[Andre Jute]

Phil Allison wrote:
"Andre Jute"


Dr Otala is a distinguished scholar and designer of highly rated audio
gear.


** Completely false.

Here is the man's CV.

http://www.kauppakorkea.fi/tutu/FUTU...nglCVotala.htm

" His specialities are Management of Change, Business Process
Re-Engineering, International Competitivity, total Quality Management, total
Quality Management, and Learning Organisations. "


The amp designs attributed to him ( for marketing purposes) were the work of
many people, unfortunately, none of them were competent audio designers.




....... Phil

That's a pretty impressive CV Otala sports, Phil. But no, I'm not
defending either Phil T's misinterpretations or even the points where
he hit the mark. I never thought he had a case, but I wanted to see his
argument in case there was something I missed or misunderstood when I
first came across these matters about 12 years ago. In fact, my opinion
has now moved on from the "amazing" in my post which set up this
collection of threads to "incredible".

I'm just kicking the usual diplomaed quarterwits in the teeth for being
netbullies and netscum, and for disgracefully failing to explain why
Phil is wrong.

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

THIS IS MY TEXT PHIL ALLISON IS REFERRING TO
Andre Jute wrote:
Phil wrote:
We're
not talking about "-30 degrees at 20 KHz," we're talking *dynamic* phase
shifting, the kind that makes a Crown preamp bite your ears off, while
testing at 0.0001% THD.

Let's hear some more about this dynamic phase shift that pours a pint
of vinegar into a Crown preamp. I'm not overimpressed with vanishign
THD but this is an amazing explanation for why so many silicon amps,
and not a few tube amps, sound like ****.

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

On the one side of this argument we have Dr Otala and Phil "Toob". Dr
Otala is a distinguished scholar and designer of highly rated audio
gear. Phil T is an earnest student who in the manner of earnest
students occasionally overstates his case.

On the other side of the argument we have Arny "I spoke in error"
Krueger and Graham "Poopie" Stevenson. Arny Krueger assembles computers
for a living and had a part in creating a now superceded and never very
useful ABX test to determine which computer sound cards did the least
damage to the sound; he pretends to be a recording engineer. Graham
Stevenson's employment appears to be writing to the Usenet about
politics and boasting about his self-proclaimed part in the design of
the least well-reputed Neve deck; when that wears thin he brags about
his education a generation ago.

From the violent attacks "I spoke in error" Krueger and Poopie
Stevenson have made on Phil T, one would be justified in concluding
that these minor players and permanent losers claim Dr Otala is simply
wrong. In fact, careful reading reveals that their entire argument is
that components have improved so much in the intervening generation as
to obviate Dr Otala's important point. The subtext of their manner of
stating this weak case is that these two loud fools are smarter than
Otala.

It is not difficult for the rest of us to decide who in a crunch we
will believe, the distinguished Dr Otala and a cross section of spec
sheets of modern components showing the problem has moved on, or the
hysterical screechings of the self-important "I spoke in error" Krueger
and his limp sidekick Poopie Stevenson.

This entire long thread has done little to illuminate my main question,
so I put it again in different form in another thread.

Andre Jute
Our legislators managed to criminalize fox-hunting and smoking; when
they will get off their collective fat arse and criminalize negative
feedback? It is clearly consumed only by undesirables.

[Arny Krueger]

"Phil" wrote in message


The "almost" part comes from
something I believe to be true, namely that the dynamic
phase shifting and other possible abuses of signals 80 dB
below the main signal in high feedback amps are *reduced*
as the speed of the closed loop increases,

This makes about as much sense as believing in the Easter Bunny.

[Phil Allison]

"Andre Jute"

Dr Otala is a distinguished scholar and designer of highly rated audio
gear.


** Completely false.

Here is the man's CV.

http://www.kauppakorkea.fi/tutu/FUTU...nglCVotala.htm

" His specialities are Management of Change, Business Process
Re-Engineering, International Competitivity, total Quality Management,
total
Quality Management, and Learning Organisations. "


The amp designs attributed to him ( for marketing purposes) were the work
of
many people, unfortunately, none of them were competent audio designers.


That's a pretty impressive CV Otala sports, Phil.


** It is a totally **apalling CV** - if the criterion is demonstrated,
audio design expertise.

Reads more like the CV for that internationally notorious audio charlatan /
con artist - Dr Amar Bose.

Otala is nothing but a pseudo-academic prick who did enormous harm with his
erroneous bunk.



I'm just kicking the usual diplomaed quarterwits in the teeth for being
netbullies and netscum, and for disgracefully failing to explain why
Phil is wrong.


** Phil T never supplied actual reasons for his wild assertions.

Only when those reasons are supplied, in sufficient detail, can they
possibly be refuted with facts.

Unsupported assertions NEED NO REFUTATION - as nothing is holding then
up.

Quoting the absent expert is a popular debating cheat, as you must be well
aware .

Phil T went several stages beyond that, with blatantly fake quotes and
alarming fallacies of his own invention.

The man is clearly a mental case.

If he were not such a conceited and malicious ASS - I might just feel
sorry for him.





........ Phil

[Phil]

Arny Krueger wrote:
"Phil" wrote in message



The "almost" part comes from
something I believe to be true, namely that the dynamic
phase shifting and other possible abuses of signals 80 dB
below the main signal in high feedback amps are *reduced*
as the speed of the closed loop increases,


This makes about as much sense as believing in the Easter Bunny.


I am truly impressed at your complete, 100% level of dishonesty. I
certainly hope anyone thinking about doing business with you takes a
look at these threads, and sees you in action. Unless they're complete
idiots, they will immediately realize that they need to do business with
almost anyone else. Your statement above implies that you believe that
higher speed devices have no advantage when it comes to feedback
problems. Right. As always, you make a general criticism with no
specifics, no references, no examples. You really are a one-note type of
guy, aren't you? The same boring debating tactic, over, and over, and
over again. Why don't you try to come up with a new form of criticism.
It can still be useless, just make it different.

Have you ever noticed that ALL the people that everyone admires have
personalities that match their true selves like a glove? And did it ever
occur to you that if you constantly treat others in ways that you cannot
stand for others to treat you, that your personality does not match your
true self (almost by definition)? People whom others admire, Arny, WORK
ON THEIR CHARACTER, every day. That means, in case you're too stupid to
get it, that they see to it that their actions toward others do not
contradict how they wish others to treat them. And now you know why you
have so few, if any, real friends, or at least, none worth having.

Phil

[George M. Middius]

Phil said:

People whom others admire, Arny, WORK
ON THEIR CHARACTER, every day. That means, in case you're too stupid to
get it, that they see to it that their actions toward others do not
contradict how they wish others to treat them. And now you know why you
have so few, if any, real friends, or at least, none worth having.

Irrelevant. Arnii is doing "God's work" on Usenet. Mr. ****'s "Usenet
career" is his pride and joy, his life's achievement, his contribution to
history. Obviously Phil you're jealous Phil of something you can never
hope to equal Phil.





--

"Christians have to ... work to make the world as loving, just, and supportive as is possible."
A. Krooger, Aug. 2006

[Arny Krueger]

"Phil" wrote in message

Arny Krueger wrote:
"Phil" wrote in message



The "almost" part comes from
something I believe to be true, namely that the dynamic
phase shifting and other possible abuses of signals 80
dB below the main signal in high feedback amps are
*reduced* as the speed of the closed loop increases,


This makes about as much sense as believing in the
Easter Bunny.
I am truly impressed at your complete, 100% level of
dishonesty.

Wrong, I'm being completely honesy about my feelings in this matter.

[paul packer]

On Sun, 10 Sep 2006 13:13:05 GMT, Phil
wrote:

This makes about as much sense as believing in the Easter Bunny.


