodly part
of the basic signal. Therefore, NFB generally reduces an
amplifier's gain for both the basic amplfied signal and also
the distortion.


NFB is better explained in the old books, but newbies cannot be expected
to
understand first off
all the mumbo jumbo of old books.
Jute is trying to make ideas of NFB seem understandable.

Almost nobody I meet who is not a tech has the slightest idea of the basic
gain/FB equation,
ie, that
gain with FB = A / ( 1 + [A x ß] )
So how do you introduce ideas about FB?






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.

In fact NFB properly applied reduces, not increases an
amplifier's phase shift.

Indeed this is true.



'Wow!' those meeting NFB for the first time will now say,
'Something for free! I'll grab some of that for my amp.'

Just just contrdicted the first phrase in the previous
paragraph that says that NFB has a price in the form of a
loss of gain.

A misunderstanding.
NFB is a technique that reduces thd/imd/phase shift for nothing, almost.
But you must pay for the greater open loop gain needed.
Simple.





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.

Jute's mistake here is that its not heresy to question
measurements, and people have been doing that for decades,
even in such conservative journals as the JAES.

It is ok to question measurements.
But Jute is on the side of the questioner, he is mocking the
slavish devotion to measurements in so many
engineering minds.
Halcro amps make 0.0001% thd at 200 watts.
Big deal.

Yet some people think so. They see that low figure and go ga-ga, not
realizing that THD is inaudible at a much higher figure, so paying the price
for a Halcro amp to get that low a figure is pointless.

As the HK audio club said,
"Ah, Halcro, it like 300B, but go louder!"



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.)

It is true that some advanced course work in calculus can be
of great help when designing systems with feedback. This
automatically disqualifies a great percentage of basement
geniuses and high end chief engineers, writers and
reviewers.

But not capable hands-on practical types who cobble up splendid amps with
FB

or without, and they never use calculus.



Unfortunately NFB doesn't come without a price. It levies
a cruel charge on the perceived quality of the sound.

And this can be demonstrated by what bias controlled listening tests that
have been performed by whom?


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

According to what bias controlled listening tests.

Strange that these supposedly unnatural-sounding amplifiers
can pass a straight wire bypass test, and so many low-NFB
power amps can't.

In other posts I have tendered my conditions where the "price"
may be indeed paid.

But ears are the final arbiter....

Then why not do the bias controlled, level matched listening tests that
would give some evidence to show that NFB or SS amps sound unnatural. One
thing is sure, SET's have gobs of THD at very low power. Typically 3-5% at
10 watts, which is definitely audible. So unless you have some horn
speakers with very high efficiency you are not going to have very clean
sound.

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

Because when applied with reasonable care by competent
engineers, NFB works. NFB got men to the moon. NFB makes
your car idle and run. NFB keeps your water heater from
exploding. It keeps your house and oven at the temperature
you set on your thermostat. NFB makes cell phones work.
etc., etc.

We are dealing with music, not rocket science, auto design,
plumbing, or phones..


In which case NFB makes amplifers work better and sound better.


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.

All areas where NFB is highly depended on, and it works.


Pick up any beginers book on electronics and you will find NFB described as
the most important method of reducing distortion in amplifiers. It reduces
gain because partof the signal is canceled, but ALL forms of distortion are
reducd in about the same proportion as the loss of gain. In addition the
amplifier is more stable with NFB.

The bottom line for amplifiers is that they be able to pass a signal without
any audible change. If using NFB accomplishes this goal and makes the amp
more stable, then it is a definite benefit and only if used incorectly
wouold it be a problem. Since there are so many amps using NFB that do not
have any audible distortion, what's the beef?



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.

But it's not just lower THD, it's all forms of distortion being lowered and
inproved amplifer stability.

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.

Usually the cat knows as much if not more about calculus
than the man,

Well I know all about hanging in and not giving up despite the peanut pay
of being an amp maker.
I don't use calculus though, and it wouldn't bring me any more bacon.
I don't have a cat.



The mechanism by which NFB wrecks your sound

NFB wrecks the sound the same way NFB makes your water
heater explode: as a rule it doesn't.

