[Patrick Turner]

I am speaking about the facts of the engineering.

So your example of an SS amp produces 5% THD without feedback,
yet you say that to produce less than 10% is extremely difficult.
I needn't go and measure anything, I'll just use your example to
show that you are being very silly.

You sound like a man who has NEVER designed or built any amplifiers, and
you are just cruising for a bruising.

Where is your website outlining your achievements and depth of
knowledge?

Are you just nit picking ignoramus?

Without any NFB whatsoever, local or loop current current or voltage, a
BJT amp has perhaps 10% THD.

Just try connecting up ONE lone BC546, use a basic common emitter gain
stage with resistor collector load
and 30V supply, so that the collector idles at 15Vdc.
Make sure you have ZERO emitter resistance included, or if you must have
an emitter resistor,
bypass it with 1,000uF, to ensure there is no ac NFB present.
Measure the THD with a sine wave at 9Vrms output.

When you have done this experiment, talk to me about BJT linearity.

How would you improve the bloody awful performance?

Build an additional 6SN7 gain stage using a 250V supply,
and anode idling at 110Vdc, and with bypassed cathode R and let me know
your THD results at 9Vrms output.

If you were skilled and zealous, you'd do the experiments with a j-fet,
as well but
I don't think you are capable of anything except nit picking for the
sake of it
unless you proove otherwise.

Patrick Turner.



--
Eiron.

[Patrick Turner]

Arny Krueger wrote:

"Patrick Turner" wrote in message


In fact SS amps have appalling open loop performance,
high THD/IMD, poor phase shift character, lousy bandwidth,
and lots of noise, and perhaps appallingly high output
resistance.

This is true only if you design SS amps in accordance with Patrick's rules
for intentionally designing crappy amps.

The stupid arsolic Arny misrepresents me yet again.

Stop lying Arny.

If you don't use any applied NFB anywhere Arny, local or loop,
you end up with severely crap performance from anything solid state.
Many designers have done just that, then they connect a loop of global
NFB and
presto, all the performance faults nearly vanish.

I did not draw up any rules for designing crap amps.

Perhaps its something you might do though...



It's possible to optimize a SS amp for good open loop performance. This
isn't done very much because it would be a really stupid thing.

Oh, really, but its what many designers really do;
they linearize as much as possible with local FB and enable
low THD below 10% without any loop FB, then the loop FB cleans up the
result.

If the output BJTs are running in emitter follower, that's 40dB local
series voltage NFB,
then another 60 dB of applied global series voltage NFB makes the output
stage
governed by a total of 100dB of series voltage NFB.

Perhaps you are ignorant of the methods used by Douglas Self, Linsly
Hood, and many others.


In essence, what Patrick is telling us is that the only way he can come up
with a favorable comparisons between tubed and SS amps is to force the SS
amp to be designed in accordance with 2 sets of stupid rules.

The first stupid rule of Patrick's is that the SS amp must be designed
without loop feedback.

I said no such thing; what i said was that to see the awful natural
voltage linearity bjts have,
don't use any NFB.

You are grossly stupid for lying to the public by saying I invented
rules.
I clearly didn't.

Everyone knows just how slimy Arny is, and what an arsole ****head.
Sorry Arny, but you really deserve an award for being a slimy AH.



The second stupid rule of Patrick's is that the SS amp must be designed
without local feedback of the usual kinds.


Again Slimy Arsole lies again.



NFB reduces all the defects by the amount of NFB used,
and typically its 60dB, so that where you see that THD =
0.005% at a db below clipping,
without NFB the same amp makes THD = 5% at the same power.

This would work for either tubes or transistors. You don't see a lot of
tubed amps with 60 dB NFB for two reasons:

(1) It's hard to get enough excess gain with tubes to sacrifice 60 dB or
gain, no matter how good the reason.


There is never any need to have 60dB around a single tube amplifier.

The natural linearity without ANY local FB permits mild NFB applications
for good results.

(2) Tubed amps tend to have too much phase shift to have 60 dB NFB and still
be stable.

Indeed, but there is no need for 60dB.

In a McIntosh amp, the output stage is subject to
about 15db of local NFB in its output stage, and 20db of global NFB,
making a total of 35dB. There is more if no load is connected, but
these amps have about the most NFB that can be used with any tube amp.
The EAR509 is another example.
both McIntosh and EAR amps operate the output tubes in near class B
conditions
like the way BJT transistors are used, ie, away from their MOST
natural and linear operating curve condition. Hence more FB is applied
than
in an amp with mainly class A operation.

but if someone want to use a McIntosh with say a 16 ohms speaker tied to
the
4 ohm outlet, then the load seen by the tubes becomes 4 times higher,
and becomes a class A load
and the already miniscule THD/IMD reduce to truly low amounts.

But there has never been a need for any more than 20dB of applied loop
NFB
around a tube amp mainly working in class A. Quad, Leak, Radford,
Dynaco, VTL
and many others have successfully followed this rule that I most
certainly never invented.

A Williamson triode amp has a lot of inherent FB in its output stage
when KT66 are strapped as triodes, so "open loop"
thd in triode mode is 1% at 1dB below clipping, at 12 watts.
20dB global reduces this to 0.1%.
At 1.2 watts, when the output voltage = 1/3 of the 12 watt voltage, THD
is 0.03%, and needn't be any lower, because with class A amps
THD/IMD reduces with reducing output voltage.

If you want more power and less THD/IMD, then use a quad of KT90 or
300B.

With a solid state amp, it is normal for many designers to apply
local NFB from the output of the VAS stage collector to its base input
via
a small value capacitor of perhaps 100pF.
This then ensures the open loop HF response is attenuated by 6dB/octave
above a LF pole
as low as 100Hz, so that the amp has high open loop gain at below this
LF pole,
and by 20khz, the open gain has dropped perhaps 46dB, so that if there
was 60dB of global NFB applied,
it is only applied at 100Hz or below, and that at 20khz, there is
perhaps only 14dB, less than
found in a typical tube amp.

Why is the open loop gain of BJT amps so drastically limited by the gain
tailoring
local loop FB?

Its because otherwise the amp would be unstable.

Of course one does not need to have a high amount of NFB applied above
20kHz.
The first THD product is 40kHz, but problems of IMD products appearing
below 20kHz remain.

Then there are designers like Bruce Candy who designed Halco amplifiers
which manage 0.0001% or less thd at 1dB below cippling, 200 watts at
20kHz or better below 20khz.

Bruce knows a shirtload more about SS amplifier designing than than Arny
will ever ever know.



Perhaps Arny has never ever built a tube amp successfully, and talks
through his arsole, which
slimily distorts the sound of his messages.




I am speaking about the facts of the engineering.

Subject to some absolutly crazy rules.

You are the net's greatest arsole who quickly resorts to telling tales
of BULL**** about what people said, or didn't say.




I have led myself to think NFB allows devices to sing
the way they were meant to.

It works for either tubes or transistors.

BTW Arny, if for ONE second you can stop yourself being a Slimy AH,
try quoting all my post without snipping and cutting it to ribbons.

Patrick Turner.

[John Byrns]

In article ,
Patrick Turner wrote:

I am speaking about the facts of the engineering.

So your example of an SS amp produces 5% THD without feedback,
yet you say that to produce less than 10% is extremely difficult.
I needn't go and measure anything, I'll just use your example to
show that you are being very silly.

You sound like a man who has NEVER designed or built any amplifiers, and
you are just cruising for a bruising.

Where is your website outlining your achievements and depth of
knowledge?

Are you just nit picking ignoramus?

Without any NFB whatsoever, local or loop current current or voltage, a
BJT amp has perhaps 10% THD.

Just try connecting up ONE lone BC546, use a basic common emitter gain
stage with resistor collector load
and 30V supply, so that the collector idles at 15Vdc.
Make sure you have ZERO emitter resistance included, or if you must have
an emitter resistor,
bypass it with 1,000uF, to ensure there is no ac NFB present.
Measure the THD with a sine wave at 9Vrms output.

When you have done this experiment, talk to me about BJT linearity.

How would you improve the bloody awful performance?

Build an additional 6SN7 gain stage using a 250V supply,
and anode idling at 110Vdc, and with bypassed cathode R and let me know
your THD results at 9Vrms output.

If you were skilled and zealous, you'd do the experiments with a j-fet,
as well but
I don't think you are capable of anything except nit picking for the
sake of it
unless you proove otherwise.

Patrick, to make this a fair apples and apples experiment the 6SN7, with
it's 250 volt power supply, should be measured with a 75vrms output.
Also you haven't specified the nature of the input input signal which I
am sure you intended a voltage, but a current input may be more
favorable for the BC546, but you didn't rule it out.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Patrick Turner]

John Byrns wrote:

In article ,
Patrick Turner wrote:

I am speaking about the facts of the engineering.

So your example of an SS amp produces 5% THD without feedback,
yet you say that to produce less than 10% is extremely difficult.
I needn't go and measure anything, I'll just use your example to
show that you are being very silly.

You sound like a man who has NEVER designed or built any amplifiers, and
you are just cruising for a bruising.

Where is your website outlining your achievements and depth of
knowledge?

Are you just nit picking ignoramus?

Without any NFB whatsoever, local or loop current current or voltage, a
BJT amp has perhaps 10% THD.

Just try connecting up ONE lone BC546, use a basic common emitter gain
stage with resistor collector load
and 30V supply, so that the collector idles at 15Vdc.
Make sure you have ZERO emitter resistance included, or if you must have
an emitter resistor,
bypass it with 1,000uF, to ensure there is no ac NFB present.
Measure the THD with a sine wave at 9Vrms output.

When you have done this experiment, talk to me about BJT linearity.

How would you improve the bloody awful performance?

Build an additional 6SN7 gain stage using a 250V supply,
and anode idling at 110Vdc, and with bypassed cathode R and let me know
your THD results at 9Vrms output.

If you were skilled and zealous, you'd do the experiments with a j-fet,
as well but
I don't think you are capable of anything except nit picking for the
sake of it
unless you proove otherwise.