I am truly impressed at your complete, 100% level of dishonesty. I
certainly hope anyone thinking about doing business with you takes a
look at these threads, and sees you in action. Unless they're complete
idiots, they will immediately realize that they need to do business with
almost anyone else. Your statement above implies that you believe that
higher speed devices have no advantage when it comes to feedback
problems. Right. As always, you make a general criticism with no
specifics, no references, no examples. You really are a one-note type of
guy, aren't you? The same boring debating tactic, over, and over, and
over again. Why don't you try to come up with a new form of criticism.
It can still be useless, just make it different.

Have you ever noticed that ALL the people that everyone admires have
personalities that match their true selves like a glove? And did it ever
occur to you that if you constantly treat others in ways that you cannot
stand for others to treat you, that your personality does not match your
true self (almost by definition)? People whom others admire, Arny, WORK
ON THEIR CHARACTER, every day. That means, in case you're too stupid to
get it, that they see to it that their actions toward others do not
contradict how they wish others to treat them. And now you know why you
have so few, if any, real friends, or at least, none worth having.

Phil

Wise words indeed, Phil, in every way.

[Arny Krueger]

"paul packer" wrote in message

On Sun, 10 Sep 2006 13:13:05 GMT, Phil
wrote:

This makes about as much sense as believing in the
Easter Bunny.


I am truly impressed at your complete, 100% level of
dishonesty. I certainly hope anyone thinking about doing
business with you takes a look at these threads, and
sees you in action. Unless they're complete idiots, they
will immediately realize that they need to do business
with almost anyone else. Your statement above implies
that you believe that higher speed devices have no
advantage when it comes to feedback problems. Right. As
always, you make a general criticism with no specifics,
no references, no examples. You really are a one-note
type of guy, aren't you? The same boring debating
tactic, over, and over, and over again. Why don't you
try to come up with a new form of criticism. It can
still be useless, just make it different.

Have you ever noticed that ALL the people that everyone
admires have personalities that match their true selves
like a glove? And did it ever occur to you that if you
constantly treat others in ways that you cannot stand
for others to treat you, that your personality does not
match your true self (almost by definition)? People whom
others admire, Arny, WORK ON THEIR CHARACTER, every day.
That means, in case you're too stupid to get it, that
they see to it that their actions toward others do not
contradict how they wish others to treat them. And now
you know why you have so few, if any, real friends, or
at least, none worth having.

Wise words indeed, Phil, in every way.

More evidence that Phil has one small strength - he has studied and
understood how to apply the life of P. T. Barnum.

[Arny Krueger]

"Chris Hornbeck" wrote in
message

Right. Maybe a better way for the OP to approach this is
to
begin with a true step input (a signal with *zero*
risetime) beginning at very small levels, then increasing
levels until slewing is observed.

Which may never happen.

There will be a threshold level where even an amplifier
without feedback will slew.

Not necessarily. It is entirely feasible to build an amp that never limits
due to slew rate limiting. Just limit its bandwidth.

There will also be a threshold where an amplifier *with*
feedback will slew.

Again, not necessarily.

If there are no other differences
between the amplifiers, these two levels will be *the
same*.

Or, non-existent.


For the second case, as you've said, clipping may already
have occurred. In a modern amplifier this *must* be the
case; it's too easy to get right.

Agreed.

The issue of slew-limiting in amplifiers arose because
amplifiers with feedback must sacrifice some slewing
ability to the altar of stability.

Again, not necessarily. Classic, circa-70s slew rate limiting came about
because of a dynamic range limitation that was hidden until appropriate
tests and analysis were done. Feedback didn't cause it, it only made it more
apparent if it existed.

(Many, many qualifiers need be
inserted here; whole 'nother can 'a worms. But we're
talking about a thirty year gone issue.)

Agreed.

In the early dark
days of semiconductor amplifiers, compromises for
stability were so demanding as to damage signal in the passband at
ordinary levels.

AFAIK, slew rate limiting was not a universal problem, even in the early
days.

And, FWIW, the highest rise-time possible in a
band-limited
signal is a square wave of just under bandpass frequency
run through the bandpass filter. IOW, a sinewave of the
highest frequency within the bandpass.

Agreed.

This is 101 stuff and the OP really should bone up as
possible.

Also, there's *zero, none, nada* correlation between
feedback
and anything remotely approaching "dynamic phase shift".

Agreed. Phil is just stringing together words that he doesn't seem to
understand.

The term itself is snake oil of the highest grade.

I'll argue against whether it is really high grade. ;-)

[Patrick Turner]

Phil wrote:

Arny Krueger wrote:

"Ian Iveson" wrote in
message k

Phil wrote:


Well, remember, the maximum slew rate found in audio
signals is much
greater than what a theoretical 20 KHz signal is going
to supply,

Yes and no, Phil.

Take 20kHz at full amplitude to define the required slew
rate.
Add another identical signal, in phase.

You now have twice the slew rate, as you think.

But the signal is also twice full amplitude, so it is not
comparable.
To make it comparable, you must reduce it to full
amplitude.
In so doing, you halve the slew rate, returning it to its
original value.

Hence adding these signals together doesn't alter the
slew rate, as long as the total signal remains within the
defined full amplitude.


Agreed.

Does this logic hold for the sum of a full amplitude

20kHz and some other, lower frequency? Intuitively yes,
to me. A bit of simple trig would confirm.


The math supports your intuition.


What about smaller signals? Well, they will never have a
higher slew rate than the 20kHz at full amplitude, surely?


As long as they are band-limited to 20 KHz.

The agenda that seems to be hidden from Phil relates to the vast improvement
in the bandwidth of power transistors over the years. In the 60s and early,
large power devices used in power amps usually ran out of gas below 1 MHz.
Today for about the last 20 years, parts that beat that by a factor of 10 or
more are plentiful and inexpensive.


It is not hidden from me, and I have mentioned the same thing somewhere
in this thread, but since I was never claiming (as implied by PA) that
modern amps produce TIM, it is *almost* irrelevant. The "almost" part
comes from something I believe to be true, namely that the dynamic phase
shifting and other possible abuses of signals 80 dB below the main
signal in high feedback amps are *reduced* as the speed of the closed
loop increases, something that has indeed improved greatly not just
since the 60's, but since Otala wrote his papers in the 70's. However,
"improved" does not equal "perfect," or even "adequate," and since any
SS amp short of a Krell (if that) still is sonically challenged --
*especially* when it comes to the really low-level information --
compared to the best low or zero feedback triode amps, one has to
suspect that it is a problem that has only been reduced, not eliminated.
Given that there is room for improvement, it would be helpful if we
could figure out what is wrong.

Here you have not only my theory as to what is wrong (based mainly on
Otala's paper) -- problems caused by the higher feedback of SS amps,
among other SS problems -- but also a basic outline for a possible
solution. By all means, if you are aware of someone else who has pursued
my line of reasoning, and proved with actual experiments that it is
useless, post the information here (but don't waste our time with TIM
papers, since that is *not* what either I or Otala am/were talking
about). I will then publicly state, here, that you were RIGHT, and that
both my theory about one of the diseases of SS amps, and therefore my
proposed cures, were WRONG, and we can all move on in an attempt to
figure out the true reasons why all but the best SS amps suck when
compared to even very good tube amps, let alone the best ones.

Pragmatic Phil

I am still waiting for someone to define just what is the problem of dynamic phase
shift in amplifiers.

Is it a phase shift of high frequencies caused by AMPLITUDE changes of lower
frequencies
rather like the "doppler" effect in a speaker where the frequency of a 10kHz wave
will slightly change 50 times a second if there is a 50Hz tone also present?

I see no evidence of any doppler effects in an amplifier.

So just what is the problem we need to consider or fix????

Patrick Turner.

[Arny Krueger]

"Patrick Turner" wrote in message

..

So just what is the problem we need to consider or fix????

Finding a cork for Phil so as to stop the flow of weirdness.

[Sander deWaal]

"Phil Allison" said:


"Phil" toob-headman

" You know, I have terminal cancer, and maybe heart problems (waiting for
the results), "


** Don't be so modest with your medical boasting - you also have terminal
autism and bi-polar disorder.


" .... but I would rather be me, and dead soon, "


** Then we all have something to look forward to.



Now THIS is cute!