I have explained to some extent and under what conditions NFB may not be
as
bad as Jute makes out.

Fact is, you don't have to use it around triodes if you don't want to.
Jute's passionate language simply points to this fact.




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.

Nope. NFB is often dependent on frequency. As a rule it
reduces higher harmonics less.

An NFB network can be tailored to work on specific frequencies.


Jute said "in theory"
He didn't say it that was a fact that 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.

Actually, any order of nonlinear distortion, even Jute's
beloved order 2 can wreck the sound of music.

Indeed, but you need a lot more 2H to wreck music than say 7H .

I don't like distortion of any kind; it simply need be reduced to a low
enough level.
Its a case of the "enoughness" principle.





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.

This paragraph really says nothing.

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.

This is for all practical purposes, total BS. The bottom
line is that a power amp with a properly designed NFB loop
has far lower distortion of all relevant orders because of
the NFB.

If you have a high amount of open loop thd to start with
and poor bw and lots of phase shift then apply only
10dB of NFB, then the outcome could be sonically worse due to the
added harmonics in the spectra of the distortion, even though the
distortion

may measure a lower total.

SET amps with 0.5% 2H sound OK because that's the bulk of the thd.
Some amp with a total of 0.25% of 2H, 3H, 5H, 6H, 7H etc may sound a lot
worse.





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.

This is for all practical purposes, total BS. The bottom
line is that a power amp with a properly designed NFB loop
has far lower distortion of all relevant orders because of
the NFB.

Its not BS when low amounts of NFB are applied around
high open loop distortion amps, a few articles in Wireless World and
Electronics World
by reputable aurthors have explored and explained the phenonena.

But applying 60dB of NFB around a very poor open loop amp will
clean it up to measure well.

Many transistor amps are designed on this basis.

How it sounds is open to subjective evaluation, and not something I like
arguing.

It's something that can be determined by properly conducted, bias controlled
listening tests.
Match the levels and hide the DUT and compare.

One test done on some golden ear types showed that quick switching revealed
distortion and any differnce where long term listening without quick
swithcing and THD injected into the signal went un-noticed by the golden
ears.


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.)

This is for all practical purposes, total BS. The bottom
line is that a power amp with a properly designed NFB loop
has far lower distortion of all relevant orders because of
the NFB.


See above.


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.

This is for all practical purposes, total BS. The bottom
line is that a power amp with a properly designed NFB loop
has far lower distortion of all relevant orders because of
the NFB.

See above.

It should be remembered the author is talking about tube amps where
the amount of NFB is ulikely to be ever more than 20 dB.

So the artifacts after NFB has been applied are a more complex mix than
the
open loop Dn
products, and one has to weigh up if the FB was worth adding.
Certainly the total % if Dn is reduced when 20 db is aplied, and usually
it does give better sound; Quad II amps have
two overlapping loops, 8dB in the outout stage to linerarize the output
tube
misbehaviour,
and 12 db of blobal to linearize both the EF86 signal efforts and the
output
stage for a
total of 20 dB.

But I could easily build a triode amp with a pair of KT90 without any
global
NFB
or local internal FB and get 20 watts that would sound as well or probably
better than Quad II,
even though thd may measure a little higher.



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.

But, all orders of distortion will be greatly reduced.

With mild FB application and where there is high open loop THD, its
possible
to get an **increased** amount
of some harmonics when FB is added, eg, 2H may be reduced, but 3H is
increased,
and 4h and 5H are present in small amounts where there was none before the
FB as used.





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.

NFB reduces distortion at all output levels, large or small.

And they still use Negative Feedback? Are they stupid?

No, they are wise.

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.

In fact the inverse is true.

Not necessarily so.

It depends, and really wise men take all the variables into account...



But surely we don't have to do anything so stupid?

What's really stupid is avoiding NFB because of Jute's
senseless claims.

Read what you want to read....

The facts about NFB are simply not as Jute explains them. He is completely
100% wrong.
NFB reduces all forms of distortion and makes the amp more stable. This is
nopt Pavlovian or laziness on the part of engineers, it is good sound
engineering done to make the amp sound better and be more stable.

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.