Patrick, to make this a fair apples and apples experiment the 6SN7, with
it's 250 volt power supply, should be measured with a 75vrms output.
Also you haven't specified the nature of the input input signal which I
am sure you intended a voltage, but a current input may be more
favorable for the BC546, but you didn't rule it out.

Regards,

John Byrns

John, I am not being unfair to the little BJT by comparing it to a big
6SN7 triode tube.

If we are using a BC546 to make 1Vrms output for a line stage preamp,
we may use only a 30V supply.

We would use 250V supply for the 6SN7 to DO EXACTLY THE SAME TASK.

As a bonus, the 6SN7 could make 75Vrms, well in excess of what the BC546
could do.

If we wanted 75Vrms from a BJT, we'd use an MJ340 with a 250V supply,
but when we
rigged it to make 75vrms without any NFB whatsoever, the MJE340 BJT
would have much worse
THD/IMD than the 6SN7.

It is patially because of the higher dynamic range that the triode
performance
is better than a BC546.

THD of the triode might be 5% at 75vrms, and at 1Vrms, expect about
0.033%, mainly all 2H.
but if the triode was loaded with a CCS, the 75vrms Dn may reduce to 1%,
giving 0.01% at 1Vrms, and all without any type of global or local NFB.
using the two triodes inside a 6SN7 as a balanced pair of tubes the
distortion
of 0.01% can be reduced a further 10dB at least because the 2H cancels
out,
and agin, its all without any NFB and its all much better ta what is
possible with BJTs without
any NFB.

This is fact, not fiction.

If we then allow NFB in the BJT circuit we can reduce its THD/IMD a lot.

We would also find the BJT would have low base input resistance.
And non linear resistance as well.

The use of a darlington pair of MJE340 plus an emitter resistance to
give a lot of local NFB,
perhaps 30dB,would reduce THD of the BJT to be perhaps better than the
triode for
equal gain figures.

I suggest people
get off their fat lazy arses to find out the realities for themselves,
instead of nit picking what I have said.

They may find the BJT darlington pair even with an emitter resistor
has a complex spectra of distortion products at high levels of output,
very much like a pentode tube.

Engineers welcomed opamps onto the scene because internal gain was so
muchy higher
and and more NFB could be used than in discrete circuits using
single/double BJT arrays.

Someone maintained the opamps sounded better, but that's a moot point as
well....

Patrick Turner.



--
Surf my web pages at, http://fmamradios.com/

[Phil]

Patrick Turner wrote:


It seems to me Cheever tries to show that the ears will produce harmonic
voltages from the
hairs in the cochlea in your ear when a pure tone is used as a signal.
The brain he says, filters out the harmonics, and we hear the tone as
pure.

To me this defies common sense, because it implies the brain would do a
lot of filtering
with music or noise which is riddled with many harmonics.
Humans are notoriously erroneous creatures. God isn't perfect, let alone
understandable,
if we take a look at his creations over the millions of years or trial
and error.

But if Cheever is correct, and the brain does away with much of what the
ear microphones feed to it
then its easy to see how MP3 formatted sound gets away with it...

Our knowledge of how things work often leads, incorrectly, to
conclusions like, the "mind" turns the image on our retina around so
that we don't see the world "upside down." However, as infants, nothing
"told our brain" which side of our retina was up or down, so it simply
learned to perceive the world, correctly, when images of the sky landed
on what we KNOW, as adults, is the bottom of the retina. In the case of
pure tones, the ear sends a signal to the brain that includes harmonics,
but to our brain, that's what a pure tone sounds like! When we hear an
"impure" tone, our ears send different signals to the brain, and we hear
a difference, with no need -- and for that matter no way -- to "filter
out" the harmonics. Having never received a pure sine wave signal from
our ears, how would our brain "know" how to filter out anything? And why
would it want to? Is there a business where a company can brag that
"this brain filters out 99% of the ear's harmonics!"

In other words, we forget that as infants, our brain ADAPTED to whatever
signals our senses sent it, and those signals became standard, normal.
However, the idea that our brains ALWAYS hear harmonics makes it easier
to understand why harmonics don't bother people that much; instead of
hearing the difference between 0% and 5% THD, the signals to our brains
vary from, say, 5% to 7.2% THD (I think THD adds in an RMS manner, hence
the change of 7.2% instead of 10%), obviously a much less drastic change!

After a brief glance, it LOOKS like a good paper, the result of honest,
intelligent research, one worth using in amp design until either (1) you
find a better paper, or (2) you find various tricks and techniques that
add to and/or improve upon the techniques he proposes.

Phil

[Ian Bell]

Patrick Turner wrote:

Without any NFB whatsoever, local or loop current current or voltage, a
BJT amp has perhaps 10% THD.

Just try connecting up ONE lone BC546, use a basic common emitter gain
stage with resistor collector load
and 30V supply, so that the collector idles at 15Vdc.
Make sure you have ZERO emitter resistance included, or if you must have
an emitter resistor,
bypass it with 1,000uF, to ensure there is no ac NFB present.
Measure the THD with a sine wave at 9Vrms output.

When you have done this experiment, talk to me about BJT linearity.


That test is a trifle unfair as you are asking the BJT to swing 25V from a
30V supply. However I have set up a circuit with a single BJT, no NFB, 60V
rail. 2nd harmonic is 36dB down i.e just over 1.5%. Higher harmonics are
progressively lower. Nowhere near the 10% you mentioned.

Next question.

Ian

[Patrick Turner]

Ian Bell wrote:

Patrick Turner wrote:

Without any NFB whatsoever, local or loop current current or voltage, a
BJT amp has perhaps 10% THD.

Just try connecting up ONE lone BC546, use a basic common emitter gain
stage with resistor collector load
and 30V supply, so that the collector idles at 15Vdc.
Make sure you have ZERO emitter resistance included, or if you must have
an emitter resistor,
bypass it with 1,000uF, to ensure there is no ac NFB present.
Measure the THD with a sine wave at 9Vrms output.

When you have done this experiment, talk to me about BJT linearity.


That test is a trifle unfair as you are asking the BJT to swing 25V from a
30V supply.

When did I ever say try to swing 25Vrms????

if you have a +30V supply, with Ec at +15V, then all you would get is
+/- 12V peak approximately,
or around 9Vrms, which is what I recall I said.



However I have set up a circuit with a single BJT, no NFB, 60V
rail. 2nd harmonic is 36dB down i.e just over 1.5%. Higher harmonics are
progressively lower. Nowhere near the 10% you mentioned.

All the bjts I have tested go an awful lot worse than you say.

They are disgustingly non linear.


Probably you have an emitter resistor which you have not bypassed to
avoid the local NFB.

Please present your schematic and post it to your home page for all to
see with
all operating voltages. We'd all sure like to duplicate your experiment
to verify your claims.



Next question.

Its "why have you not prooved your claim is true?"


Patrick Turner.



Ian

[Arny Krueger]

"Sander deWaal" wrote in message

"Arny Krueger" said:

"Sander deWaal" wrote in message

John Byrns said:


The usual outcome: those who like tubes agreed with most
of it, those who loathe tubes disagreed with most of it.


Typical of Sander's overly-confrontational approach to
technology he can't properly understand.

ROFL!!

That's why I design amps for a living, and you fix
computers and work on your "usenet career", hmmm? ;-)

You design amps for a living, Sander?

Do tell!

[Arny Krueger]

"Patrick Turner" wrote in message


Arny Krueger wrote:

You have never built a BJT based amplifier
without some external loop NFB, such as the emitter
follower connection et all.

Emitter followers are evil, but cathode followers aren't?

LOL!

Emitter resistors are loop feedback? On what planet?

Emitter resistors are used in many SS amps as local
applications of series current NFB to linearize the
otherwise appalling voltage linearity
of BJTs.

I've been professionally trained in designing SS amplifiers since 1966.
Virtually the first words out of the professor's mouth even way back then
was that unlike tubes, BJTs were current-driven devices. The second class
was about how to use emitter resistors to obtain bias stability. After that,
it was pointed out that you may bypass all or part of the emitter resistor
in order to get higher AC gain.

You're throwing more than a half-century of wisdom about BJTs in order to
even raise this issue, Patrick.

They also raise the effective base input
resistance, appallingly
low without such NFB.

So what?

These local NFB apps ARE local LOOP FB.

Local loop FB is an oxymoron. There is local feedback within a stage and
there is loop feedback that encompasses multiple stages. That's the standard
terminology, and has been for over 50 years. Tubes, transistors, or what,
doesn't matter.

Do not try to evade the issue that it is impossible to
build a listenable bjt amp without loop NFB of some kind, or
external NFB of any kind.

Only true given a totally contrived and non-standard abuse of standard
terminology. IOW, never true in the real world.

NOW READ ME CAREFULLY, ARNY, A TYPICAL 6SN7 DOES NOT NEED
ITS CATHODE RESISTOR TO BE UNBYPASSED
TO PROVIDE LINEARISING LOCAL NFB, YOU GOT IT!!?

Well, there's to use your teminology Patrick, this local feedback loop
involving a cloud of electrons between the plate and the grid. Yup, there's
your feedback loop. One irony is that this cloud of electrons can easily be
thousands of times physically larger than its equivalent in an IC.

I am saying this is not necessary with triodes. There is
a distinction and please do not misrepresent what i
said.

You kept piling on nonesensical distinctions after I
responded.

You keep lying arny, and acting like slime, and your
reputation follows you.

I called you a liar first Patrick, This is just a lame come-back.

There' no chance of a rational discussion with someone that is as deep into
self-serving falisifcation and deception as you, Patrick.

[Arny Krueger]

"Patrick Turner" wrote in message

I am speaking about the facts of the engineering.

So your example of an SS amp produces 5% THD without
feedback, yet you say that to produce less than 10% is
extremely difficult. I needn't go and measure anything,
I'll just use your example to show that you are being
very silly.

You sound like a man who has NEVER designed or built any
amplifiers, and you are just cruising for a bruising.

Where is your website outlining your achievements and
depth of knowledge?