Impressed Phil



** To save everyone further grief - drop dead now.





........ Phil



A close DIY friend of mine recently died of cancer, I witnessed the
process closely.

I sincerely hope you won't ever have to face such a situation, or even
suffer from such a disease yourself, Phil. It's horrible.

--
"Due knot trussed yore spell chequer two fined awl miss steaks."

[Joseph Meditz]

Phil wrote:
Joseph Meditz wrote:

Phil Allison wrote:

"Andre Jute"


Let's hear some more about this dynamic phase shift that pours a pint
of vinegar into a Crown preamp.


** Dynamic phase shifting of audio signals is all around us, all the time.
The fact that cones move, continuously alters the origin and hence time of
arrival of any higher frequencies being simultaneously radiated. Phase
shift in degrees ( at any point in time) is simply 360 x cone excursion /
wavelength of the high frequency.

Some call this effect " Doppler Distortion" - a misnomer.



Hi Phil,

Here's my take on this interesting topic.

I say that this is precisely an acoustical frequency modulator. If you
input two sinusoids, one low and one high, then the spectrum of the
upper one will be spread out about its center. And the greater the
amplitude of the bass signal, the greater the modulation index. From
the modulation index one could predict what the side bands will look
like.

I found the term "Doppler Distortion" helpful. The situation here is
not exactly like the sound of the horn of a train passing a station.
Rather, it is the sound of the horn of a crazy train oscillating back
and forth across the station.

Joe

So, is an acoustical frequency modulator some type of equipment? It does
sound like what I *think* Otala is saying happens when a feedback amp
gets hold of two sinusoids, as you say. What is a good methos for seeing
this spread? Someone suggested (oh hell, I think it was Arny; a USEFUL
idea???) using a spectrum analyzer, maybe it's that simple?

By the way, I *think* PA is wrong, in a way. It may be that a cone
moving forward at a bass frequency can Doppler shift a high frequency
signal, but doesn't the mic that recorded the two frequncies to begin
with invert this process, thereby cancelling it out? Just thinking ...

Phil

Hi Phil,

I tried to respond to your email, but it bounced back twice.

Anyway, it looks as though your questions have been answered.
Regarding cancellation, I think that, even if you could use the very
same loudspeaker that generates the sound as a microphone to pick up
the sound, it would still not cancel the effect of the moving cone
because the sound reaching the "microphone" will be weaker than the
transmitted signal. Hence it would not move the "microphone" cone as
much, and its resulting rate of change of phase will be less than that
of the transmitting speaker.

Joe

[Phil]

Sander deWaal wrote:
"Phil Allison" said:


"Phil" toob-headman

" You know, I have terminal cancer, and maybe heart problems (waiting for
the results), "


** Don't be so modest with your medical boasting - you also have terminal
autism and bi-polar disorder.


" .... but I would rather be me, and dead soon, "


** Then we all have something to look forward to.




Now THIS is cute!

Impressed Phil



** To save everyone further grief - drop dead now.





........ Phil




A close DIY friend of mine recently died of cancer, I witnessed the
process closely.

I sincerely hope you won't ever have to face such a situation, or even
suffer from such a disease yourself, Phil. It's horrible.

Thank you for the hopeful wishes! I am trying to find ways to at least
delay that horrible ending, although f-NHL (follicular non-hidgkin's
lymphoma) has, I believe, an ending that is better, on average, than
some of the more ruthless cancers. The main drawback to the indolent
lymphomas in general is that they are 100% incurable, although f-NHL
folks have an average life expectency of 7 years (I've had mine 6-1/2),
so at least you usually get some time.

Phil

[Phil]

Patrick Turner wrote:

Phil wrote:


Arny Krueger wrote:


"Ian Iveson" wrote in
message k


Phil wrote:



Well, remember, the maximum slew rate found in audio
signals is much
greater than what a theoretical 20 KHz signal is going
to supply,

Yes and no, Phil.

Take 20kHz at full amplitude to define the required slew
rate.
Add another identical signal, in phase.

You now have twice the slew rate, as you think.

But the signal is also twice full amplitude, so it is not
comparable.
To make it comparable, you must reduce it to full
amplitude.
In so doing, you halve the slew rate, returning it to its
original value.

Hence adding these signals together doesn't alter the
slew rate, as long as the total signal remains within the
defined full amplitude.


Agreed.

Does this logic hold for the sum of a full amplitude


20kHz and some other, lower frequency? Intuitively yes,
to me. A bit of simple trig would confirm.


The math supports your intuition.



What about smaller signals? Well, they will never have a
higher slew rate than the 20kHz at full amplitude, surely?


As long as they are band-limited to 20 KHz.

The agenda that seems to be hidden from Phil relates to the vast improvement
in the bandwidth of power transistors over the years. In the 60s and early,
large power devices used in power amps usually ran out of gas below 1 MHz.
Today for about the last 20 years, parts that beat that by a factor of 10 or
more are plentiful and inexpensive.



It is not hidden from me, and I have mentioned the same thing somewhere
in this thread, but since I was never claiming (as implied by PA) that
modern amps produce TIM, it is *almost* irrelevant. The "almost" part
comes from something I believe to be true, namely that the dynamic phase
shifting and other possible abuses of signals 80 dB below the main
signal in high feedback amps are *reduced* as the speed of the closed
loop increases, something that has indeed improved greatly not just
since the 60's, but since Otala wrote his papers in the 70's. However,
"improved" does not equal "perfect," or even "adequate," and since any
SS amp short of a Krell (if that) still is sonically challenged --
*especially* when it comes to the really low-level information --
compared to the best low or zero feedback triode amps, one has to
suspect that it is a problem that has only been reduced, not eliminated.
Given that there is room for improvement, it would be helpful if we
could figure out what is wrong.

Here you have not only my theory as to what is wrong (based mainly on
Otala's paper) -- problems caused by the higher feedback of SS amps,
among other SS problems -- but also a basic outline for a possible
solution. By all means, if you are aware of someone else who has pursued
my line of reasoning, and proved with actual experiments that it is
useless, post the information here (but don't waste our time with TIM
papers, since that is *not* what either I or Otala am/were talking
about). I will then publicly state, here, that you were RIGHT, and that
both my theory about one of the diseases of SS amps, and therefore my
proposed cures, were WRONG, and we can all move on in an attempt to
figure out the true reasons why all but the best SS amps suck when
compared to even very good tube amps, let alone the best ones.

Pragmatic Phil


I am still waiting for someone to define just what is the problem of dynamic phase
shift in amplifiers.

Is it a phase shift of high frequencies caused by AMPLITUDE changes of lower
frequencies
rather like the "doppler" effect in a speaker where the frequency of a 10kHz wave
will slightly change 50 times a second if there is a 50Hz tone also present?

I see no evidence of any doppler effects in an amplifier.

So just what is the problem we need to consider or fix????

Patrick Turner.


Patrick, in some ways I am completely with you, and in some ways not. I
don't have, nor have I been able to find (so far), Otala's paper on the
conversion by feedback of amplitude distortion into phase distortion,
although I may be able to obtain Greiner's (sp?) paper. For obvious
reasons, it would be nice to have it/them. However, although many here
have pointed out that TIM is a non-issue, that is not what Otala was
talking about in this paper. Remember, his investigation into the
fundamental nature of feedback came after a BS session with several
other people in The Audio Critic (Stew Hegeman, Bruce Zadye, Mitch
Cotter, etc.), in which the basic nature of feedback was extensively
discussed. I have seen no references, other than the one by Greiner,
that *might* suggest there is even a limitation, let alone a flaw, in
Otala's mathematical proof regarding feedback. According to Aczel, he
incorporated ways of reducing feedback's negative effects in his design
for Harmon-Kardon's Citation XX, so if I/we could find a paper by Otala
on the Citation XX, even that might provide the answers!