In fact good designs with NFB start out with circuits that
have as low distortion as is practical before the addition
of NFB. See Self's blameless power amp circuit for many
examples of this.

But before NFB is applied the Dn is terrible if you include the Dn before
emitter follower connection is employed.

Then there are the macro Dn effects in the class A drive amp used in
nearly
all SS amps, so
Dn is always several % without global NFB, or about the same as a tube
amp.



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 fact triodes have built-in NFB.


And that's why loop or global FB can be left unconnected


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.)

Push-pull operation is in fact a great way to make power
amps more linear prior to the application of feedback.

Only if its class A.



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.

Actually it's because of the way tube amps react when clipped. The sine
wave still looks like a sine wave where a transistor amp driven to clipping
begins to look like a square wave and sounds like ****. Solution get a more
powerful transistor amp or don't drive your amp to clipping.


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.

If you did it because of Jute's posturing, you're an old
kind of fool.

Can we prove any of this scientifically?

Hard to do because Jute's so-called scientific claims are
bogus.

We have already.

LOL!

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.

That someone might have a prefence for an amp that has oodles of distortion
does not mean that such amps are good. The object of amplification is to do
so without any audible distortion so that the music is heard as it was
recorded. If someone wants to muck it up with distortion after that it's
their choice, but you could accmplish that much easier by sticking a 1 ohm
resistor in series to the speakers.


Show us your level-controlled, bias-controlled listening
tests, Andre.

Science also proceeds by pure reason.

Actually, science proceedes by both pure reasoning and
practical experience.

And listening tests.
These suggest triode amps without loop NFB are not always bad as the
Kroogers and Wilsons
of the world suggest.

Depends on what you consider bad. If it isn't passing a straight wire
bypass, it's bad.

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.

NFB lowers all relevant forms of distortion. Distortion is
one of those things where less is more.

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

Absolute BS. Transistor amps without NFB were built in the
early days, before the refinements that enable the use of
NFB are possible.

What do I say?

Never were transistor amps sold without NFB.

Nobody ever sold solid state pure current source amplifiers with Ro many
times higher than speaker Z.

The day after they built the first transistor, and measured it, they knew
lots of FB would be needed
to lineraize the awful non linearity of such devices.







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.

Seneseless posturing.

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.

More senseless posturing.

Take it or leave it.




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.

And, SS high feedback amps are what they use as a rule.

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

Wrong. NFB can work well at both low and high levels.

Nyobi, Queen of Mindless Stubbornnes, I have read your post to the end.
You'are absolutely right. If people misuse tubes, as in your example of
running some poor little 300B at 10W (aargh! what an eejit), they will
sound like ****. Like you, I abhor noise. Those who aren't willing to
go the whole hog and spend the money to make their entire system flat
should not be in tube amps and particularly not in SET. That either
means a 75W SET amp to drive panels, such as I built, or it means
running the SET amp where it is flat into horns. If you don't have the
commitment or the DIY skill or the money, you should be in solid state,
not in tubes, definitely not in SET.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"an unbelievably comprehensive web site" -- Hi-Fi News & Record Review

wrote:
"Patrick Turner" wrote in message
...


Sander deWaal wrote:

"Andre Jute" said:

Good heavens. I couldn't believe that was his entire argument so I went
back to look up Graham's post. (I normally don't open the posts of the
more useless posters.) I wish you luck, Patrick, in extracting sense
from Poop Bear; if you do, you are better man than me, Gunga Din. Since
you're such saint, maybe you can next work on the other superstar of
the debating society whom I also found -- I quote his entire post:

snip

Just look what Arny had to say to one of your posts about the use of
NFB ....the original was posted to RAO by our friend Brat Ludwig :-)

- begin long quote -

Arny Krueger said:

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.

Good example of Jute's ignorance of the engineering
education process. Feedback is usually taught as it relates
to automatic control systems. Last time I looked courses
like these generally fit into the junior or senior years.

In short the idea that "He learns to say '100dB of NFB in
his sleep before he
finishes his first week at the most humble polytechnic" is
sheerist BS.

Its not BS.