You mean he loses points for not publicly bragging about himself?

LOL!

[Arny Krueger]

"Patrick Turner" wrote in message


Perhaps Arny has never ever built a tube amp
successfully.

I built my first tube amp from scratch some place around 1959. I ran it for
about three years until I built something better. It was successful enough
for me for about three years.

[John Byrns]

In article ,
Patrick Turner wrote:

Ian Bell wrote:

Patrick Turner wrote:

Without any NFB whatsoever, local or loop current current or voltage, a
BJT amp has perhaps 10% THD.

Just try connecting up ONE lone BC546, use a basic common emitter gain
stage with resistor collector load
and 30V supply, so that the collector idles at 15Vdc.
Make sure you have ZERO emitter resistance included, or if you must have
an emitter resistor,
bypass it with 1,000uF, to ensure there is no ac NFB present.
Measure the THD with a sine wave at 9Vrms output.

When you have done this experiment, talk to me about BJT linearity.


That test is a trifle unfair as you are asking the BJT to swing 25V from a
30V supply.

When did I ever say try to swing 25Vrms????

When did Ian ever say you said to try to swing 25Vrms???? He said "to
swing 25V" which I took to mean 25 volts peak to peak.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Patrick Turner]

Arny Krueger wrote:

"Patrick Turner" wrote in message


Perhaps Arny has never ever built a tube amp
successfully.

I built my first tube amp from scratch some place around 1959. I ran it for
about three years until I built something better. It was successful enough
for me for about three years.


Iv'e tried to read the other 3 posts by Slimy Arsole Arny, but I could
not find anything worth replying to.
Arny has the inflexible dull mindset like so many Old Bulls who ****
around the Internet all day to mark their territory,
and who trample any dissident or thinking person down into the mud with
glee.
Anyone who thinks differently to Arny is wrong, according to Arny AH.


In his other recent posts there are many examples of gross and carefully
expressed misconcenptions lies, inuendo,
technical errors, clangers, misrepresentations, and unadulterated
bull****.

There is a complete lack of any attempt to inform members of the public
towards any better understanding of
distortions in amplifiers, enabling them to built better functioning
amplifiers. Nothing.


He can say whatever he likes, it is impossible to discuss anything with
him, his mind is fossilised,
and as solid as pn junction.


Arny feels he must be seen by himself as being seen to be right, while
all the rest of laugh at Arny the Clown,
who must feel utterly alone and threatened when someone else challenges
him, and nobody wants to engage in any
social intercourse with him.

Is there an 'Arny' brand of amplifier on the market?

Meanwhile I should not waste more time pointlessly crushing Arny AH's
BS,
but devote what small amount of valuable time I have to those who can
think outside the square a bit
and who are not threatened by radical ideas.

Patrick Turner.

[Phil Allison]

"Arny Krueger"

There' no chance of a rational discussion with someone that is as deep
into self-serving falsification and deception as you, Patrick.


** Boy, oh boy - ain't that the TRUTH.

The " Turneroid " public menace is not so named without reason.

Relates to terms like:

Android, Haemorrhoid & Mongoloid.

Cos the ASS is all of those.



BTW:

My earlier, personal MESSAGE to the Turneroid still stands:

" Wanna HEAR that taped conversation with me you say

DOES NOT exist ??

Wanna actually HEAR it - you brain dead ARSEHOLE ??

Want the Australian Federal Police to * KNOW* you publicly directed folk to
commit a murder here on this NG ?

I have a copy of the actual post.

Want that ??

Lemme know. "




....... Phil

[John Byrns]

In article ,
Patrick Turner wrote:

Emitter resistors are used in many SS amps as local
applications of series current NFB to linearize the otherwise appalling
voltage linearity
of BJTs. They also raise the effective base input resistance,
appallingly
low without such NFB.
These local NFB apps ARE local LOOP FB.
Do not try to evade the issue that it is impossible to build
a listenable bjt amp without loop NFB of some kind, or external NFB of
any kind.

NOW READ ME CAREFULLY, ARNY, A TYPICAL 6SN7 DOES NOT NEED ITS CATHODE
RESISTOR TO BE UNBYPASSED
TO PROVIDE LINEARISING LOCAL NFB, YOU GOT IT!!?

Patrick, you need to think outside the box a bit. It should be possible
to build a reasonably low distortion BJT amplifier stage by using a
current mirror type of structure. For example take 11 identical BJts
and connect 10 of them in parallel. Ground the emitter of this
composite transistor and feed the input, and bias, to the base through a
10k resistor. Connect another 10k resistor between the collector of the
composite transistor and the power supply voltage, taking the output
from the junction of the collector and the second 10k resistor. Finally
take the 11th transistor and connect its emitter to ground like the
other 10 transistors, then connect its base and collector leads together
and connect them to the base of the composite transistor made up from
the first 10 transistors. For best results over temperature these 11
transistors should ideally be built on a single silicon substrate, this
could be packaged like an ordinary transistor with only three leads. A
clever guy like you can probably get this idea to work reasonably well
with discrete transistors and a few extra components.

I can hear your objection to this circuit already, you will point out
that the eleventh transistor has feedback applied from its collector to
its base. However I don't feel this objection is valid for two reasons.
First there is no loop feedback or series current feedback applied the
main amplifying BJT. Secondly the eleventh transistor is used as a two
terminal device which is essentially a black box, theoretically this
could be replaced another two terminal device producing the same V-I
curve and not using negative feedback in its operation.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Patrick Turner]

Phil wrote:

Patrick Turner wrote:


It seems to me Cheever tries to show that the ears will produce harmonic
voltages from the
hairs in the cochlea in your ear when a pure tone is used as a signal.
The brain he says, filters out the harmonics, and we hear the tone as
pure.

To me this defies common sense, because it implies the brain would do a
lot of filtering
with music or noise which is riddled with many harmonics.
Humans are notoriously erroneous creatures. God isn't perfect, let alone
understandable,
if we take a look at his creations over the millions of years or trial
and error.

But if Cheever is correct, and the brain does away with much of what the
ear microphones feed to it
then its easy to see how MP3 formatted sound gets away with it...

Our knowledge of how things work often leads, incorrectly, to
conclusions like, the "mind" turns the image on our retina around so
that we don't see the world "upside down." However, as infants, nothing
"told our brain" which side of our retina was up or down, so it simply
learned to perceive the world, correctly, when images of the sky landed
on what we KNOW, as adults, is the bottom of the retina. In the case of
pure tones, the ear sends a signal to the brain that includes harmonics,
but to our brain, that's what a pure tone sounds like! When we hear an
"impure" tone, our ears send different signals to the brain, and we hear
a difference, with no need -- and for that matter no way -- to "filter
out" the harmonics. Having never received a pure sine wave signal from
our ears, how would our brain "know" how to filter out anything? And why
would it want to? Is there a business where a company can brag that
"this brain filters out 99% of the ear's harmonics!"

Survival of the genes is a strong instinctive motivator.

Every natural urge is related to survival, and if brains filter audio
from the ears to get
a faster message with more meaning, then you know why; hearing something
quick leads to getting first
in a competitive world, so one learns to ignore noise, and probably
distortions.

But exactly how all that happens isn't my field of expertise and I ain't
an audiologist.
But I know the mechanism of hearing is complex, and unable to be
understood easily.
and exactly what happens to electrical nerve signals leaving the ear and
travelling to the brain
is quite beyond me.

But I'd suggest that just as many people have rather obviously variable
physiology,
they also have rather varying brain function and each sense we have
varies in ability
to the next person along.

I don't reject your assessment of what may happen in ppls heads above,
but it
would be hard for me to accept it all as text book knowledge either.

Cheever seems to say that harmonic nerve voltages are generated around a
pure tone that arrives at the ear.
The brain filters out the harmonics, and we know a pure tone when we
hear one,
or put it this way, when THD exceeds roughly 0.5% of 2H, we find the
impurity to be perceptible
in the middle of a scene where the brain has decided a tone is pure
after filtering out
ear generated harmonics.
So what tells a brain to do the filtering? some sort of FB network?

If Cheever is correct,( and he may well be complete ******** if some one
can proove it, )
then would you not think that the variablity in ppl's hearing would make
them
prone to picking up much varying threshold levels of THD?

So different blends of harmonics would be created in different
ppl's ears and filtered out variably in different brains.

I could never accept that ONE generic array of harmonics is generated by
all ppl.

Hence it would seem very difficult to use Cheever's TAD method
calibrated for
everyone, but suitable perhaps to no individual.

Where does he offer a ready made set of steps 1 to 10 to apply
to make amplifiers and transducers more faithfully present audio to our
brains?

For theories to be useful, they need to be applicable.

Some guys sitting around in cafes in 1933 were well on the way to
drawing up a future on table napkins for a world based on digital
information
transfer. But they saw many insurmountable obstacles that would delay
digital until about
1970, when fast large reliable devices became viable to make and use for
civilian productivity gains,
not just for appallingly wasteful and expensive military superiority.
BJTs were just terrific if left alone in vast numbers to count things,
1,00,1,1,1,00,00,1, and so on. Using tubes for this was stupid.


In other words, we forget that as infants, our brain ADAPTED to whatever
signals our senses sent it, and those signals became standard, normal.
However, the idea that our brains ALWAYS hear harmonics makes it easier
to understand why harmonics don't bother people that much; instead of
hearing the difference between 0% and 5% THD, the signals to our brains
vary from, say, 5% to 7.2% THD (I think THD adds in an RMS manner, hence
the change of 7.2% instead of 10%), obviously a much less drastic change!

And certain blends of harmonics have very different effects on us.
Related harmonics are what substantiate music, with a few bashes and
bangs and thumps added for
rythym, which sets the pulse racing, and makes the ladies hot to trot.
Music leads to dancing, and certainly drinking, then dancing leads to
inevitable sexual passions which overcome the fears of responsiblities,
and sex is had,
and love is a trip of falling helplessly, this is being human, and
reproducing.
But we spend many years away from being sexual, and we have spare time,
and some of us are
incredibly gifted with a sense of music that seems to come from nowhere,
but makes heroes
of people like Bach, Beethoven, Motzart, and many others, whose
arrangements of harmonics summon
up all sorts of deeper complex emotions well away from the simple
tom-tom
thrub of popular music and its primitive sexual dis-inhibitor function.