On the other hand, I *think* you'll agree that high feedback amps very
often are sonically challenged, so a mechanism for problems does exist.
Therefore, even if we figure out exactly what feedback screws up, we
still have to figure out how to avoid those problems. This might be
easier if we could find the papers, but even the somewhat cryptic
description, "converts amplitude distortion into phase distortion" *may*
give us the information we need, assuming this description is correct.
To partially answer your question, therefore, the problem is probably
not one of amplitude, but amplitude *distortions*. Unfortunately, I
believe this refers to any "correction" of the signal by the feedback
loop, which would certainly appear to include the excess gain of the
open loop that is normally used to obtain the feedback, meaning that
high feedback amps constantly convert the excess gain of the open loop,
even if the amplifying devices are perfectly linear, into *some* type of
phase distortion.

The human ear no doubt has a threshold below which it cannot detect
phase distortion, so for a while you truly get "free lunch," an
improvement in amplitude distortions, with no detectable phase
distortions. This is probably also aided by using very fast devices. In
that BS session in TAC, they said the following:

[p 22, Cotter] "A loudspeaker contains a system that stores energy ...
we store energy in a loudspeaker and ... we release it backwards [into
the power amp]. [Otala] We measured about 50% of the energy coming back
during the next 50 milliseconds. [Cotter] Which is a hell of a long time
compared to the dimensions of most rooms -- or the dimensions of time
for most musically important events. The basic problem is, what happens
to that energy?"

They then addressed the issue of what happens to the energy from the
loudspeaker in the Bell Labs triode amps:

[p 23, Cotter] "But the thing that's interesting about these systems is
not only did they share this very low time dispersal, very low delay
property, but in effect, you had this terribly inefficient plate
resistance of the tube, which in the case of the 300B was a very linear
resistor ... what you had was an amplifier that could be envisioned
analytically as essentially a current source, shunted by a fairly fat
resistor, a fairly power-grabbing resistor, in parallel with whatever
the load was."

They also said (in various places) that a feedback amp must handle the
energy from the speaker by generating an error signal and putting it
back through the amp. It must correct the amplitude distortions
generated from the energy coming back from the speaker by using the
feedback loop, since there is no low impedance plate resistor, like you
find in a triode, to absorb this energy.

Otala then commented -- and this is before his paper on feedback --
about a feedback problem he had seen in an amp:

[p 23 Otala] I recently discovered a unit which did not produce TIM at
all, although it was described as producing lots of TIM-like distortion.
The effect was very simple. It was namely so, that since the poles of
the transfer function just moved up and down with current excitation, so
when used with a large amount of feedback, its phase margin was going up
and down. The frequency response varied, depending on the signal level.
Therefore it created very much this kind of time effects, phase
modulation or time modulation, whatever you wish. But here the important
thing is, once again, that effects like TIM, or this phase margin
shifting or whatever, are not related to the basic concept of feedback,
but a very poor application of the principles."

My impression is that after his more thorough, mathematical analysis
later, Otala found that actually, "this phase margin shifting," is
indeed related to the basic concept of feedback. And when you add both
the energy from the speaker and the (possibly) constant error of the
open loop, you have a lot of amplitude distortions that can be converted
into phase distortions in a feedback amp, assuming that phase shifting
IS a problem. And although the "what else can it be" form of reasoning
is not my favorite, since it is so unreliable, in this case, if feedback
"Doesn't either have problems Otala said it does!", as some here want to
believe, then what else is there that could possibly explain the fact
that high feedback amps DO SUCK?

It turns out that my initial thoughts on an alternative method of
feedback, one which only applies an error signal when there is actually
an error -- meaning that the high gain, which is moved to the feedback
loop, is no longer seen as an error -- is NOT equivalent to Black's
feedforward scheme, although it's very, very close. It is in fact
equivalent to the "Active-Error Feedback" described by J. R. MacDonald
in "Proc. IRE," vol 43, pp 808-813, July 1955, and for that matter
several other references that were printed both before and after
MacDonald's.

Phil

[Sander deWaal]

Phil said:

Sander deWaal wrote:

"Phil Allison" said:

"Phil" toob-headman wrote:

" You know, I have terminal cancer, and maybe heart problems (waiting for
the results), "


** Don't be so modest with your medical boasting - you also have terminal
autism and bi-polar disorder.


" .... but I would rather be me, and dead soon, "


** Then we all have something to look forward to.


Now THIS is cute!

Impressed Phil


** To save everyone further grief - drop dead now.

........ Phil


A close DIY friend of mine recently died of cancer, I witnessed the
process closely.

I sincerely hope you won't ever have to face such a situation, or even
suffer from such a disease yourself, Phil. It's horrible.


Thank you for the hopeful wishes! I am trying to find ways to at least
delay that horrible ending, although f-NHL (follicular non-hidgkin's
lymphoma) has, I believe, an ending that is better, on average, than
some of the more ruthless cancers. The main drawback to the indolent
lymphomas in general is that they are 100% incurable, although f-NHL
folks have an average life expectency of 7 years (I've had mine 6-1/2),
so at least you usually get some time.


Ummm........I was addressing Phil Allison, not you.
I'm sorry if it looked that way.
Phil A.'s quoting abilities leave somewhat to be desired, hence the
confusion.

FWIW, my friend died within 2 months of the dicovery.
In the process, they amputated his arm and part of his shoulder, since
the cancer was in there. A very aggressive form of cancer it was.
It already spread across his chest, and he chose not to be
radiation-treated, but to spend his last says with his family.
At 35 years, he left a mother and 2 kids behind.

--
"Due knot trussed yore spell chequer two fined awl miss steaks."

[Chris Hornbeck]

On Mon, 11 Sep 2006 21:50:29 GMT, Phil
wrote:

[p 23 Otala] I recently discovered a unit which did not produce TIM at
all, although it was described as producing lots of TIM-like distortion.
The effect was very simple. It was namely so, that since the poles of
the transfer function just moved up and down with current excitation, so
when used with a large amount of feedback, its phase margin was going up
and down. The frequency response varied, depending on the signal level.
Therefore it created very much this kind of time effects, phase
modulation or time modulation, whatever you wish. But here the important
thing is, once again, that effects like TIM, or this phase margin
shifting or whatever, are not related to the basic concept of feedback,
but a very poor application of the principles."

Ah, I'm beginning to see the source of the confusion. Otala
is describing an extremely non-linear amplifier, an abberation.
There are some monolythic op-amps made this way deliberately,
to optimize some other characteristics.

This shouldn't, however, be conflated with a conventional
linear amplifier. Whole different critter.


My impression is that after his more thorough, mathematical analysis
later, Otala found that actually, "this phase margin shifting," is
indeed related to the basic concept of feedback.

It's certainly not evident from the quotation above. And I'd
be really astonished if true; he's not a quack.

The rest of the stuff quoted is marginal to bogus.

All good fortune,

Chris Hornbeck
"You have to have an idea of what you are going to do,
but it should be a vague idea." - Pablo Picasso, 1946

[paul packer]

On Sun, 10 Sep 2006 13:13:05 GMT, Phil
wrote:


in case you're too stupid to get it

He's too stupid to get it.

[paul packer]

On Tue, 12 Sep 2006 00:01:28 +0200, Sander deWaal
wrote:


Thank you for the hopeful wishes! I am trying to find ways to at least
delay that horrible ending, although f-NHL (follicular non-hidgkin's
lymphoma) has, I believe, an ending that is better, on average, than
some of the more ruthless cancers. The main drawback to the indolent
lymphomas in general is that they are 100% incurable, although f-NHL
folks have an average life expectency of 7 years (I've had mine 6-1/2),
so at least you usually get some time.


Ummm........I was addressing Phil Allison, not you.
I'm sorry if it looked that way.

That's a relief, Sander. I thought you'd suddenly lost all
sensitivity!

[Phil]

paul packer wrote:
On Sun, 10 Sep 2006 13:13:05 GMT, Phil
wrote:



in case you're too stupid to get it


He's too stupid to get it.

So it would appear! That's all right, I'm sure he thinks he's much
smarter and more clever than you and me put together. He's a winner! The
fact that he forget to check which race he is winning, versus the race
he should be winning, will never seriously occur to him.

