Dynamic phase shift

[Andre Jute]

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

[Phil Allison]

"Andre Jute"

( snip drivel from unfortunate namesake)


> 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.

Dynamic phase shift in hi-fi amps and pre-amps is a myth - closely related
to the old slew rate myth.

Remember TIM and SID ???

Long dead now, poor fellows.



> 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 ****.


** Quad founder, Peter Walker, was widely quoted saying in relation to
amplifiers:

" If you don't like what you hear coming out, pay more attention to what is
going in."

In reality, it was a polite dig at the many and ongoing misdeeds of
recording industry, which he held in deep contempt.

The regular, live FM broadcasts of classical music by the BBC from venues in
in London was his idea of reference signal quality.




....... Phil

[Patrick Turner]

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 ****.

First he needs to define what is occuring. I think he means phase modulation
by the dynamics of the amplitude changes, so that during
increase and decrease of signal amplitudes, the phase of a signal
is tweaked to lag or lead during the amplitude change.

Let's see what he really means to say.

Patrick Turner.

>
>
> 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

[Phil]

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
>
Pretty much what Patrick said, although I need to reply in the original
thread. What Matti Otala PROVED -- and Dr. Ottala was up there with
Richard Heyser, not just a professor, but the Director of the Technical
Research Center of Finland, and the guy who published many of the
original papers on TIM (transient Intermodulation Distortion), so what
he said should at least *intially* be taken seriously -- was that the
amplitude distortions of the open loop are transformed into phase
distortions of the closed loop, where the low frequency signals phase
modulate the high frequency signals. I *think* this means that the high
frequency signals move back and forward in time in the presense of low
frequency signals, something that is actually quite difficult to
measure, although all too easy to hear. It has some rather interesting
implications about feedback, and the optimum configurations(?) of
feedback (what's the word that refers to the various types of feedback
electrical circuits?), which I wil hopefully get to sometime soon. In
"The Audio Critic," Vol 2, #2, 1979, p 37, Peter Aczel said Otala's
technical paper was to be delivered on Feb. 25, 1980, at the 65th
convention of teh AES in London. I assume that the paper was published
soon afterward in the JAES, but I'm not certain. Guess I should go by
the UT library and have a look! (Hey, what's the use of living in the
"liberal armpit" of Texas -- Austin -- if you don't make use of its
assets? ;-)

Phil

[Phil Allison]

"Phil"
Andre Jute 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 ****.
>>
> Pretty much what Patrick said, although I need to reply in the original
> thread. What Matti Otala PROVED --


** Otala never proved one, single commercial hi-fi amp suffered from TIM in
a way that was audible.

Many others have proved conclusively that TIM ( ad his cousin SID) is a
furphy.


>and Dr. Ottala was up there with Richard Heyser, not just a professor, but
>the Director of the Technical Research Center of Finland, and the guy who
>published many of the original papers on TIM (transient Intermodulation
>Distortion), so what he said should at least *intially* be taken seriously


** It was - then got utterly debunked by others in the field wordwide.

The debunking unfortunately did get the NOT the same publicity as Otala's
hypothesis.

So, ignorant ****WITS like you never heard about it.



-- was that the
> amplitude distortions of the open loop are transformed into phase
> distortions of the closed loop, where the low frequency signals phase
> modulate the high frequency signals. I *think* this means that the high
> frequency signals move back and forward in time in the presense of low
> frequency signals, something that is actually quite difficult to measure,
> although all too easy to hear.


** Such and effect would be extremely easy to measure

It just don't exist when musical programme signals are being reproduced.


> It has some rather interesting implications about feedback,


** ******** it does.


> In "The Audio Critic," Vol 2, #2, 1979, p 37, Peter Aczel said Otala's
> technical paper was to be delivered on Feb. 25, 1980,


** That was a very long time ago - ****WIT.



........ Phil

[Phil]

Phil Allison wrote:
> "Phil"
> Andre Jute 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 ****.
>>>
>>
>>Pretty much what Patrick said, although I need to reply in the original
>>thread. What Matti Otala PROVED --
>
>
>
> ** Otala never proved one, single commercial hi-fi amp suffered from TIM in
> a way that was audible.
>
> Many others have proved conclusively that TIM ( ad his cousin SID) is a
> furphy.