Pure tones are seldom heard in the natural world of sounds.
But occasionally somone pulls out a complex silver plated flute from a
leather bound case and we have
fairly pure tones, and we know it. Its magic. But where a japanese
master
reaches for his shakuhachi flute we know immediately what it is, and
isn't.
More magic.

Now if the sound of such instruments were to have the signature sound of
crossover distortions added to them,
many would hear the flutes as somewhat spoiled perhaps, and perhaps the
tiny % of SS crossover harmonics are much more
UNATURAL than the much greater added harmonics of the class A SET
amplifer.
Look how easy it is for so many ppl to so easily hear someone play a
slightly off key note.
If ppl have been to a primary school concert, there will be plenty of
off key events,
then less as the students become faster at adjusting frequencies
produced to match those around them.
off key need only be a few cycles per second, but we notice it severely.
One does not need to much 7H harmonic to be added into a C chord to make
the sound bad.
Of course we grow use to some harsh blends of harmonics. A saxaphone has
a very awkward blend.
Tom Waits tries to sing, and barely manages, but ppl buy his voice.

So ears and brains are extremely fickle in what they like or don't like.


After a brief glance, it LOOKS like a good paper, the result of honest,
intelligent research, one worth using in amp design until either

(1) you
find a better paper,

I keep an eye open even while i sleep. One never knows where some truth
may lie.
It's strange to say that truth lies, but initially it seems like it,
until we accept it.
Cheever's ideas seem to have no practical application, although probably
there is some truth somewhere in at least some of what he says about
brain interpretations of sound.

I am human, and have only my experience to guide me, and this includes
the
feedback i get from my clients for whom I have built amplifiers,
or occasionally built speakers, or re-engineered existing audio gear.

The present status quo of adhering to some pretty basic rules
such as maintaining 20hz to 20kHz BW, low THD/IMD at loud normal
listening levels,
low noise, and low amp resistance is not foolish, and leads to more
successes,
and few failures I can recall.

Intermodulation products are IMHO, the very worst products that can
become added to any audio signal.
THD is not itself a worry, since so many harmonics are present in music
that altering their relative levels
by a percent or two makes no detectable tonal change.
But IMD action whose cause relates to the device non liearity expressed
by THD numbers
creates the sum and difference frequencies created between every pair of
frequencies
to a mush of distracting noise unless limited to low levels prefereably
below 0.1%.
This is based on a simple standard 60+ year old test of using 4V of 80Hz
and 1V
of 5kHz, and the 5,080hz and 4,820Hz IMD tones created should together
be less than 0.1% of the 5kHz amplitude.
Its easier than you may think to measure this.

Its my belief that the amount and complexity of IMD created in tube amps
is more forgivable
that that found in many (but not all) solid state amps, ie, you can have
far higher measured IMD in a tube amp
than you can in an SS amp and get away with it without ppl condemning
the tube amp
as rough, harsh and hard sounding.
Natural intermodulation F are produced within instruments, and perhaps
tube amp mimic
instruments, and hence are more acceptable.
To limit IMD of SS amps, I believe they need all the NFB they can
muster, unless they are set up
in class A, and suddenly ppl find that a class A pair of mosfets need no
more NFB than a
pair of class A KT66 in a Quad-II.
I have tested this idea by secretly swapping a beautiful 50 watt class A
tube amp for a
300 watt mosfet based amp with a zillion dB of total NFB and the
gathered audiophiles never noticed, and when i said I had swapped over a
major component,
they couldn't pick what it may have been, and when told, and when i
switched back and forth
the differences could not be heard.
Both the SS amd tube amps cost about the same to make and weighed about
the same,
and had the same designer, as one dude later told me, so maybe this
explained the simularity in performances.
It was indeed a rare and enjoyable evening.
The tube amp had 0.02% THD and SS amp about 0.002% at levels used for
the evening.

This was one of my very real guiding experiences.

I can entertain Cheever's ideas. I am not threatened, my world has not
been made invalid,
I know what works, and a lot of what does not. Perhaps i can learn
something new, i hope,
some of the time.


Oustide my simple recipe which is achieved with science, discipline,
careful measurements,
and attention to natural simple linearity, almost anything goes, like
changing cables, capacitors, and
using Skakti stones on speakers. Things within the "anything goes"
department don't interest me much,
and I don't believe they make much difference, but if quackery in audio
leads people to better enjoy
the musical experience and with a passion at home then so be it, at
least they seem to know what does make them at peace,
while others seem not at peace, on the warpath, and worried excessively
about
meters and numbers.

My "better paper" is written here and in my website for all to read.

Lord knows what Mr Cheever would say if he read it.


(2) you find various tricks and techniques that
add to and/or improve upon the techniques he proposes.


Exactly, one can always build upon foundations laid by others.
Its almost completely impossible to be totally original in any field of
human endeavour
or interest, we as a species are becoming more connected each day and
more interactive,
and despite the protestations of the Chinese People's Communist Party
and the
Iranian Goverment's objections to the operation of the FREE Internet.
All these old world hegemonic old power huggers
will be swept asside in future, and advances made where some seemed
impossible.
It may of course doom us even sooner rather than later, because if the
all the worlds'
9 billion people in 20 years all want to live like little kings and
queens then we can only
wonder how the planet can afford ans sustain it all for countless future
generations.

But I digress. I rather admire Peter Walker's Quad II amplifier topology
for
output stages. It is foundational for me. I build amps with a similar
topology.
But I don't use pentode driver stages unless strapped as triodes,
because the pentode
has far worse distortion spectra than triodes, and a greater amount of
them.
So to use an EL84 as a driver tube in pentode mode it needs its own
local shunt loop NFB
to reduce pentode gain from a maxima of around 200 to 20 to make it as
linear as triode,
and even then the spectra is just the same as pentode but reduced, and
not as simple as triode strapping.
I like the EL84 used as a triode driver because it seems to make the
sound from
any following stage more dynamic. It should, the EL84 in triode is about
equal to having
5 halves of a 6SN7 in parallel, and just as linear.


However, i still have a few ideas to try, and it is to be remembered
that
pentodes at low levels have been considered no worse sounding in much
audio gear of the past,
including where Quad and Leak et all used EF86.
Andy Grove continued the pentode tradition in Quad 40 amps with the use
of 6SH7 pentodes
instead of EF86.
There are millions of EF80/6BX6 anhd 6EJ7/EF184 left in the world, none
are darlings of the
hi-fi cognescenti but what would they know? have they built any amps?
Do they ever solder anything?
Using EF86 or much more gutsy 6BX6 or 6EJ7 the same way can have similar
problems,
or similar benefits.....

I have not tried the local shunt NFB idea around the EL84 pentode as a
driver stage.
Its extra circuitry, and its giving in to the idea that yet more devices
solve a problem,
but maybe it just won't. Conrad Jonson and ARC and a perhaps McIntosh
have allowed their circuits to become probably too complex for the music
to survive optimally.
These amps seem to me like are monuments to designer cleverness with
numbers rather than
symbols of effective simplicity.


I am not sure i want to lay waste the Cheever empire to leave
bloodstained foundations
amidst ashes of his thoughts, but if his temple is wood, and rots with
age,
maybe I would build a firmer stonework ediface where people could
worship without regrets or guilt.

Surely this would be a more harmonious outcome.

Patrick Turner.



Phil

[Ian Bell]

Patrick Turner wrote:



Ian Bell wrote:

Patrick Turner wrote:

Without any NFB whatsoever, local or loop current current or voltage, a
BJT amp has perhaps 10% THD.

Just try connecting up ONE lone BC546, use a basic common emitter gain
stage with resistor collector load
and 30V supply, so that the collector idles at 15Vdc.
Make sure you have ZERO emitter resistance included, or if you must
have an emitter resistor,
bypass it with 1,000uF, to ensure there is no ac NFB present.
Measure the THD with a sine wave at 9Vrms output.

When you have done this experiment, talk to me about BJT linearity.


That test is a trifle unfair as you are asking the BJT to swing 25V from
a 30V supply.

When did I ever say try to swing 25Vrms????


You didn't - you said 9V rms which is 25V peak to peak. I was just
suggesting asking a BJT to swing 25V with a 30V supply is a little harsh,
that's all.

if you have a +30V supply, with Ec at +15V, then all you would get is
+/- 12V peak approximately,
or around 9Vrms, which is what I recall I said.


Indeed it does, but it rather limits the biasing options. Surely you won't
begrudge ma another 30V to play with?


However I have set up a circuit with a single BJT, no NFB, 60V
rail. 2nd harmonic is 36dB down i.e just over 1.5%. Higher harmonics are
progressively lower. Nowhere near the 10% you mentioned.

All the bjts I have tested go an awful lot worse than you say.

They are disgustingly non linear.


As I've told you before, BJTs prefer a current input. It is simply a matter
of proper design.


Probably you have an emitter resistor which you have not bypassed to
avoid the local NFB.


I do have an emitter resistor, but it is bypassed by 10000uF, just for you
Patrick.

Please present your schematic and post it to your home page for all to
see with
all operating voltages. We'd all sure like to duplicate your experiment
to verify your claims.