Even I have built plenty of fair sounding SS amps with a total of 100dB
of NFB, and many commercial designs use this much.

First you have the emitter follower output stage and there is 40 dB, and
then there is often 60
dB of global, so there is your 100dB; its very standard practice and i
suggest a good read of Douglas Self's
site to understand it better.
Without any global NFB it only takes about 2mV of input for clipping at
100
watts;
thats typical Linn topology open loop gain in SS amps.



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.

Good example of Jute's ignorance of feedback. It's highly
unlikely that one could apply 50 dB loop feedback to a power
amp with an output transformer and still have acceptable
stability.

But a wannabe suggested Jute use the 50 dB more gain and FB.
Jute was refuting the wannabe's recomendation.

It is almost impossible to apply 50 dB of global FB in any OPT coupled
amp. Jute knows this.



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 amount of rediculous posturing can counter the fact that
NFB can be made to work very well and to great advantage,
thank you.

Yes, agreed, but you still don't have to use global FB if you don't want
to
around triode amps .
Jute may take his time to get to the point, but triodes CAN be used
without
loop FB.
Transistors, mosfets, and pentodes and tetrodes cannot.

Triodes have their own internal electrostatic loops of FB which one cannot
avoid,
but which are the most natural form of FB known and can be best exploited
by
keeping
load values high with respect to Ra.
It is why they are so linear when loaded in a signal voltage amp with a
CCS
load.



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.

If the kiss amp has less than 0.05% nonlinear distortion
with any power level or any frequency or combination of
frequencies 20-20 KHz, then its fine as is. I doubt it is
that good.

Ah, the doubters. If only they could listen to an 845 Bel Canto or some
such
amp......



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.

This is a highly incomplete explanation. In fact the voltage
fed back offsets not only the distortion but a goodly part
of the basic signal. Therefore, NFB generally reduces an
amplifier's gain for both the basic amplfied signal and also
the distortion.


NFB is better explained in the old books, but newbies cannot be expected
to
understand first off
all the mumbo jumbo of old books.
Jute is trying to make ideas of NFB seem understandable.

Almost nobody I meet who is not a tech has the slightest idea of the basic
gain/FB equation,
ie, that
gain with FB = A / ( 1 + [A x ß] )
So how do you introduce ideas about FB?






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.

In fact NFB properly applied reduces, not increases an
amplifier's phase shift.

Indeed this is true.



'Wow!' those meeting NFB for the first time will now say,
'Something for free! I'll grab some of that for my amp.'

Just just contrdicted the first phrase in the previous
paragraph that says that NFB has a price in the form of a
loss of gain.

A misunderstanding.
NFB is a technique that reduces thd/imd/phase shift for nothing, almost.
But you must pay for the greater open loop gain needed.
Simple.





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.

Jute's mistake here is that its not heresy to question
measurements, and people have been doing that for decades,
even in such conservative journals as the JAES.

It is ok to question measurements.
But Jute is on the side of the questioner, he is mocking the
slavish devotion to measurements in so many
engineering minds.
Halcro amps make 0.0001% thd at 200 watts.
Big deal.

Yet some people think so. They see that low figure and go ga-ga, not
realizing that THD is inaudible at a much higher figure, so paying the price
for a Halcro amp to get that low a figure is pointless.

As the HK audio club said,
"Ah, Halcro, it like 300B, but go louder!"



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.)

It is true that some advanced course work in calculus can be
of great help when designing systems with feedback. This
automatically disqualifies a great percentage of basement
geniuses and high end chief engineers, writers and
reviewers.

But not capable hands-on practical types who cobble up splendid amps with
FB

or without, and they never use calculus.



Unfortunately NFB doesn't come without a price. It levies
a cruel charge on the perceived quality of the sound.

And this can be demonstrated by what bias controlled listening tests that
have been performed by whom?


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

According to what bias controlled listening tests.

Strange that these supposedly unnatural-sounding amplifiers
can pass a straight wire bypass test, and so many low-NFB
power amps can't.

In other posts I have tendered my conditions where the "price"
may be indeed paid.

But ears are the final arbiter....