Could you name an article showing that slewing induced distortions do
not exist? I can use an op-amp with 1 V per millisecond maximum slew
rate with no problems with signals at 10 V per millisecond? Surely
someone as intelligent as yourself (although it pains me to admit it)
wouldn't use that old, tired, debating trick of throwing out a "general
criticism without any supporting examples."


>
>
>
>>and Dr. Ottala was up there with Richard Heyser, not just a professor, but
>>the Director of the Technical Research Center of Finland, and the guy who
>>published many of the original papers on TIM (transient Intermodulation
>>Distortion), so what he said should at least *intially* be taken seriously
>
>
>
> ** It was - then got utterly debunked by others in the field wordwide.
>
> The debunking unfortunately did get the NOT the same publicity as Otala's
> hypothesis.
>
> So, ignorant ****WITS like you never heard about it.
>
>
>
> -- was that the
>
>>amplitude distortions of the open loop are transformed into phase
>>distortions of the closed loop, where the low frequency signals phase
>>modulate the high frequency signals. I *think* this means that the high
>>frequency signals move back and forward in time in the presense of low
>>frequency signals, something that is actually quite difficult to measure,
>>although all too easy to hear.
>
>
>
> ** Such and effect would be extremely easy to measure

Here I am genuinely curious; how would you measure it?

Phil
>
> It just don't exist when musical programme signals are being reproduced.
>
>
>
>>It has some rather interesting implications about feedback,
>
>
>
> ** ******** it does.
>
>
>
>>In "The Audio Critic," Vol 2, #2, 1979, p 37, Peter Aczel said Otala's
>>technical paper was to be delivered on Feb. 25, 1980,
>
>
>
> ** That was a very long time ago - ****WIT.
>
>
>
> ....... Phil
>
>

[Eeyore]

Phil wrote:

> Phil Allison wrote:
> > "Phil"
> > Andre Jute 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 ****.
> >>
> >>Pretty much what Patrick said, although I need to reply in the original
> >>thread. What Matti Otala PROVED --
> >
> >
> > ** Otala never proved one, single commercial hi-fi amp suffered from TIM in
> > a way that was audible.
> >
> > Many others have proved conclusively that TIM ( ad his cousin SID) is a
> > furphy.
>
> Could you name an article showing that slewing induced distortions do
> not exist? I can use an op-amp with 1 V per millisecond maximum slew
> rate with no problems with signals at 10 V per millisecond?

Eh ?


> Surely
> someone as intelligent as yourself (although it pains me to admit it)
> wouldn't use that old, tired, debating trick of throwing out a "general
> criticism without any supporting examples."

Firstly your slew rate figures are surely V/us ( microsecond )

For any sinewave ( see Fourier theory for applicability ) the max slew rate ( at
zero crossing btw ) is 2.pi.f.Vpeak.

For a 20kHz signal of say 2V peak amplitude that means a slew rate of 0.25 V/us
! Even a rubbish 741 or 1458 can manage that !

Given that modern audio op-amps are capable of slew rates of ~ 10V/us - you're
never even remotely close to slew limited anything.

Graham

[Phil]

Eeyore wrote:
>
> Phil wrote:
>
>
>>Phil Allison wrote:
>>
>>>"Phil"
>>> Andre Jute 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 ****.
>>>>
>>>>Pretty much what Patrick said, although I need to reply in the original
>>>>thread. What Matti Otala PROVED --
>>>
>>>
>>>** Otala never proved one, single commercial hi-fi amp suffered from TIM in
>>>a way that was audible.
>>>
>>> Many others have proved conclusively that TIM ( ad his cousin SID) is a
>>>furphy.
>>
>>Could you name an article showing that slewing induced distortions do
>>not exist? I can use an op-amp with 1 V per millisecond maximum slew
>>rate with no problems with signals at 10 V per millisecond?
>
>
> Eh ?
>
>
>
>>Surely
>>someone as intelligent as yourself (although it pains me to admit it)
>>wouldn't use that old, tired, debating trick of throwing out a "general
>>criticism without any supporting examples."
>
>
> Firstly your slew rate figures are surely V/us ( microsecond )