No problem. See the the SwitcherCAD file below:


----------------------------------------------
Version 4
SHEET 1 880 680
WIRE 112 32 -32 32
WIRE 400 32 112 32
WIRE -32 64 -32 32
WIRE 112 64 112 32
WIRE 400 64 400 32
WIRE 112 192 112 144
WIRE 176 192 112 192
WIRE 320 192 240 192
WIRE 112 240 112 192
WIRE -192 272 -240 272
WIRE -48 272 -128 272
WIRE -32 272 -32 144
WIRE -32 272 -48 272
WIRE -32 288 -32 272
WIRE -240 368 -240 272
WIRE -48 368 -48 272
WIRE 112 368 112 336
WIRE 192 368 112 368
WIRE 320 368 320 192
WIRE 112 384 112 368
WIRE 192 384 192 368
WIRE -240 512 -240 448
WIRE -48 512 -48 448
WIRE -48 512 -240 512
WIRE 112 512 112 464
WIRE 112 512 -48 512
WIRE 192 512 192 448
WIRE 192 512 112 512
WIRE 224 512 192 512
WIRE 320 512 320 448
WIRE 320 512 224 512
WIRE 400 512 400 144
WIRE 400 512 320 512
FLAG 224 512 0
FLAG 320 192 out
SYMBOL npn 48 240 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL res 96 48 R0
SYMATTR InstName R1
SYMATTR Value 50K
SYMBOL res 96 368 R0
SYMATTR InstName R2
SYMATTR Value 1K
SYMBOL res -48 48 R0
SYMATTR InstName R3
SYMATTR Value 590K
SYMBOL res -64 352 R0
SYMATTR InstName R4
SYMATTR Value 15K
SYMBOL cap -128 256 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C2
SYMATTR Value 10µF
SYMBOL voltage -240 352 R0
WINDOW 123 24 132 Left 0
WINDOW 39 24 160 Left 0
SYMATTR Value2 AC 0.001
SYMATTR SpiceLine Rser=150
SYMATTR InstName V1
SYMATTR Value SINE(0 70mV 1000)
SYMBOL voltage 400 48 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 60V
SYMBOL cap 176 384 R0
SYMATTR InstName C3
SYMATTR Value 10000µF
SYMBOL cap 240 176 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C1
SYMATTR Value 10µF
SYMBOL res 304 352 R0
SYMATTR InstName R5
SYMATTR Value 50K
SYMBOL res 64 272 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R6
SYMATTR Value 30K
TEXT -192 136 Left 0 !.tran 0 2 1.5 10uS
TEXT -192 160 Left 0 !;op
---------------------------------

Enjoy,

Ian

[Arny Krueger]

"Ian Bell" wrote in message
news:46000d0d.0@entanet
Patrick Turner wrote:

Ian Bell wrote:

Patrick Turner wrote:

All the bjts I have tested go an awful lot worse than
you say.

They are disgustingly non linear.

As I've told you before, BJTs prefer a current input. It
is simply a matter of proper design.

This is the crux of the problem. As a debating trade tactic, Turner rants
and raves about the nonlinearity of BJTs, which is true if they are used as
if they are tubes other than cathode followers. Use BJTs in accordance with
accepted practice for the past 40 or more years, or use them like tubes in
cathode followers, and they are plenty linear.

Bottom line is that by excluding enough perfectly accepted and common
operating circumstances, Turner can deceive naive true believers. Not
informed true believers, just naive ones. Now you know who Turner markets
to.

[Iain Churches]

"Sander deWaal" wrote in message
...
"Arny Krueger" said:


Typical of Sander's overly-confrontational approach to technology he can't
properly understand.


ROFL!!

That's why I design amps for a living, and you fix computers and work
on your "usenet career", hmmm? ;-)

--

Sander. I had a very similar confrontation with Arny on the subject of
classical music recording (which it what I do for a living) Discussion
regarding our relative skills ended abruptly when someone sent me
one of Arny's choir recording efforts. I did not know whether to
laugh or cry, and have not been able to take him seriously since
that moment.

I am sure he is very good at fixing second hand computers though
(but then so is my ten-year old nephew)

It would be interesting to see some of Arny's hombrew tube amps.
Hopefully he will post a link.

Iain

[Iain Churches]

"Arny Krueger" wrote in message
. ..
"Patrick Turner" wrote in message


Perhaps Arny has never ever built a tube amp
successfully.

I built my first tube amp from scratch some place around 1959. I ran it
for about three years until I built something better. It was successful
enough for me for about three years.

Arny. I would be interested to see a tube design you have built in the past
two years.

Iain

[Arny Krueger]

"Iain Churches" wrote in message
. fi
"Sander deWaal" wrote in message
...
"Arny Krueger" said:


Typical of Sander's overly-confrontational approach to
technology he can't properly understand.

ROFL!!

That's why I design amps for a living, and you fix
computers and work on your "usenet career", hmmm? ;-)

I find Sander's newfound self-confidence as an "amplifier designer" to be
pretty curious.

Perhaps Sander can name a store in SE Michigan that has one of his
amplifiers in stock. ;-)

Is Sander's brand name deWaal or what?

Sander. I had a very similar confrontation with Arny on
the subject of classical music recording (which it what I
do for a living) Discussion regarding our relative
skills ended abruptly when someone sent me one of Arny's choir recording
efforts. I did not know
whether to laugh or cry, and have not been able to take him
seriously since that moment.

In fact Iain has never made a recording in his life all by himself and with
resources that he himself was the sole owner of. He's always been more like
a worker on a production line. He has always used other people's equipment,
and with the direct assistance of other people. Nothing wrong with that,
but he confuses all of this assistance with his own productivity.

I am sure he is very good at fixing second hand computers
though (but then so is my ten-year old nephew)

Yeah sure.

It would be interesting to see some of Arny's hombrew
tube amps. Hopefully he will post a link.

Unlike Iain, I figured out that tubes were obsolete for the purpose of audio
amplification about 40 years ago. I haven't owned a tubed power amp since
then.

OTOH, I was probably my own scratch-designed tubed power amps before Iain
learned how to solder.

[Iain Churches]

"Patrick Turner" wrote in message
...

Everyone knows just how slimy Arny is, and what an arsole ****head.
Sorry Arny, but you really deserve an award for being a slimy AH.

He has one. Just a year ago he was cited as "the most coarse,
unpleasant and uncouth person on Usenet" together with his pal
Pinkerton. Now that's quite an accolade for a Born Again Christian:-)
Since then, Arny has been using mouth wash, and Pinky has disappeared.
Hopefully, Arny will do the same. He clearly has no interest in tube
audio (I am still waiting for him to post some links to his homebrews)
and his raison d'etre here is simply to disrupt this group.

[Iain Churches]

"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
. fi
"Sander deWaal" wrote in message
...
"Arny Krueger" said:


Typical of Sander's overly-confrontational approach to
technology he can't properly understand.

ROFL!!

That's why I design amps for a living, and you fix
computers and work on your "usenet career", hmmm? ;-)

I find Sander's newfound self-confidence as an "amplifier designer" to be
pretty curious.

Perhaps Sander can name a store in SE Michigan that has one of his
amplifiers in stock. ;-)

I have just been looking at some archive postings. Sander has some
really excellent posts, made in very good English, which I know is not
his first language. I can find little of relevance or value in tube audio
by Arny. Also, his command of English, which *is* his first (and
probably only) language, is lamentable.

Sander. I had a very similar confrontation with Arny on
the subject of classical music recording (which it what I
do for a living) Discussion regarding our relative
skills ended abruptly when someone sent me one of Arny's choir recording
efforts. I did not know
whether to laugh or cry, and have not been able to take him
seriously since that moment.

In fact Iain has never made a recording in his life all by himself and
with resources that he himself was the sole owner of. He's always been
more like a worker on a production line. He has always used other people's
equipment, and with the direct assistance of other people. Nothing wrong
with that, but he confuses all of this assistance with his own
productivity.

Arny, you really don't have a clue about commercial classical recording
do you? Have you any idea of the cost per minute of a symphony orchestra
and a choir of 120 highly paid professionals? It takes a well-organised and
highly skilled team of solid professionals to record such a project.
I am proud to work with such a team.


I am sure he is very good at fixing second hand computers
though (but then so is my ten-year old nephew)

Yeah sure.

It would be interesting to see some of Arny's hombrew
tube amps. Hopefully he will post a link.

Unlike Iain, I figured out that tubes were obsolete for the purpose of
audio amplification about 40 years ago. I haven't owned a tubed power amp
since then.

Then why are you wasting our time here on RAT. Couldn't you/shouldn't
you be somewhere else?

OTOH, I was probably my own scratch-designed tubed power amps before Iain
learned how to solder.

:-)) Arny, you are full of wind, you should take up the Sarusaphone:-)

Iain

[Arny Krueger]

"Iain Churches" wrote in message
. fi
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
. fi
"Sander deWaal" wrote in message
...
"Arny Krueger" said:


Typical of Sander's overly-confrontational approach to
technology he can't properly understand.

ROFL!!

That's why I design amps for a living, and you fix
computers and work on your "usenet career", hmmm? ;-)

I find Sander's newfound self-confidence as an
"amplifier designer" to be pretty curious.

Perhaps Sander can name a store in SE Michigan that has
one of his amplifiers in stock. ;-)

I have just been looking at some archive postings. Sander has some really
excellent posts, made in very good English, which
I know is not his first language.

Sander often posts pretty incoherently, perhaps testimony to the effects of
the legalization of pot in the Netherlands.

I can find little of relevance or value in tube audio by Arny.

Speaks to your prejudices, Iain.

lso, his command of
English, which *is* his first (and probably only) language, is lamentable.

Iain, your mind is wandering again. The question at hand relates to Sander's
claim that he "designs amps for a living".

Sander. I had a very similar confrontation with Arny on
the subject of classical music recording (which it what
I do for a living) Discussion regarding our relative
skills ended abruptly when someone sent me one of
Arny's choir recording efforts. I did not know
whether to laugh or cry, and have not been able to
take him seriously since that moment.

In fact Iain has never made a recording in his life all
by himself and with resources that he himself was the
sole owner of. He's always been more like a worker on a
production line. He has always used other people's
equipment, and with the direct assistance of other
people. Nothing wrong with that, but he confuses all of
this assistance with his own productivity.

Arny, you really don't have a clue about commercial
classical recording do you? Have you any idea of the cost per minute of a
symphony orchestra and a choir of 120 highly paid
professionals? It takes a well-organised and highly
skilled team of solid professionals to record such a
project. I am proud to work with such a team.

IOW Iain, given a horde of minders, you can be allowed on the premises of a
recording session without things becoming too bollixed up.