Then why not do the bias controlled, level matched listening tests that
would give some evidence to show that NFB or SS amps sound unnatural. One
thing is sure, SET's have gobs of THD at very low power. Typically 3-5% at
10 watts, which is definitely audible. So unless you have some horn
speakers with very high efficiency you are not going to have very clean
sound.

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

Because when applied with reasonable care by competent
engineers, NFB works. NFB got men to the moon. NFB makes
your car idle and run. NFB keeps your water heater from
exploding. It keeps your house and oven at the temperature
you set on your thermostat. NFB makes cell phones work.
etc., etc.

We are dealing with music, not rocket science, auto design,
plumbing, or phones..


In which case NFB makes amplifers work better and sound better.


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.

All areas where NFB is highly depended on, and it works.


Pick up any beginers book on electronics and you will find NFB described as
the most important method of reducing distortion in amplifiers. It reduces
gain because partof the signal is canceled, but ALL forms of distortion are
reducd in about the same proportion as the loss of gain. In addition the
amplifier is more stable with NFB.

The bottom line for amplifiers is that they be able to pass a signal without
any audible change. If using NFB accomplishes this goal and makes the amp
more stable, then it is a definite benefit and only if used incorectly
wouold it be a problem. Since there are so many amps using NFB that do not
have any audible distortion, what's the beef?



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.

But it's not just lower THD, it's all forms of distortion being lowered and
inproved amplifer stability.

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.

Usually the cat knows as much if not more about calculus
than the man,

Well I know all about hanging in and not giving up despite the peanut pay
of being an amp maker.
I don't use calculus though, and it wouldn't bring me any more bacon.
I don't have a cat.



The mechanism by which NFB wrecks your sound

NFB wrecks the sound the same way NFB makes your water
heater explode: as a rule it doesn't.

I have explained to some extent and under what conditions NFB may not be
as
bad as Jute makes out.

Fact is, you don't have to use it around triodes if you don't want to.
Jute's passionate language simply points to this fact.




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.

Nope. NFB is often dependent on frequency. As a rule it
reduces higher harmonics less.

An NFB network can be tailored to work on specific frequencies.


Jute said "in theory"
He didn't say it that was a fact that 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.

Actually, any order of nonlinear distortion, even Jute's
beloved order 2 can wreck the sound of music.

Indeed, but you need a lot more 2H to wreck music than say 7H .

I don't like distortion of any kind; it simply need be reduced to a low
enough level.
Its a case of the "enoughness" principle.





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.

This paragraph really says nothing.

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.

This is for all practical purposes, total BS. The bottom
line is that a power amp with a properly designed NFB loop
has far lower distortion of all relevant orders because of
the NFB.

If you have a high amount of open loop thd to start with
and poor bw and lots of phase shift then apply only
10dB of NFB, then the outcome could be sonically worse due to the
added harmonics in the spectra of the distortion, even though the
distortion

may measure a lower total.

SET amps with 0.5% 2H sound OK because that's the bulk of the thd.
Some amp with a total of 0.25% of 2H, 3H, 5H, 6H, 7H etc may sound a lot
worse.





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.

This is for all practical purposes, total BS. The bottom
line is that a power amp with a properly designed NFB loop
has far lower distortion of all relevant orders because of
the NFB.

Its not BS when low amounts of NFB are applied around
high open loop distortion amps, a few articles in Wireless World and
Electronics World
by reputable aurthors have explored and explained the phenonena.

But applying 60dB of NFB around a very poor open loop amp will
clean it up to measure well.

Many transistor amps are designed on this basis.

How it sounds is open to subjective evaluation, and not something I like
arguing.

It's something that can be determined by properly conducted, bias controlled
listening tests.
Match the levels and hide the DUT and compare.

One test done on some golden ear types showed that quick switching revealed
distortion and any differnce where long term listening without quick
swithcing and THD injected into the signal went un-noticed by the golden
ears.


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.)

This is for all practical purposes, total BS. The bottom
line is that a power amp with a properly designed NFB loop
has far lower distortion of all relevant orders because of
the NFB.


See above.


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.

This is for all practical purposes, total BS. The bottom
line is that a power amp with a properly designed NFB loop
has far lower distortion of all relevant orders because of
the NFB.