No, I'm making a point that, contrary to what Phil said, slew induced
distortion can indeed be a problem.
>
> For any sinewave ( see Fourier theory for applicability ) the max slew rate ( at
> zero crossing btw ) is 2.pi.f.Vpeak.
>
> For a 20kHz signal of say 2V peak amplitude that means a slew rate of 0.25 V/us
> ! Even a rubbish 741 or 1458 can manage that !
>
> Given that modern audio op-amps are capable of slew rates of ~ 10V/us - you're
> never even remotely close to slew limited anything.
>
> Graham

Well, remember, the maximum slew rate found in audio signals is much
greater than what a theoretical 20 KHz signal is going to supply, and
not all power amps, with their big, slow, output transistors, are going
to be as fast as even a 741. Plus, the point of Matti's work is that
problems begin to appear at all levels below the theoretical
"breakthrough" point of TIM/SID. In any case, the topic here is not
whether most amps have sufficient slew rate -- I assume that *most* good
amps do -- but rather about Otala's proof that a feedback amp's
"correction" of an amplitude distortion of the open loop phase shifts
the high frequency components in the closed loop. I am currently
discussing this in the "Negative Feedback in Triodes: The Logical and
Experimental Proof" thread from 8/15, so if you're interested, look
there (articles posted on 9/6). Phil Allison had a "response" here --
his usual slams and blams with no supporting evidence -- but I actually
would like to see his simple test that can show whether low frequency
signals in a feedback amp do or do not cause high frequency phase
shifting, as it would be useful test, and I'm having a hard time coming
up with a simple way to test that myself. Apparently, Otala incorporated
a lot of ideas/solutions into his Citation XX power amp, and maybe, if I
can find papers by him on that amp, there will be some useful
information and tests there, but if PA can come up with something in the
meantime, hell that's fine by me! He'll probably think of something
really simple and easy, and then refuse to tell me, the ****head ...

Anyway, what PA was saying/yelling is that feedback amps DO NOT EITHER
CAUSE PHASE SHIFTING OF THE HIGH FREQUENCIES LIKE THAT DUMMY DR. OTALA
SAID! My response was simply to ask whether (1) he knew of references
that would back up his claim, that Otala's analysis was flawed, and (2)
whether he knew of a good, simple test that can be used to test whether
LF signals in a feedback amp cause phase shifting of the HF signals,
like Otala said they do.

Phil

To email me directly, cut off my head
>
>

[Eeyore]

Phil wrote:

> Eeyore wrote:
> >
> > For any sinewave ( see Fourier theory for applicability ) the max slew rate ( at
> > zero crossing btw ) is 2.pi.f.Vpeak.
> >
> > For a 20kHz signal of say 2V peak amplitude that means a slew rate of 0.25 V/us
> > ! Even a rubbish 741 or 1458 can manage that !
> >
> > Given that modern audio op-amps are capable of slew rates of ~ 10V/us - you're
> > never even remotely close to slew limited anything.
> >
> > Graham
>
> Well, remember, the maximum slew rate found in audio signals is much
> greater than what a theoretical 20 KHz signal is going to supply,

Utter drivel.

Learn some science before posting such ********.

bye bye.

Graham

[Phil]

Eeyore wrote:
>
> Phil wrote:
>
>
>>Eeyore wrote:
>>
>>>For any sinewave ( see Fourier theory for applicability ) the max slew rate ( at
>>>zero crossing btw ) is 2.pi.f.Vpeak.
>>>
>>>For a 20kHz signal of say 2V peak amplitude that means a slew rate of 0.25 V/us
>>>! Even a rubbish 741 or 1458 can manage that !
>>>
>>>Given that modern audio op-amps are capable of slew rates of ~ 10V/us - you're
>>>never even remotely close to slew limited anything.
>>>
>>>Graham
>>
>>Well, remember, the maximum slew rate found in audio signals is much
>>greater than what a theoretical 20 KHz signal is going to supply,
>
>
> Utter drivel.
>
> Learn some science before posting such ********.
>
> bye bye.
>
> Graham
>
I'll tell you what, why don't you take one point that you can attack,
ignore everything else, and then put out yet another unsupported
criticism. In audio, where you have a huge mixture of signals, the
waveforms periodically add together, momentarily increasing the slew
rate over what a typical -- read, very small amplitude -- audio 20 KHz
signal would have. Do you disagree with that? Would you like to state
here, for the public record, that you think that when several signals
are mixed, that there are no momentary peaks in slew rate which exceed
the maximum slew rate found in individual signals? By all means, show
everyone here how well you think, and reason, and how much you actually
understand about audio. Oh, BY THE WAY, do you have anything intelligent
and useful to say about the rest of my comments? Useless cheap shots do
not qualify ...