It would be interesting to see some of Arny's hombrew
tube amps. Hopefully he will post a link.

Unlike Iain, I figured out that tubes were obsolete for
the purpose of audio amplification about 40 years ago. I
haven't owned a tubed power amp since then.

Then why are you wasting our time here on RAT.

Doing my part towards keeping shysters like Patrick under control.

Couldn't you/shouldn't you be somewhere else?

Through the "magic" of Usenet, Iain. Do try to catch up soon.

[Arny Krueger]

"Iain Churches" wrote in message
.fi

Just a year ago he was cited as "the most
coarse, unpleasant and uncouth person on Usenet" together with his pal
Pinkerton.

Strangly enough, no such post can be found by Google on either Usenet or the
web.

[TT]

"Phil Allison" wrote in message
...
BTW:

My earlier, personal MESSAGE to the Turneroid still
stands:

My earlier MESSAGE to you still stands!

" Wanna HEAR that taped conversation with me you say

Yep! We all do. I still offer free webspace to post it
publicly. Also use a dictionary to check the meaning of the
word "Publicly"!


DOES NOT exist ??

**CORRECT** it does not exist.


Wanna actually HEAR it - you brain dead ARSEHOLE ??

Can't hear what doesn't exist.


Want the Australian Federal Police to * KNOW* you
publicly directed folk to
commit a murder here on this NG ?

Sigh..... "Ditto"


I have a copy of the actual post.

Ditto! I refer you to your post under the heading "wanted
dead or alive."


Want that ??

Yep!


Lemme know. "

see above


...... Philthy the liar

So Quad Boy either put up or shut up! Stop your ranting,
your whining and your repetitive bull**** posts on the
matter everyone is sick to death of you and your little
hobby horse. No wonder you are unemployable!

TT (numero uno)

[atec 77]

Phil Allison wrote:
"Arny Krueger"

There' no chance of a rational discussion with someone that is as deep
into self-serving falsification and deception as you, Patrick.


** Boy, oh boy - ain't that the TRUTH.

The " Turneroid " public menace is not so named without reason.

Relates to terms like:

Android, Haemorrhoid & Mongoloid.

Cos the ASS is all of those.



BTW:

My earlier, personal MESSAGE to the Turneroid still stands:

" Wanna HEAR that taped conversation with me you say

DOES NOT exist ??

Wanna actually HEAR it - you brain dead ARSEHOLE ??

Want the Australian Federal Police to * KNOW* you publicly directed folk to
commit a murder here on this NG ?

I have a copy of the actual post.

Want that ??

Lemme know. "




...... Phil




How about you post a link to the file or if unable to find it let the
group know and I am sure some will be happy to come around and assist
Oh and philthy have a really shiite day .

[Phil Allison]

"Ian Bell"


( snip mindless ****wit abuse)


** Even if this moron's IQ were QUINTUPLED, he would still

be just another dumb****, small time pommy fader jerk.





...... Phil

[Ian Bell]

You need to find improved medical services Phil.

[Patrick Turner]

John Byrns wrote:

In article ,
Patrick Turner wrote:

Emitter resistors are used in many SS amps as local
applications of series current NFB to linearize the otherwise appalling
voltage linearity
of BJTs. They also raise the effective base input resistance,
appallingly
low without such NFB.
These local NFB apps ARE local LOOP FB.
Do not try to evade the issue that it is impossible to build
a listenable bjt amp without loop NFB of some kind, or external NFB of
any kind.

NOW READ ME CAREFULLY, ARNY, A TYPICAL 6SN7 DOES NOT NEED ITS CATHODE
RESISTOR TO BE UNBYPASSED
TO PROVIDE LINEARISING LOCAL NFB, YOU GOT IT!!?

Patrick, you need to think outside the box a bit.


John, I wake up each day telling myself to think outside the square, not
once, but twice,
and to be a good tech and to drive carefully, and not take risks on the
bicycle.
I don't have to tell myself to keep out of other troubles, those
troubles tend to avoid me....

It should be possible
to build a reasonably low distortion BJT amplifier stage by using a
current mirror type of structure.

Where is the schematic for your proposal?


For example take 11 identical BJts
and connect 10 of them in parallel.

But is this for a power application? preamp?, what?

Ground the emitter of this
composite transistor and feed the input, and bias, to the base through a
10k resistor. Connect another 10k resistor between the collector of the
composite transistor and the power supply voltage, taking the output
from the junction of the collector and the second 10k resistor. Finally
take the 11th transistor and connect its emitter to ground like the
other 10 transistors, then connect its base and collector leads together
and connect them to the base of the composite transistor made up from
the first 10 transistors. For best results over temperature these 11
transistors should ideally be built on a single silicon substrate, this
could be packaged like an ordinary transistor with only three leads. A
clever guy like you can probably get this idea to work reasonably well
with discrete transistors and a few extra components.

I can hear your objection to this circuit already, you will point out
that the eleventh transistor has feedback applied from its collector to
its base. However I don't feel this objection is valid for two reasons.
First there is no loop feedback or series current feedback applied the
main amplifying BJT. Secondly the eleventh transistor is used as a two
terminal device which is essentially a black box, theoretically this
could be replaced another two terminal device producing the same V-I
curve and not using negative feedback in its operation.

Regards,

John Byrns

OK, I think I have drawn up the schematic easily enough from what you
have said.
you have 10 parallel npn BJT in common emitter which is grounded.
Input AND bias from a low Z source is via series 10k to the 10 bases.
Output from the 10 collectors.

an 11th npn BJT is also set up with emitter grounded, but its base and
collector
both connected to the other 10 bases, so in effect the 11th BJT is a
Baxandall diode,
and for some reason you are perhaps suggesting that as the base input
voltage rises,
so does the current in the 11th BJT, as it does in the other 10 BJT, and
you'd get a linear
voltage outcome.

Have you set up a circuit and tested it? I have not.

But without the 11th BJT, I can tell you that because you have a series
10k between input voltage
and base connection, you will find the output much more linear at the
collector because the
10k makes the input into a near constant current drive, and where Iin
remains constant,
Iout will be constant.

If each of the 10BJT have Rb-in = 1k, then with 10 in parallel, you have
Rin total at the paralleled bases
of only 100 ohms, so if you have 10V at the input source, with 10k in
series the base voltage will be only
0.01V, and if the gm of the BJTs is say 6A/V, a typical value for 10
parallel
BC546, then the output voltage at the 10k collector load could be
60Vrms, so between
source and collector output, you'd have voltage gain = 6.

Since any distortion current in the load and collector circuit causes a
base current = Ic / hfe,
then you have a shunt NFB collector network in action.

All my posts on the Internet so far which have always denigrated BJTs as
being very non linear voltage
amps remain correct.

All my posts pointing out this **** poor BJT VOLTAGE linearity
are based on having

****ZERO CURRENT NFB AND ZERO VOLTAGE NFB ANYWHERE ANYPLACE, ANY TIME
ANYWHERE NEAR THE BLOOMIN BJT. NO LOCAL, NO GLOBAL, NIL, NONE, NOT
PRESENT, OK.****

I hope I make myself clear. I am SICK AND TIRED of all these people
coming along
to tell me how linear BJTs are without NFB and then when they challenge
me with
a story about how linear a BJT test they ALLEGEDLY say they have done,
and i ask them immediately for a schematic,
and test conditions, and try to be factual and scientific, but alas they
ARE USING SOME ****ING NFB somewhere.

All these lazy sons of bitches won't conduct experiments to find out
anything
real themselves, and do not want to admit their favourite devices need
NFB to make them linear.

But John, you don't need to have 10 parallel BJTs to begin with now do
you?

What was the purpose of having 10? it won't improove linearity one bit
as i see it.
( and you wouldn't need to parallel 10 x 6SN7 to proove how linear they
can be now would you? )

The VOLTAGE linearity of a BJT can be measured as follows :-

Set up a SINGLE BC546 or similar type in common emitter, grounded, in a
simple gain stage, with 10k collector load to B+
of +40V.
Have a lowZ bias supply with 10k feed taken to the base, and adjust the
bias V to some +ve level
to make collector idle Vdc = +20V, so there is 2mA of Ic and IRL.

Connect 1,000uF cap to the base and feed in an input voltage from a
LINEAR source with source Z less than 10 ohms.
This can be from a known linear power amp and via a resistance divider.
The input resistance of a BJT is so low it will invalidate measurements
and observations if
the source resistance of the input test signal is not a lot lower than
the BJT base input resistance.

Using a signal of 400Hz, adjust the input voltage level to give an
output signal level of 2Vrms.

Voltage gain = Vout/Vin = Vc/Vb. Its possible that voltage gain will be
quite high, perhaps 1,000.
You may find that only 0.002Vrms is needed at the base to give the 2Vrms
at the collector.

With 2V of signal output, linearity can be easily checked with a
distortion meter and monitored with a CRO.

The collector output maximum will probably be +/-17Vpk, or about 12Vrms.
The THD% can be plotted for all output voltages between 0.5Vrms and
12Vrms, and a graph drawn.

We know the input voltage IS LINEAR. We know there is NO NFB anywhere.

We WILL KNOW just what a poor voltage amp the BJT is when compared to
almost anything else
under the conditions of ZERO NFB.

I suggest all you group members conduct this simple test tonight in your
workshops
and let me know tommorrow what the results are.

But If I do not hear from any of you with results of having done the
tests then
I will assume you know nothing about transistors.

If anyone wants to convince anyone else they know about something, they
need to work to proove they do.

I have no regrets about being terse, impolite, hostile, tactless,
arrogant, pig-headed,
and downright contemptuous of ANYONE who fails to do his home work but
who gets up
in the pulpit and preaches at me with a stream of utter BS which has no
foundation of
observed facts about electronic device behaviours.

Better teachers than myself EARNED my respect.

Patrick Turner.

[Patrick Turner]

Ian Bell wrote:

Patrick Turner wrote:



Ian Bell wrote:

Patrick Turner wrote:

Without any NFB whatsoever, local or loop current current or voltage, a
BJT amp has perhaps 10% THD.