Phil

[Phil]

Chris Hornbeck wrote:

On Mon, 11 Sep 2006 21:50:29 GMT, Phil
wrote:


[p 23 Otala] I recently discovered a unit which did not produce TIM at
all, although it was described as producing lots of TIM-like distortion.
The effect was very simple. It was namely so, that since the poles of
the transfer function just moved up and down with current excitation, so
when used with a large amount of feedback, its phase margin was going up
and down. The frequency response varied, depending on the signal level.
Therefore it created very much this kind of time effects, phase
modulation or time modulation, whatever you wish. But here the important
thing is, once again, that effects like TIM, or this phase margin
shifting or whatever, are not related to the basic concept of feedback,
but a very poor application of the principles."


Ah, I'm beginning to see the source of the confusion. Otala
is describing an extremely non-linear amplifier, an abberation.
There are some monolythic op-amps made this way deliberately,
to optimize some other characteristics.

This shouldn't, however, be conflated with a conventional
linear amplifier. Whole different critter.



My impression is that after his more thorough, mathematical analysis
later, Otala found that actually, "this phase margin shifting," is
indeed related to the basic concept of feedback.


It's certainly not evident from the quotation above. And I'd
be really astonished if true; he's not a quack.

The rest of the stuff quoted is marginal to bogus.

All good fortune,

Chris Hornbeck
"You have to have an idea of what you are going to do,
but it should be a vague idea." - Pablo Picasso, 1946

Could be ... of course, then we really are back to square one as to what
the heck does cause high feedback amps, meaning the linear amps, to
sound so bad. Maybe it's actually the fact that along with the high
feedback that came with solid state, we used "devices with silicon
capacitances," instead of "devices with vacuum capacitances," to obtain
the error signal, thereby polluting the signal with garbage from the
silicon capacitors. My *guess*, however, is that feedback itself is
causing a problem, and I still hope to see the papers for and against
the idea of feedback converting amplitude into phase distortion before I
give up on the idea.

Phil

[Phil]

Sander deWaal wrote:

Phil said:


Sander deWaal wrote:


"Phil Allison" said:



"Phil" toob-headman wrote:


" You know, I have terminal cancer, and maybe heart problems (waiting for
the results), "



** Don't be so modest with your medical boasting - you also have terminal
autism and bi-polar disorder.



" .... but I would rather be me, and dead soon, "



** Then we all have something to look forward to.



Now THIS is cute!


Impressed Phil



** To save everyone further grief - drop dead now.


........ Phil




A close DIY friend of mine recently died of cancer, I witnessed the
process closely.



I sincerely hope you won't ever have to face such a situation, or even
suffer from such a disease yourself, Phil. It's horrible.




Thank you for the hopeful wishes! I am trying to find ways to at least
delay that horrible ending, although f-NHL (follicular non-hidgkin's
lymphoma) has, I believe, an ending that is better, on average, than
some of the more ruthless cancers. The main drawback to the indolent
lymphomas in general is that they are 100% incurable, although f-NHL
folks have an average life expectency of 7 years (I've had mine 6-1/2),
so at least you usually get some time.



Ummm........I was addressing Phil Allison, not you.
I'm sorry if it looked that way.
Phil A.'s quoting abilities leave somewhat to be desired, hence the
confusion.

FWIW, my friend died within 2 months of the dicovery.
In the process, they amputated his arm and part of his shoulder, since
the cancer was in there. A very aggressive form of cancer it was.
It already spread across his chest, and he chose not to be
radiation-treated, but to spend his last says with his family.
At 35 years, he left a mother and 2 kids behind.

Oops! He so needs to change his name ...

The Real Phil

[Chris Hornbeck]

On Tue, 12 Sep 2006 00:57:40 GMT, Phil
wrote:

Could be ... of course, then we really are back to square one as to what
the heck does cause high feedback amps, meaning the linear amps, to
sound so bad.

Well, this part is really a stretch for most, including me.
"So bad"? What does this even mean?

Maybe it's actually the fact that along with the high
feedback that came with solid state, we used "devices with silicon
capacitances," instead of "devices with vacuum capacitances," to obtain
the error signal, thereby polluting the signal with garbage from the
silicon capacitors.

The "error signal" in linear feedback is just a notion; no
such thing exists. Output signal is fed back to an input
terminal and compared *within the amplifier* to input signal.

There is no error signal in ordinary linear feedback. This
holds true independent of device construction and method
of employment. There's only input and output.


My *guess*, however, is that feedback itself is
causing a problem, and I still hope to see the papers for and against
the idea of feedback converting amplitude into phase distortion before I
give up on the idea.

I'll get Otala's original paper out to ya tomorrow morning,
and it might provide a little historical framework. Please
beware of stuff like _The Audio Critic_; it's whack.

All good fortune,

Chris Hornbeck
"You have to have an idea of what you are going to do,
but it should be a vague idea." - Pablo Picasso, 1946

[paul packer]

On Tue, 12 Sep 2006 00:50:13 GMT, Phil
wrote:

paul packer wrote:
On Sun, 10 Sep 2006 13:13:05 GMT, Phil
wrote:



in case you're too stupid to get it


He's too stupid to get it.

So it would appear! That's all right, I'm sure he thinks he's much
smarter and more clever than you and me put together. He's a winner! The
fact that he forget to check which race he is winning, versus the race
he should be winning, will never seriously occur to him.

Phil


It might now. Then again....

[Patrick Turner]

Chris Hornbeck wrote:

On Tue, 12 Sep 2006 00:57:40 GMT, Phil
wrote:

Could be ... of course, then we really are back to square one as to what
the heck does cause high feedback amps, meaning the linear amps, to
sound so bad.

Well, this part is really a stretch for most, including me.
"So bad"? What does this even mean?

Maybe it's actually the fact that along with the high
feedback that came with solid state, we used "devices with silicon
capacitances," instead of "devices with vacuum capacitances," to obtain
the error signal, thereby polluting the signal with garbage from the
silicon capacitors.

The "error signal" in linear feedback is just a notion; no
such thing exists. Output signal is fed back to an input
terminal and compared *within the amplifier* to input signal.

The input signal is compared to a fraction of the output signal
by means of a single tube acting as a differential amp or a pair of
differential tubes in an LTP.

Only the difference between the signal fed back is amplified by the amp.
This difference signal will contain the non-linearities, ie
artifacts not present in the input signal and be amplified to oppose their
own production,
so the error signal which is defined as the signal within the amp after the
summing/comparing process
does contain non linearities.



There is no error signal in ordinary linear feedback. This
holds true independent of device construction and method
of employment. There's only input and output.

But what is ordinary linear feedback? no feedback path is perfectly always
linear.

There are always TWO inputs and ONE output in the simplest NFB amplifier,
unless its a balanced input and output
and then there may be more input/output ports.



My *guess*, however, is that feedback itself is
causing a problem, and I still hope to see the papers for and against
the idea of feedback converting amplitude into phase distortion before I
give up on the idea.

I'll get Otala's original paper out to ya tomorrow morning,
and it might provide a little historical framework. Please
beware of stuff like _The Audio Critic_; it's whack.

All good fortune,

Chris Hornbeck
"You have to have an idea of what you are going to do,
but it should be a vague idea." - Pablo Picasso, 1946

I'm ignoring most pots on dynamic phase shift because nobody
has bothered to define what the **** it actually is.

So like a flock of chooks you can all cluck onwards to
cluckdom which is largely free of any wisdom about dynamic phase shift IMHO.

Patrick Turner.

[Andre Jute]

Patrick Turner wrote:
I'm ignoring most posts on dynamic phase shift because nobody
has bothered to define what the **** it actually is.

Don't be ridiculous, Patrick. You can't define something which never
existed and, if it did, is confined to temporary importance (and
excused by) the fact that transistors back a generation ago were even
more dire than they are now. In these emotive surroundings, with the
silicon brigade taking the slightest slur on their fave as an attack on
their mother's honour, it is perhaps not surprising that it took 105
messages to decide ... what I knew when I mailed the first post in the
thread, and signalled loud and clear by "amazing".