See above.

It should be remembered the author is talking about tube amps where
the amount of NFB is ulikely to be ever more than 20 dB.

So the artifacts after NFB has been applied are a more complex mix than
the
open loop Dn
products, and one has to weigh up if the FB was worth adding.
Certainly the total % if Dn is reduced when 20 db is aplied, and usually
it does give better sound; Quad II amps have
two overlapping loops, 8dB in the outout stage to linerarize the output
tube
misbehaviour,
and 12 db of blobal to linearize both the EF86 signal efforts and the
output
stage for a
total of 20 dB.

But I could easily build a triode amp with a pair of KT90 without any
global
NFB
or local internal FB and get 20 watts that would sound as well or probably
better than Quad II,
even though thd may measure a little higher.



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.

But, all orders of distortion will be greatly reduced.

With mild FB application and where there is high open loop THD, its
possible
to get an **increased** amount
of some harmonics when FB is added, eg, 2H may be reduced, but 3H is
increased,
and 4h and 5H are present in small amounts where there was none before the
FB as used.





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.

NFB reduces distortion at all output levels, large or small.

And they still use Negative Feedback? Are they stupid?

No, they are wise.

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.

In fact the inverse is true.

Not necessarily so.

It depends, and really wise men take all the variables into account...



But surely we don't have to do anything so stupid?

What's really stupid is avoiding NFB because of Jute's
senseless claims.

Read what you want to read....

The facts about NFB are simply not as Jute explains them. He is completely
100% wrong.
NFB reduces all forms of distortion and makes the amp more stable. This is
nopt Pavlovian or laziness on the part of engineers, it is good sound
engineering done to make the amp sound better and be more stable.

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.

In fact good designs with NFB start out with circuits that
have as low distortion as is practical before the addition
of NFB. See Self's blameless power amp circuit for many
examples of this.

But before NFB is applied the Dn is terrible if you include the Dn before
emitter follower connection is employed.

Then there are the macro Dn effects in the class A drive amp used in
nearly
all SS amps, so
Dn is always several % without global NFB, or about the same as a tube
amp.



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 fact triodes have built-in NFB.


And that's why loop or global FB can be left unconnected


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.)

Push-pull operation is in fact a great way to make power
amps more linear prior to the application of feedback.

Only if its class A.



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.

Actually it's because of the way tube amps react when clipped. The sine
wave still looks like a sine wave where a transistor amp driven to clipping
begins to look like a square wave and sounds like ****. Solution get a more
powerful transistor amp or don't drive your amp to clipping.


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.

If you did it because of Jute's posturing, you're an old
kind of fool.

Can we prove any of this scientifically?

Hard to do because Jute's so-called scientific claims are
bogus.

We have already.

LOL!

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.

That someone might have a prefence for an amp that has oodles of distortion
does not mean that such amps are good. The object of amplification is todo
so without any audible distortion so that the music is heard as it was
recorded. If someone wants to muck it up with distortion after that it's
their choice, but you could accmplish that much easier by sticking a 1 ohm
resistor in series to the speakers.


Show us your level-controlled, bias-controlled listening
tests, Andre.

Science also proceeds by pure reason.

Actually, science proceedes by both pure reasoning and
practical experience.

And listening tests.
These suggest triode amps without loop NFB are not always bad as the
Kroogers and Wilsons
of the world suggest.

Depends on what you consider bad. If it isn't passing a straight wire
bypass, it's bad.

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.

NFB lowers all relevant forms of distortion. Distortion is
one of those things where less is more.

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

Absolute BS. Transistor amps without NFB were built in the
early days, before the refinements that enable the use of
NFB are possible.

What do I say?

Never were transistor amps sold without NFB.

Nobody ever sold solid state pure current source amplifiers with Ro many
times higher than speaker Z.

The day after they built the first transistor, and measured it, they knew
lots of FB would be needed
to lineraize the awful non linearity of such devices.







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.

Seneseless posturing.

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.

More senseless posturing.

Take it or leave it.




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.

And, SS high feedback amps are what they use as a rule.

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

Wrong. NFB can work well at both low and high levels.