Just try connecting up ONE lone BC546, use a basic common emitter gain
stage with resistor collector load
and 30V supply, so that the collector idles at 15Vdc.
Make sure you have ZERO emitter resistance included, or if you must
have an emitter resistor,
bypass it with 1,000uF, to ensure there is no ac NFB present.
Measure the THD with a sine wave at 9Vrms output.

When you have done this experiment, talk to me about BJT linearity.


That test is a trifle unfair as you are asking the BJT to swing 25V from
a 30V supply.

When did I ever say try to swing 25Vrms????


You didn't - you said 9V rms which is 25V peak to peak. I was just
suggesting asking a BJT to swing 25V with a 30V supply is a little harsh,
that's all.

Always be specific.

It avoids confusion. I try to make ALL my messages mean only ONE thing.
25V could be anything.
9Vrms is an official scientific way to describe an ac voltage reading
where pk to pk is indeed near 25V.

9Vrms output from a BJT set up with a +30V single rail supply is about
what should expect.
There is nothing harsh about it, although without a shirtload of NFB,
the sound
quality could be quite harsh; is that what you meant?


if you have a +30V supply, with Ec at +15V, then all you would get is
+/- 12V peak approximately,
or around 9Vrms, which is what I recall I said.


Indeed it does, but it rather limits the biasing options. Surely you won't
begrudge ma another 30V to play with?


However I have set up a circuit with a single BJT, no NFB, 60V
rail. 2nd harmonic is 36dB down i.e just over 1.5%. Higher harmonics are
progressively lower. Nowhere near the 10% you mentioned.

All the bjts I have tested go an awful lot worse than you say.

They are disgustingly non linear.


As I've told you before, BJTs prefer a current input. It is simply a matter
of proper design.


Probably you have an emitter resistor which you have not bypassed to
avoid the local NFB.


I do have an emitter resistor, but it is bypassed by 10000uF, just for you
Patrick.

Please present your schematic and post it to your home page for all to
see with
all operating voltages. We'd all sure like to duplicate your experiment
to verify your claims.


No problem. See the the SwitcherCAD file below:

A real schematic is one that you have drawn up from what you have built
on your breadboard.

Real distortion is what you measured with a meter, and monitored with a
CRO.

I am ONLY interested in REALITY.

You need to work harder to convince me of something here.
Don't forget all the other guys, they are watching you as well.

Patrick Turner.



----------------------------------------------
Version 4
SHEET 1 880 680
WIRE 112 32 -32 32
WIRE 400 32 112 32
WIRE -32 64 -32 32
WIRE 112 64 112 32
WIRE 400 64 400 32
WIRE 112 192 112 144
WIRE 176 192 112 192
WIRE 320 192 240 192
WIRE 112 240 112 192
WIRE -192 272 -240 272
WIRE -48 272 -128 272
WIRE -32 272 -32 144
WIRE -32 272 -48 272
WIRE -32 288 -32 272
WIRE -240 368 -240 272
WIRE -48 368 -48 272
WIRE 112 368 112 336
WIRE 192 368 112 368
WIRE 320 368 320 192
WIRE 112 384 112 368
WIRE 192 384 192 368
WIRE -240 512 -240 448
WIRE -48 512 -48 448
WIRE -48 512 -240 512
WIRE 112 512 112 464
WIRE 112 512 -48 512
WIRE 192 512 192 448
WIRE 192 512 112 512
WIRE 224 512 192 512
WIRE 320 512 320 448
WIRE 320 512 224 512
WIRE 400 512 400 144
WIRE 400 512 320 512
FLAG 224 512 0
FLAG 320 192 out
SYMBOL npn 48 240 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL res 96 48 R0
SYMATTR InstName R1
SYMATTR Value 50K
SYMBOL res 96 368 R0
SYMATTR InstName R2
SYMATTR Value 1K
SYMBOL res -48 48 R0
SYMATTR InstName R3
SYMATTR Value 590K
SYMBOL res -64 352 R0
SYMATTR InstName R4
SYMATTR Value 15K
SYMBOL cap -128 256 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C2
SYMATTR Value 10µF
SYMBOL voltage -240 352 R0
WINDOW 123 24 132 Left 0
WINDOW 39 24 160 Left 0
SYMATTR Value2 AC 0.001
SYMATTR SpiceLine Rser=150
SYMATTR InstName V1
SYMATTR Value SINE(0 70mV 1000)
SYMBOL voltage 400 48 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 60V
SYMBOL cap 176 384 R0
SYMATTR InstName C3
SYMATTR Value 10000µF
SYMBOL cap 240 176 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C1
SYMATTR Value 10µF
SYMBOL res 304 352 R0
SYMATTR InstName R5
SYMATTR Value 50K
SYMBOL res 64 272 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R6
SYMATTR Value 30K
TEXT -192 136 Left 0 !.tran 0 2 1.5 10uS
TEXT -192 160 Left 0 !;op
---------------------------------

Enjoy,

Ian

[Eiron]

Patrick Turner wrote:

The VOLTAGE linearity of a BJT can be measured as follows :-

Set up a SINGLE BC546 or similar type in common emitter, grounded, in a
simple gain stage, with 10k collector load to B+
of +40V.
Have a lowZ bias supply with 10k feed taken to the base, and adjust the
bias V to some +ve level
to make collector idle Vdc = +20V, so there is 2mA of Ic and IRL.

Connect 1,000uF cap to the base and feed in an input voltage from a
LINEAR source with source Z less than 10 ohms.
This can be from a known linear power amp and via a resistance divider.
The input resistance of a BJT is so low it will invalidate measurements
and observations if
the source resistance of the input test signal is not a lot lower than
the BJT base input resistance.

Using a signal of 400Hz, adjust the input voltage level to give an
output signal level of 2Vrms.

Voltage gain = Vout/Vin = Vc/Vb. Its possible that voltage gain will be
quite high, perhaps 1,000.
You may find that only 0.002Vrms is needed at the base to give the 2Vrms
at the collector.

With 2V of signal output, linearity can be easily checked with a
distortion meter and monitored with a CRO.

The collector output maximum will probably be +/-17Vpk, or about 12Vrms.
The THD% can be plotted for all output voltages between 0.5Vrms and
12Vrms, and a graph drawn.

We know the input voltage IS LINEAR. We know there is NO NFB anywhere.

We WILL KNOW just what a poor voltage amp the BJT is when compared to
almost anything else
under the conditions of ZERO NFB.

I suggest all you group members conduct this simple test tonight in your
workshops
and let me know tommorrow what the results are.

But If I do not hear from any of you with results of having done the
tests then
I will assume you know nothing about transistors.


Some of us have jobs so can't spare the time to do experiments we last did
in school but of course your circuit will be non-linear. On the other hand,
that is a circuit that nobody would ever build unless they wanted to
make an amp that sounds like a SET. So what's your point?
Why not suggest analysing a real gain stage in a real amp?

--
Eiron.

[Ian Bell]

Patrick Turner wrote:

A real schematic is one that you have drawn up from what you have built
on your breadboard.

Real distortion is what you measured with a meter, and monitored with a
CRO.

I am ONLY interested in REALITY.

You need to work harder to convince me of something here.
Don't forget all the other guys, they are watching you as well.


Really Patrick, I have absolutely no need or desire to convince you of
anything. If you won't take my word for it, build the circuit I provided
and measure it yourself as I have many times in the past. As for the
SwitchCAD file, it is an excellent simulation package which produces
results that are very close to lab measurements and this one is no
exception. It was simply a convenient means to send you a design you could
check without having to build it yourself or take my word for it. But if
you don't think simulations are at all accurate then I can help you no
further. You can substitute just about any BJT in this circuit and obtain
almost identical results. I know this circuit produces the stated levels of
distortion as well as you know a triode has internal NFB.

Ian

[Patrick Turner]

Eiron wrote:

Patrick Turner wrote:

The VOLTAGE linearity of a BJT can be measured as follows :-

Set up a SINGLE BC546 or similar type in common emitter, grounded, in a
simple gain stage, with 10k collector load to B+
of +40V.
Have a lowZ bias supply with 10k feed taken to the base, and adjust the
bias V to some +ve level
to make collector idle Vdc = +20V, so there is 2mA of Ic and IRL.

Connect 1,000uF cap to the base and feed in an input voltage from a
LINEAR source with source Z less than 10 ohms.
This can be from a known linear power amp and via a resistance divider.
The input resistance of a BJT is so low it will invalidate measurements
and observations if
the source resistance of the input test signal is not a lot lower than
the BJT base input resistance.

Using a signal of 400Hz, adjust the input voltage level to give an
output signal level of 2Vrms.

Voltage gain = Vout/Vin = Vc/Vb. Its possible that voltage gain will be
quite high, perhaps 1,000.
You may find that only 0.002Vrms is needed at the base to give the 2Vrms
at the collector.

With 2V of signal output, linearity can be easily checked with a
distortion meter and monitored with a CRO.

The collector output maximum will probably be +/-17Vpk, or about 12Vrms.
The THD% can be plotted for all output voltages between 0.5Vrms and
12Vrms, and a graph drawn.

We know the input voltage IS LINEAR. We know there is NO NFB anywhere.

We WILL KNOW just what a poor voltage amp the BJT is when compared to
almost anything else
under the conditions of ZERO NFB.

I suggest all you group members conduct this simple test tonight in your
workshops
and let me know tommorrow what the results are.

But If I do not hear from any of you with results of having done the
tests then
I will assume you know nothing about transistors.

Some of us have jobs so can't spare the time to do experiments we last did
in school but of course your circuit will be non-linear.

Many people have never done the above experiment.
Until they do they will never know much about a BJT.

On the other hand,
that is a circuit that nobody would ever build unless they wanted to
make an amp that sounds like a SET.

It will not sound like an SET.

So what's your point?
Why not suggest analysing a real gain stage in a real amp?

The point is that when ppl say BJTs are linear, they are BULLSHIITING
unless they specifify carefully EVERY TIME THEY DISCUSS A CIRCUIT
exactly what they are talking about.