So like a flock of chooks you can all cluck onwards to
cluckdom which is largely free of any wisdom about dynamic phase shift IMHO.

Hey, the silicon slime has rights too. In particular, they insist on
their right to beat up on an earnest innocent. See, it "proves" they
are "engineers".

Patrick Turner.

"Incredible" hardly describes this thread. And it leaves us with no
answers about why excessive NFB sounds like ****.

Andre Jute
"You can wait 'til more important things get taken care of."
-- Ned Carlson of TubeZone to a Customer who already waited *14 weeks*
for his tubes.

[Arny Krueger]

"Phil" wrote in message


On the other hand, I *think* you'll agree that high
feedback amps very often are sonically challenged, so a
mechanism for problems does exist.

Addressing a tube advocate, this is both a sure thing and pretty much
meaningless. It's like asking a member of the New York Yankees baseball team
whether or not they like baseball.

Therefore, even if we
figure out exactly what feedback screws up, we still have
to figure out how to avoid those problems.

Figuring out what feedback screws up (in well-designed systems) is very
difficult. No matter what all the trolls and tubies say, NASA is still going
to use feedback control systems to send man into space. Nuclear power plants
are still going use loop feedback no matter what Phil or Pat agree on. No
matter how many OCD-ridden audiophiles buy into this weirdness, just about
every piece of audio gear in the world, including virtually all of the
production gear, is going to based on the effectiveness of loop feedback.

And here is the irony, just about every recording that Phil and Pat have
ever played on an audio system was produced using high-feedback amplfiers.
Phil and Pat can agree on what they like, but just about every extant piece
of vinyl they've ever played was made using a cutter head with loop
feedback, and/or driven by power amps with loop feedback.

This might be
easier if we could find the papers, but even the somewhat
cryptic description, "converts amplitude distortion into
phase distortion" *may* give us the information we need,
assuming this description is correct.

Contrary to popular belief among our local paranoids, phase distortion can
be readily measured if you have the right equipment. The margins for
audibility or inaudibility of phase distortrion are known to people who
study psychoacoustics. The world is full of audio gear that simply has no
audible phase distortion, their heavy use of loop feedback notwithstanding.

To partially answer
your question, therefore, the problem is probably not one
of amplitude, but amplitude *distortions*.

Yet another one of those things that is readily measured, and which the ear
has well-known tolerance.

Unfortunately,
I believe this refers to any "correction" of the signal
by the feedback loop, which would certainly appear to
include the excess gain of the open loop that is normally
used to obtain the feedback, meaning that high feedback
amps constantly convert the excess gain of the open loop,
even if the amplifying devices are perfectly linear, into
*some* type of phase distortion.

High feedback amps do not necessarily do any such thing. This one of those
things that needs a sighted listening test to "find". Hence all of Phil's
phobias and false claims about bias-controlled listening tests.

The human ear no doubt has a threshold below which it
cannot detect phase distortion, so for a while you truly
get "free lunch," an improvement in amplitude
distortions, with no detectable phase distortions.

And these thresholds are far higher than the levels of any such distortions
in a wide range of conventially-designed audio gear. BTW much of this audio
gear is present in the signal chain used to produce the recordings that Phil
uses when he psych's himself up to *hear* them. Odd that he can't hear them,
eh?

[Arny Krueger]

"Phil" wrote in message


Could be ... of course, then we really are back to square
one as to what the heck does cause high feedback amps,
meaning the linear amps, to sound so bad.

Listener bias. That's why DBT's don't confirm the existence of this
so-called problem.

[Phil Allison]

"Arny Krueger"

And here is the irony, just about every recording that Phil and Pat have
ever played on an audio system was produced using high-feedback amplfiers.
Phil and Pat can agree on what they like, but just about every extant
piece of vinyl they've ever played was made using a cutter head with loop
feedback, and/or driven by power amps with loop feedback.


** The famous Crown DC300A model was popular as a stereo LP cutter head amp.

It's got a primitive uA739 dual op-amp at the input.

It's got oodles of loop NFB.

Mediocre slew rate, by some estimates.

Contemporary alternatives were all inferior.


LOL !


......... Phil

[Arny Krueger]

"Phil Allison" wrote in message

"Arny Krueger"

And here is the irony, just about every recording that
Phil and Pat have ever played on an audio system was
produced using high-feedback amplfiers. Phil and Pat can
agree on what they like, but just about every extant
piece of vinyl they've ever played was made using a
cutter head with loop feedback, and/or driven by power
amps with loop feedback.


** The famous Crown DC300A model was popular as a stereo
LP cutter head amp.
It's got a primitive uA739 dual op-amp at the input.

It's got oodles of loop NFB.

Mediocre slew rate, by some estimates.

Contemporary alternatives were all inferior.

LOL !

The predecessor tubed amps were often MacIntosh 300-watters that had plenty
of local and loop feedback, as well. It's been a long time since I've seen
the schematic for a MC300, but I believe that it followed the pattern of the
275.

http://www.drtube.com

[Phil Allison]

"Arny Krueger"
"Phil Allison"

And here is the irony, just about every recording that
Phil and Pat have ever played on an audio system was
produced using high-feedback amplfiers. Phil and Pat can
agree on what they like, but just about every extant
piece of vinyl they've ever played was made using a
cutter head with loop feedback, and/or driven by power
amps with loop feedback.


** The famous Crown DC300A model was popular as a stereo
LP cutter head amp.
It's got a primitive uA739 dual op-amp at the input.

It's got oodles of loop NFB.

Mediocre slew rate, by some estimates.

Contemporary alternatives were all inferior.

LOL !

The predecessor tubed amps were often MacIntosh 300-watters that had
plenty of local and loop feedback, as well. It's been a long time since
I've seen the schematic for a MC300, but I believe that it followed the
pattern of the 275.

http://www.drtube.com



** Tube amps are just so compromised by that damn great lump of iron hanging
off the output.

You would not believe the massive phase shift these boat anchors exhibit at
both ends of the audio band.

Totally prevents using a **decent amount** of loop feedback or the whole
amp becomes HORRIBLY unstable.





........ Phil

[Patrick Turner]

Andre Jute wrote:

Patrick Turner wrote:
I'm ignoring most posts on dynamic phase shift because nobody
has bothered to define what the **** it actually is.

Don't be ridiculous, Patrick. You can't define something which never
existed and, if it did, is confined to temporary importance (and
excused by) the fact that transistors back a generation ago were even
more dire than they are now. In these emotive surroundings, with the
silicon brigade taking the slightest slur on their fave as an attack on
their mother's honour, it is perhaps not surprising that it took 105
messages to decide ... what I knew when I mailed the first post in the
thread, and signalled loud and clear by "amazing".

So like a flock of chooks you can all cluck onwards to
cluckdom which is largely free of any wisdom about dynamic phase shift IMHO.

Hey, the silicon slime has rights too. In particular, they insist on
their right to beat up on an earnest innocent. See, it "proves" they
are "engineers".

Patrick Turner.

"Incredible" hardly describes this thread. And it leaves us with no
answers about why excessive NFB sounds like ****.

Andre Jute
"You can wait 'til more important things get taken care of."
-- Ned Carlson of TubeZone to a Customer who already waited *14 weeks*
for his tubes.

Some things go better with NFB.
This week I had the irksome job for a day and a half to re-engineer a 1965
Phillips "Music Theatre"
concoction of gram with ceramic cart and truly awful SS AM radio.

Half but not all the transistors were germanium. Some had become so noisy
that all the applied NFB couldn't cure it at all.
I replaced all the germanium except the outputs which have survived OK and of
course the bipolar silicon types
in the two stage preamp and driver stage of the power amps had more gain so hence
more applied NFB.
I re-did the attrocious circuitry by Phillips; and if anyone deserves to be hung,
drawn and
quartered for giving solid state a terrible reputation, it has to be the ****ed up
thinking
of the guys who worked in companies like Phillips ( and many of the other
companies ) at that time.
The idea of a flat response, absense of do-das and simplicity is totally absent
and their efforts
sounded far worse than the tube gear that the SS had begun to replace.