Phil

[Phil Allison]

"Phil"
>
>> ** Otala never proved one, single commercial hi-fi amp suffered from TIM
>> in a way that was audible.
>>
>> Many others have proved conclusively that TIM ( and his cousin SID) is
>> a furphy.
>
> Could you name an article showing that slewing induced distortions do not
> exist?



** Try to comprehend what you read - you ****ing MORON.





........ Phil

[ScottW]

"Phil" > wrote in message
...
> Eeyore wrote:
>>
>> Phil wrote:
>>
>>
>>>Eeyore wrote:
>>>
>>>>For any sinewave ( see Fourier theory for applicability ) the max slew rate
>>>>( at
>>>>zero crossing btw ) is 2.pi.f.Vpeak.
>>>>
>>>>For a 20kHz signal of say 2V peak amplitude that means a slew rate of 0.25
>>>>V/us
>>>>! Even a rubbish 741 or 1458 can manage that !
>>>>
>>>>Given that modern audio op-amps are capable of slew rates of ~ 10V/us -
>>>>you're
>>>>never even remotely close to slew limited anything.
>>>>
>>>>Graham
>>>
>>>Well, remember, the maximum slew rate found in audio signals is much
>>>greater than what a theoretical 20 KHz signal is going to supply,
>>
>>
>> Utter drivel.
>>
>> Learn some science before posting such ********.
>>
>> bye bye.
>>
>> Graham
>>
> I'll tell you what, why don't you take one point that you can attack, ignore
> everything else, and then put out yet another unsupported criticism. In audio,
> where you have a huge mixture of signals, the waveforms periodically add
> together, momentarily increasing the slew rate over what a typical -- read,
> very small amplitude -- audio 20 KHz signal would have. Do you disagree with
> that?

If you have a signal with too much amplitude for your amp,
its called clipping.

ScottW

[Phil Allison]

"Phil"

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


** The simplest test shows this is UTTERLY FALSE.



> Plus, the point of Matti's work is that problems begin to appear at all
> levels below the theoretical "breakthrough" point of TIM/SID.


** Shame no-one could find evidence of this in commercial amplifiers.


> In any case, the topic here is not whether most amps have sufficient slew
> rate -- I assume that *most* good amps do -- but rather about Otala's
> proof that a feedback amp's "correction" of an amplitude distortion of the
> open loop phase shifts the high frequency components in the closed loop.


** ********.

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.

Dynamic phase shift in hi-fi amps and pre-amps is a myth - closely related
to the old slew rate myth.

Remember TIM and SID ???

Long dead now, poor fellows.






....... Phil

[Phil]

Well Andre, it looks like it's you and me, since everyone else has
either pussied out on me (Phil Asshole, Graham), dealt with other
issues, although probably honestly (Scott), or is waiting for further
developments (Patrick). I went by the UT library today, and looked
through several years of JAES, 1980 onward, but only found one article
by Matti Otala. I think maybe he published some papers in IEEE, I'll
have to check. However, in the Jan. 1980 JAES issue, there is an article
by Vanderkooy and Lip****z called "Feedforward Error Correction in Power
Amplifiers" that looks *very* interesting! I haven't thoroughly looked
at it yet, but they review all the various types of feedforward schemes,
starting with the one invented by Harold Black in 1923! They also review
the Quad 405, which is a different type of feedforward, which I can
state from personal experience sounds pretty bad compared to any decent
tube amp.