The test of VOLTAGE linearity is simply for people to understand the
non linear behaviour of the basic device without ANY NFB of ANY KIND.

They can do other similar tests to establish the CURRENT linearity that
exists in most BJTs.

The TWO types of linearity are not the same and its important to
understand the
basic distinctions that must be made for a particular circuit function,
which is so often beyond most
people in news groups to ever grasp.

If you talk about how to read house plans to a knitting group, they just
won't get it, will they?
But here we have groups about hi-fi and tubes et all and so electronic
functions are relevant,
but unfortunately all are grossly misunderstood,
and used to blatently and idiotically to support whatever damn fool
bull**** notion someone puts up.

When you stupidly say a bjt will sound like an SET, where is ANY
qualification for the type
of SET, where it is used, what function, and what NFB?

Same goes for a BJT. It can be compared to anything else, but you have
to say under what circumstances
to draw any relevance or meaning useful to anyone..

Anything less is UTTER BULL****.

There are no simplistic generic valid statements about electronic
circuits or devices.

SS = bad, SET = good is a simple stupid example; the condition of use
for the hardware
must be spelled out, every time.

I would have liked to think your intelligence allowed
you to see the point I have been trying to make repeatedly all along,
but alas it must be spelled out, and spoon fed.

Patrick Turner.


Eiron.

[KeithR]

Doug Flynn wrote:

Here's what I think:

Pentodes = evil
Global negative feedback = the spawn of Satan
Digitial = the work of the Devil


Pentodes, triodes, and tetrodes = products of the stone age and should be
confined to archaeological digs

Global negative feedback = the first glimmering of hope back in the dark
ages

Digitial = The only way to fly, but setting standards by trying to cram
the longest piece of music available into 640 megs was a bad
idea, mp3s - even worse.

[KeithR]

Patrick Turner wrote:

Everyone knows just how slimy Arny is, and what an arsole ****head.
Sorry Arny, but you really deserve an award for being a slimy AH.

Again Slimy Arsole lies again.

You are the net's greatest arsole who quickly resorts to telling tales
of BULL**** about what people said, or didn't say.


err, weren't you the one complaining about how Fill goes off when
criticised?

[KeithR]

Patrick Turner wrote:


And in addition to what i said below, there was a brilliant series of
articles
in the 1978-1979 copies of monthly Wireless World on the way in which
low levels
of NFB can make the sound worse.
It was penned by one Peter Baxandall, his part 6 article appears in
Feb'79,
and has very similar graphs of the NFB effects on THD spectra as Mr
Cheever
has drawn, except that Baxandall's efforts look more plausible.
The math involved are at a level fit only for a masochist with lots of
time,
but Baxandall does manage to get the point across regarding applying NFB
and its effect on spectra in THD.
To avoid the worst of what Baxandall and Cheever are saying, it would
seem prudent to
ensuring open loop distortions before NFB is applied be kept well below
the
10% level they use in the examples for their analysis.

Thats kind of interesting, I worked at the same establishment as Peter J in
the early 60s (I was an apprentice, he was THE senior circuit design
consultant). I met him on several occasions and went to a number of his
lectures. At that time he considered a good level of NFB to be essential,
his design for 10 watt EL84 amp published in Wireless World at the time
demonstrated this.

The advice that he gave then was to not bother too much about the amp, NFB
could get the THD low enough not to matter, put very big reservoir
capacitors in the PS to avoid power line droop on peaks (he was an organ
music fan), spend as much as you can on the cartridge and speaker (this was
mono days) because that is where most of your distortion is going to come
from.

Maybe he had a change of heart in his latter days, but when I knew him, the
application of NFB was the heart of his work.

[John Byrns]

In article ,
Patrick Turner wrote:

John Byrns wrote:

In article ,
Patrick Turner wrote:

I think I prefer the sound of the radio stations that have NFB built
into their carrier modulators,
so that at the station a receiver module produces audio from the
radiated RF signal,
then compares that with the audio used to modulate the RF signal, and
applies an error signal to reduce
N&D to sub audible levels.
I am wondering if I would like the whole transmission done without any
loop FB,

Did you actually check out what sorts of "carrier modulators" the
various radio stations were actually using, so that you can truthfully
say you have correlated the sound of the stations with the "carrier
modulators" they used? It's probably too late to do this experiment
today, what with digital modulation schemes having taken over the field.
Assuming that you actually investigated what sort of "carrier
modulators" were being used by the stations you preferred, as well as
those you didn't, how did you eliminate the possibility that it wasn't
the overall loop negative feedback that produced the sound you liked,
but was some other factor common to the transmitters using overall loop
negative feedback? I can think of one factor that is common to most
analog transmitters that didn't use overall loop negative feedback, i.e.
demodulated RF, that I suspect was more likely to have contributed to
your dislike of them.

What i do know is that for present AM and FM transmissions in Oz the
waves must remain compatible for existing analog receivers to
decode audio from the RF carrier waves, and the recovered audio cannot
be more linear than the transmitter modulator permits,
and so I have assumed modulators have inbuilt means to use NFB to
ensure modulation is as linear as possible. Engineers have told me but
I admit I have not seen ths latest transmitters' schematics and analysed
them.

The "Digital" AM transmitters I was speaking of were not the so called
"Digital Radio" types. What I was talking about were AM transmitters
that use digital techniques to produce an analog waveform "compatible
for existing analog receivers to decode audio from the RF carrier
waves". These are essentially large high power RF D to A converters,
that take a digital audio input from an A to D converter, CD player, or
whatever, and use it to drive the large RF D to A converter which
directly drives the antenna through a filter/matching network.

I was assuming that you were talking about the old style AM tube
transmitters. Many of these used high power class B audio amplifiers to
modulate the final RF stage in the transmitter. This type of
transmitter used negative feedback from the plates of the high power
push pull modulator tubes back to the audio input stage, this feedback
did not encompass the large modulation transformer or the modulated RF
stages. I am not aware of any transmitters of this type that apply
negative feedback around the entire transmitter from a detector
connected to the RF output. The feedback stability problems were
apparently just too great.

Many transmitters did employ loop feedback from an RF detector.
Typically transmitters of the following types used feedback from an RF
detector.

1. Low level modulation followed by high power linear amplifiers.

2. Screen modulated Tetrode final RF amplifier.

3. Low/medium level modulation followed by a triode Doherty high
efficiency linear amplifier.

4. Chireix outphasing modulation.

5. Screen modulated Tetrode Weldon Doherty high efficiency final
amplifier.

I suspect that what you were hearing was not the negative feedback of
the transmitters in the second group, but rather were the artifacts
produced by the high power class B audio stage in the first type of
transmitter.

My personal favorite is the screen modulated tetrode final with overall
negative feedback from an RF detector.

If you want to build a really low thd RF oscillator with say an AM
function
to allow between say 0% and 100% modulation levels of a tone, its not
hard to
make one up which uses NFB to linearize the modulation to an extent
where
the receiver demodulation THD/IMD will always be higher, unless
rather extraordinary measures are taken with RF and IF amplifications
and AM detection methods.

Another approach the ancients used was to start with an ordinary AM
generator that would produce the required low level of distortion at say
30% modulation, and then mix in enough out of phase carrier signal to
bring the overall modulation level up to 100%. This yields a low
distortion RF signal generator capable of low distortion at 100%
modulation. However if you push the modulation beyond 100%, this
generator does not clip the negative peaks like the common AM envelope
modulator, instead the carrier flips phase on the negative modulation
peaks, sort of like an DSB-SC modulator. The result is that an envelope
detector will show higher distortion with this type of generator when
the modulation is push past 100%, than it will with a standard AM RF
generator. On the other hand a synchronous detector will demodulate
this signal without distortion, even when it is over modulated. A
corollary of this is that if this sort of modulation scheme were used in
an actual broadcast transmitter, over modulation would not cause
sideband splatter into adjacent channels as it does with the common AM
envelope modulator.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[John Byrns]

In article ,
Patrick Turner wrote:

John Byrns wrote:

Where is the schematic for your proposal?

My scanner is broken so my verbal description will have to do.

For example take 11 identical BJts
and connect 10 of them in parallel.

But is this for a power application? preamp?, what?

I was thinking of it as a preamp, but it could be either. In fact your
mention of using it "for a power application" has got me thinking that
it might be a way to build a BJT amplifier without negative feedback for
the "Pinko" challenge. I will have to look up the ground rules for the
"Pinko" challenge, take pen, paper, and calculator in hand, and see if I
can come up with a workable solution.

[Snip]

OK, I think I have drawn up the schematic easily enough from what you
have said.

I knew you could do it.

you have 10 parallel npn BJT in common emitter which is grounded.
Input AND bias from a low Z source is via series 10k to the 10 bases.
Output from the 10 collectors.

an 11th npn BJT is also set up with emitter grounded, but its base and
collector
both connected to the other 10 bases, so in effect the 11th BJT is a
Baxandall diode,

What might I ask is a "Baxandall diode"?

and for some reason you are perhaps suggesting that as the base input
voltage rises,
so does the current in the 11th BJT, as it does in the other 10 BJT, and
you'd get a linear
voltage outcome.

Correct, but don't forget the series input resistor.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Sander deWaal]

"Arny Krueger" said:

"Sander deWaal" wrote in message

"Arny Krueger" said:

"Sander deWaal" wrote in message

John Byrns said:


The usual outcome: those who like tubes agreed with most
of it, those who loathe tubes disagreed with most of it.


Typical of Sander's overly-confrontational approach to
technology he can't properly understand.


ROFL!!

That's why I design amps for a living, and you fix
computers and work on your "usenet career", hmmm? ;-)


You design amps for a living, Sander?

Do tell!


Suffering from dementia, Arns?

http://groups.google.nl/group/rec.au...e4ae93 2cf1af
http://groups.google.nl/group/rec.au...2be909 ac1238

And meanwhile, some tube designs of my hand found their way into
production in China under the brand name "Yarland".

--

- Maggies are an addiction for life. -