Even the AM radio tuner which is a module the size of a matchbox with 3 IF single
tuned coils
at 3 slightly different frequencies is a ******* of the thing to tune well by ear
and gives no better
AF bandwidth than the critically double tuned IFTs in a tube set, with switchable
selectrivity
for wide bw for locals, and low distortion due to wide dynamic range of the tubes.

Solid state really was NO Improvement where it should have been in a radio
had the designers used the right sort of double tuned IFTs but these were deemed
too
expensive to make and deploy.
It's possible to make an exceptional radio with all SS but the human temptation to
dumb everything down
by arsoles in Phillips was triumph of gross mediocrity.

The power amps are complementary pair germanium AD161 and AD162 coupled via 1,000
uF to the speakers.
One rail of +27V is used and one driver NPN transistor and one PNP silicon input
transistor is used.
About 8 watts or as much as a 300B is available to the listener.
Such a simple amp. And after replacing the ge driver transistor with a BD139, the
gain went up hugely
and distortion went low and bandwidth was from 30Hz to 800kHz, ( yes, 800kHz ).
I tamed the bw with passive cap at the input rather than have a massive amount of
C across the
FB resistor from the output to Q1 emitter.
I altered a few other C values to get the LF pole down from the initial 70Hz and
to stop
leak through from the preamp to power amp driver via the common rail filtering.

I lost count of the faults in the engineering.
The high impedance volume control with built in variable loudness networks had a
terrible effect on the sound.
The tone controls were anything but flat when in the flat position.
Bass and treble rolled off before they should but were peaked badly.

All the choices of compensation all over the circuits and evidence of silly
*******s applying
stupid silly pet theories about audio abounded, and THIS was what went a long way
to give SS
a rotten name, rather than the actual use of silicon or even the worse germanium
itself.

But once rewiring was completed the preamp amd power amps were sounding acceptable

as long as the source wasn't the radio within the set or the TT and ceramic cart.
In this case the cart and the radio determine the crumminess of the sound with the
typical
brashy hashy sandpapery top end so typical of budget SS **** of the 1960s and 70s;

basically it is lots of IMD in the sources.

1/2 the cart does not work and I have to replace the cart from a place in Holland
if the client chooses that path but I reckon any budget modern TT with built in
magnetic
phono amp using FB around an op-amp will sound better than the original ceramic
cart
and high impedance feed to the preamp, and the gord-knows-what downforce of such a
cart
on the records.

If I can talk the client into chucking out the Phillips 1965 idea of what a TT
should have been
then the whole set will begin to actually sound reasonable rather than remain
faulty but nevertheless
a heck of a lot better than what it was when it came home from the shop in 1965.
For 40 years this **** of a **** box has been filling someone's lounge with music
that
was ghastly and yet these ppl happily put up with it and wanted a repair rather
than want to
retire the crap to a dumpster bin where a very large proportion of early SS gear
belongs.
And not necessarily because of the silicon itself, but because of the severe
limitations of the
mental capacities of the company design department. What a bunch of nerds they
truly were!!!!!

I drive a 1986 Ford Laser with the original AM/FM radio supplied by Ford when
motor car companies began
to fit radios to cars they sold as a standard item.
The car radio provided by Ford I have is another ode to the crappiness of SS
****ological inventiveness of
would be nerds who must have been the next generation of such like after the first
lot who gained employment
under false pretences at Phillips and other companies 20 years before.......

Meanwhile I see you think that dynamic phase shift of part or all of the signal
content
by amplitude changes to part or all of the signal does not exist because of some
reason why it
should not be able to exist. Fair enough, and if something like doppler
distortions did occur
in a power or preamp you'd think someone would have spotted it by now, and written
reams about it
in concise easy to undertsand terms.

Meanwhile, my expereince at building NEW SS power amps using quite large amounts
of NFB
has never proved to me that high NFB are ALWAYS bad sounding, and I have on
occasions
demonstrated to gathered ppl on musical evenings that a high NFB SS amp could
sound
identical, or at least just as well as a tube amp with mild NFB.
However some of the budget Creeks and Cambridge amps were quite awful as well as a
range of
other amps and receivers I have repaired over the years, and often I have worked
on a few
SS amps and had them running as perfectly as i could in the technical sense and
thought not bad until
I switched to something with bottles again and then heard my brain's sigh of
relief....

So my own humble explanation about SS gear I have made which doesn't sound to bad
despite all
the bagfuls of NFB is that I made it with some regard to power supply quality
and rail regulation of input stages rather than rely on NFB to reduce the noise as
well
as the THD and IMD and Rout.
The SS power amps I have made could all actually be tested without the global NFB
connected,
so that full power of 30Vrms into the load could be examined with only 2 mV of
input,
and without the output signal being a mass of noise and poor bandwidth like many
SS amps with their global NFB disconnected.

The schematics of several SS amps all with varying amounts of NFB are
explained at my website.

I will say that class A SS amps simply don't need much NFB, and need no more than
a
pentode amp which must have at least 20dB to reduce its Rout to acceptable
and usable levels. Everyone should know that triode amps don't necessarily need
any NFB because
of the local NFB within the triode and the resulting low Ra compared to any load
driven.

So if anyone wanted to make a simple PP class A SS amp they could do worse than
have a complementary pair of emitter followers with darlington bjts or source
follower mosfets and a linear
drive amp using the usual class A ziclai pnp/npn array of two transistors set up
to have excessive dynamic range compared to what is actually used.

I'll still prefer tubes.

Patrick Turner.

[Ruud Broens]

"Phil Allison" wrote in message
...
:
:
: ** Tube amps are just so compromised by that damn great lump of iron hanging
: off the output.
:
: You would not believe the massive phase shift these boat anchors exhibit at
: both ends of the audio band.
:
: Totally prevents using a **decent amount** of loop feedback or the whole
: amp becomes HORRIBLY unstable.
:
: ....... Phil
:
i'd call that a massive generalisation.
exibit A sowter U 061,
leakage inductance 86 dB below inductance,
- 0.5 dB 10Hz 42 kHz
controlled hf roll off from 100 kHz
0.05 % THD at 100W, 1kHz, 0.5 % at 22Hz 100W

can you give us the ^massive^ numbers ?

Rudy

[Patrick Turner]

Phil Allison wrote:

"Arny Krueger"
"Phil Allison"

And here is the irony, just about every recording that
Phil and Pat have ever played on an audio system was
produced using high-feedback amplfiers. Phil and Pat can
agree on what they like, but just about every extant
piece of vinyl they've ever played was made using a
cutter head with loop feedback, and/or driven by power
amps with loop feedback.


** The famous Crown DC300A model was popular as a stereo
LP cutter head amp.
It's got a primitive uA739 dual op-amp at the input.

It's got oodles of loop NFB.

Mediocre slew rate, by some estimates.

Contemporary alternatives were all inferior.

LOL !

The predecessor tubed amps were often MacIntosh 300-watters that had
plenty of local and loop feedback, as well. It's been a long time since
I've seen the schematic for a MC300, but I believe that it followed the
pattern of the 275.

http://www.drtube.com


** Tube amps are just so compromised by that damn great lump of iron hanging
off the output.

You would not believe the massive phase shift these boat anchors exhibit at
both ends of the audio band.

Totally prevents using a **decent amount** of loop feedback or the whole
amp becomes HORRIBLY unstable.

....... Phil

Phil, I do beg to differ.

The OPT when it is well made can be a superb coupling device over a bandwidth
which extends from 15Hz to 300kHz at full power and
from 3Hz to 300kHz at low power used for average listening.
I have wound plenty of wide BW OPTs.
Because the amps work with so much class A more than a total of 16dB of local
and global NFB is not needed.

Quad II is an example of adequate NFB and they are stable even though the OPT
is a toy compared to what might have been made if Mr Walker and the guys
surrounding him had seen fit to
produce all those years ago.