My interest in this is due to my initial conclusion from Otala's paper,
namely that a method of feedback -- which we have to have if using solid
state devices to obtain low output impedance-- that is quite different
from the usual feedback scheme, would avoid the dynamic phase shifting
problem. I had worked out an obvious overall topology, which turned out
to be almost exactly the same as Black's feedforward scheme of 1923!
Whoa ... Briefly, the problem as I see it, is that when a standard
feedback amp with, say, 40 dB of feedback is initially hit with a step
signal, the initial output is 100 times too large as seen by the
feedback circuit. Note that even if the gain is constant, and the load
is a perfect resistor of just the right size to give exactly 100 x open
loop, the feedback loop sees an ERROR of 99%. This, I suspect, is what
kills high feedback amplifiers. It would be one thing if only the minor
errors due to slight gain variations in the transistors and impedance
variations in the load were converted in to phase distortion, but as far
as I can see, the feedback error loop cannot possibly distinguish
between those minor errors, and the 100 x gain error that is inherent to
the loop! In other words, the excess gain that is used to obtain 40 dB
of feedback is itself seen as an error, and converted into phase
distortion, just like the "real" errors in the load and output devices.
Of course, this error only exists when a signal is present, but every
perfect sine wave signal must be 99% corrected, and since this
"correction" is actually a *conversion* into phase distortion, we wind
up with the horrid sound that high feedback SS amps so often have.

The alternative, which is basically Black's original feedforward amp
design, is to have one amp that is basically just a transconductance
amp, x amps out per y volts in, and the output voltage from this amp is
then compared to the input to produce an error signal. This signal is
then sent to a second, parallel amp, whose output is then added to the
first amp's output. Ideally, you have two time delay circuits to offset
the delay through the two amps, and it might be possible to use a
parallel resistor in the output to supply some of the damping, but these
are mostly details. The main point is that almost all of the
"correction" signal would in fact be due to load variations (the second
amp's gain is adjusted to match the first amp's gain), and *not* from
the excess gain of the feedback amp, thereby greatly reducing the amount
of dynamic phase distortion. Furthermore, since this feedback signal can
"concentrate on the true errors" (whereas a normal feedback amp
"concentrates" 98% to 99% on the excess gain, and only 1% to 2% on the
true errors), it may be much more effective at counteracting the errors
from the inherent crappy SS capacitors that come with any SS device, and
also the SS thermal variations, which are much greater than the thermal
variations of tubes. These capacitance and thermal defects are, I
suspect, the other reason (in addition to feedback phase distortion) why
power SS amps seem to be worse at amplifying a mixture of high and low
amplitude signals -- i.e., music -- than tubes. These errors "mess up"
the low level signals, causing SS amps to have less life and air than
tube amps. Finally, the "error amp" in Black's feedforward design, which
sends a signal to the second parallel amp, can be a vacuum tube, and
since this *is* able to amplify high and low signals, it can more easily
correct the destruction of the low level signals by the main amps! In
other words, we can use a vacuum tube to insure quality amplification of
the entire music signal, high and low level, and use this to correct the
inability of power SS amps to do the same. In a normal feedback amp this
would be largely impossible, since the typical level of 26 dB of
feedback constantly "corrects" 95% of the output, converting this
"error" (which is just the normal open loop gain) into phase distortion,
something which normally would overwhelm the ability of a tube to
restore low level information.

Of course, I don't know if this will actually work, but in theory, it
sounds VERY promising! Now, if we can just convince a few people to try
my improved double-blind test (which mimics the actions of the Boulder
amp people, only at rather higher speed) to select those components that
really are capable of greater resolution, and then "dumb-down" the
results until it is musical, we may have a truly musical, relatively
inexpensive, almost all SS amp! If we could just get some low output
impedance (2 ohms) power JFETS to go with it ...