The problem isn't with the iron, its with the guys who design the gear,
and the limitations imposed by bean counters.

McIntosh have a fair amount of local NFB in their output stages and then apply
much additional NFB globally; EAR509 is another amp which does a similar thing
to make a class B amp perform well technically.
The McI amps were renowned for their low thd and Rout and stablity.
Whether or not they sound terrible is something I leave the audiophiles to argue
about,
but after listening to music through a McI powered system I cannot agree they
sound awful.

For the doubters about McI and high NFB, they can be arranged to run in class A
and with less NFB and internal gain, and who is to say they'd be worse sounding
then?
And with such a mod they'd even be more stable than they are already...

Patrick Turner.

[Arny Krueger]

"Ruud Broens" wrote in message

"Phil Allison" wrote in message
...


** Tube amps are just so compromised by that damn great
lump of iron hanging off the output.

You would not believe the massive phase shift these boat
anchors exhibit at both ends of the audio band.

Totally prevents using a **decent amount** of loop
feedback or the whole amp becomes HORRIBLY unstable.

....... Phil

i'd call that a massive generalisation.
exibit A sowter U 061,
leakage inductance 86 dB below inductance,
- 0.5 dB 10Hz 42 kHz
controlled hf roll off from 100 kHz
0.05 % THD at 100W, 1kHz, 0.5 % at 22Hz 100W

can you give us the ^massive^ numbers ?

You gave us a good one:

"0.5 % at 22Hz 100W"

....and that's just the output transformer. It doesn't include the thermionic
noise and distortion generator(s) that go with it.

[Ruud Broens]

"Arny Krueger" wrote in message
. ..
: "Ruud Broens" wrote in message
:
: "Phil Allison" wrote in message
: ...
:
:
: ** Tube amps are just so compromised by that damn great
: lump of iron hanging off the output.
:
: You would not believe the massive phase shift these boat
: anchors exhibit at both ends of the audio band.
:
: Totally prevents using a **decent amount** of loop
: feedback or the whole amp becomes HORRIBLY unstable.
:
: ....... Phil
:
: i'd call that a massive generalisation.
: exibit A sowter U 061,
: leakage inductance 86 dB below inductance,
: - 0.5 dB 10Hz 42 kHz
: controlled hf roll off from 100 kHz
: 0.05 % THD at 100W, 1kHz, 0.5 % at 22Hz 100W
:
: can you give us the ^massive^ numbers ?
:
: You gave us a good one:
:
: "0.5 % at 22Hz 100W"
:
: ...and that's just the output transformer. It doesn't include the thermionic
: noise and distortion generator(s) that go with it.
:
Ahh, Arny likes numbers, eh ?
OK, bet you a 1000000 dollars, your speakers won't even come
near 0.5 % with a 100 W input at 22 Hz.... 10 % would be a more like it
~just your speakers we're talking about~

so, if you're obsessed with being right,
why not get much, much better speakers

hehe
R.
(or use mfb)

[Arny Krueger]

"Ruud Broens" wrote in message

"Arny Krueger" wrote in message
. ..
"Ruud Broens" wrote in message

"Phil Allison" wrote in message
...


** Tube amps are just so compromised by that damn great
lump of iron hanging off the output.

You would not believe the massive phase shift these
boat anchors exhibit at both ends of the audio band.

Totally prevents using a **decent amount** of loop
feedback or the whole amp becomes HORRIBLY unstable.

....... Phil

i'd call that a massive generalisation.
exibit A sowter U 061,
leakage inductance 86 dB below inductance,
- 0.5 dB 10Hz 42 kHz
controlled hf roll off from 100 kHz
0.05 % THD at 100W, 1kHz, 0.5 % at 22Hz 100W

can you give us the ^massive^ numbers ?

You gave us a good one:

"0.5 % at 22Hz 100W"

...and that's just the output transformer. It doesn't
include the thermionic noise and distortion generator(s)
that go with it.

Ahh, Arny likes numbers, eh ?

Hmm, another guy who likes to externalize rather than take responsbility
for issues that he has raised.

Ruud, you're the guy who brought these numbers up, now stand behind them or
quit.

OK, bet you a 1000000 dollars, your speakers won't even
come
near 0.5 % with a 100 W input at 22 Hz.... 10 % would be
a more like it ~just your speakers we're talking
about~

Hmm, tubed equipment - what you buy to match the quality of the other worst
part of your audio system.

so, if you're obsessed with being right,
why not get much, much better speakers

As if speakers were all that there is to listen to.

As if we buy stereo equipment to match the weakest link in our systems.

[Ruud Broens]

"Arny Krueger" wrote in message
. ..
: "Ruud Broens" wrote in message
:

: ** Tube amps are just so compromised by that damn great
: lump of iron hanging off the output.
:
: You would not believe the massive phase shift these
: boat anchors exhibit at both ends of the audio band.
:
: Totally prevents using a **decent amount** of loop
: feedback or the whole amp becomes HORRIBLY unstable.
:
: ....... Phil
:
: i'd call that a massive generalisation.
: exibit A sowter U 061,
: leakage inductance 86 dB below inductance,
: - 0.5 dB 10Hz 42 kHz
: controlled hf roll off from 100 kHz
: 0.05 % THD at 100W, 1kHz, 0.5 % at 22Hz 100W
:
: can you give us the ^massive^ numbers ?
:
: You gave us a good one:
:
: "0.5 % at 22Hz 100W"
:
: ...and that's just the output transformer. It doesn't
: include the thermionic noise and distortion generator(s)
: that go with it.
:
: Ahh, Arny likes numbers, eh ?
:
: Hmm, another guy who likes to externalize rather than take responsbility
: for issues that he has raised.
:
: Ruud, you're the guy who brought these numbers up, now stand behind them or
: quit.

uhmm, right, the issue i raised being, no such thing as *massive* faults
necessarily connected with OT's - raised & not been refuted as far as i can c

:
: OK, bet you a 1000000 dollars, your speakers won't even
: come near 0.5 % with a 100 W input at 22 Hz....
: 10 % would be a more like it
: ~just your speakers we're talking about~
:
: Hmm, tubed equipment - what you buy to match the quality of the other worst
: part of your audio system.

hmm, dodging the issue would be an understatement here, eh ?

:
: so, if you're obsessed with being right,
: why not get much, much better speakers
:
: As if speakers were all that there is to listen to.
:

true but you gotta start somewhere
(or work on your personality

: As if we buy stereo equipment to match the weakest link in our systems.
:
: ?no secret door

[Phil Allison]

"Patrick Turner"

** Tube amps are just so compromised by that damn great lump of iron
hanging
off the output.

You would not believe the massive phase shift these boat anchors exhibit
at
both ends of the audio band.

Totally prevents using a **decent amount** of loop feedback or the whole
amp becomes HORRIBLY unstable.


Phil, I do beg to differ.


** Like the true ****head you are.


Because the amps work with so much class A more than a total of 16dB of
local
and global NFB is not needed.


** 16 dB of loop NFB is all that can be applied.

At mid band frequencies.

Backs up what I said completely.




........ Phil

[Phil Allison]

"Ruud Broens"
:
: ** Tube amps are just so compromised by that damn great lump of iron
hanging
: off the output.
:
: You would not believe the massive phase shift these boat anchors exhibit
at
: both ends of the audio band.
:
: Totally prevents using a **decent amount** of loop feedback or the
whole
: amp becomes HORRIBLY unstable.
:
:
i'd call that a massive generalisation.


** I'd call YOU a massive ****WIT !!!



exibit A sowter U 061,
leakage inductance 86 dB below inductance,
- 0.5 dB 10Hz 42 kHz
controlled hf roll off from 100 kHz
0.05 % THD at 100W, 1kHz, 0.5 % at 22Hz 100W

can you give us the ^massive^ numbers ?



** Where are the * phase shift * numbers - ****wit ??

Lets see them for various load conditions too.

Even the best tube amp designs have only 20 dB of loop NFB.




........ Phil