Phil

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
>

[Eeyore]

Phil wrote:

> Eeyore wrote:
> >
> > Phil wrote:
> >
> >
> >>Eeyore wrote:
> >>
> >>>For any sinewave ( see Fourier theory for applicability ) the max slew rate ( at
> >>>zero crossing btw ) is 2.pi.f.Vpeak.
> >>>
> >>>For a 20kHz signal of say 2V peak amplitude that means a slew rate of 0.25 V/us
> >>>! Even a rubbish 741 or 1458 can manage that !
> >>>
> >>>Given that modern audio op-amps are capable of slew rates of ~ 10V/us - you're
> >>>never even remotely close to slew limited anything.
> >>>
> >>>Graham
> >>
> >>Well, remember, the maximum slew rate found in audio signals is much
> >>greater than what a theoretical 20 KHz signal is going to supply,
> >
> >
> > Utter drivel.
> >
> > Learn some science before posting such ********.
> >
> > bye bye.
> >
> > Graham
> >
> I'll tell you what, why don't you take one point that you can attack,
> ignore everything else, and then put out yet another unsupported
> criticism. In audio, where you have a huge mixture of signals, the
> waveforms periodically add together, momentarily increasing the slew
> rate over what a typical -- read, very small amplitude -- audio 20 KHz
> signal would have. Do you disagree with that?

Yes.

It's utter ********.

A 4V pk-pk signal is not small amplitude either btw. It's typical of pro-audio 'line
level' which is why I chose it.

Here's a 'big' signal. 15V peak. That's nearly 2V/us @ 20kHz. That's why you shouldn't
use 741s for audio btw.


> Would you like to state
> here, for the public record, that you think that when several signals
> are mixed, that there are no momentary peaks in slew rate which exceed
> the maximum slew rate found in individual signals?

There aren't. If you had a scientific education You'd understand.


> By all means, show
> everyone here how well you think, and reason, and how much you actually
> understand about audio. Oh, BY THE WAY, do you have anything intelligent
> and useful to say about the rest of my comments? Useless cheap shots do
> not qualify ...

Learn some science before posting such ********.

Graham

[Eeyore]

Phil Allison wrote:

> "Phil"
>
> >
> > Well, remember, the maximum slew rate found in audio signals is much
> > greater than what a theoretical 20 KHz signal is going to supply,
>
> ** The simplest test shows this is UTTERLY FALSE.

Mr Fourier would concur with PA too.

Graham

[Sander deWaal]

Phil > said:

>Well Andre, it looks like it's you and me, since everyone else has
>either pussied out on me (Phil Asshole, Graham), dealt with other
>issues, although probably honestly (Scott), or is waiting for further
>developments (Patrick). I went by the UT library today, and looked
>through several years of JAES, 1980 onward, but only found one article
>by Matti Otala. I think maybe he published some papers in IEEE, I'll
>have to check. However, in the Jan. 1980 JAES issue, there is an article
>by Vanderkooy and Lip****z called "Feedforward Error Correction in Power
>Amplifiers" that looks *very* interesting! I haven't thoroughly looked
>at it yet, but they review all the various types of feedforward schemes,
>starting with the one invented by Harold Black in 1923! They also review
>the Quad 405, which is a different type of feedforward, which I can
>state from personal experience sounds pretty bad compared to any decent
>tube amp.


That you didn't find much after 1980, is because mr. Otala published
his findings in the early '70s.

At that time, the problems as described by him, were a reality in may
commercial amplifiers, and we've learned a lot since then.

Later, people like Daugherty and Greiner proved that (large factors
of) feedback isn't the evil that may seem to think it is, and that it
doesn't necessarily generate additional distortion, when applied
correctly.

I happen to think that Otala has played a major role in getting more
insight in what happens in an amplifier stage with feedback.

Others after him corrected and modified his findings.


There are more ways that lead to Rome.


BTW a modified 405-II can sound very good, at least to these ears.

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

[Patrick Turner]

Phil wrote:

> Eeyore wrote:
> >
> > Phil wrote:
> >
> >
> >>Phil Allison wrote:
> >>
> >>>"Phil"
> >>> Andre Jute 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 ****.
> >>>>
> >>>>Pretty much what Patrick said, although I need to reply in the original
> >>>>thread. What Matti Otala PROVED --
> >>>
> >>>
> >>>** Otala never proved one, single commercial hi-fi amp suffered from TIM in
> >>>a way that was audible.
> >>>
> >>> Many others have proved conclusively that TIM ( ad his cousin SID) is a
> >>>furphy.
> >>
> >>Could you name an article showing that slewing induced distortions do
> >>not exist? I can use an op-amp with 1 V per millisecond maximum slew
> >>rate with no problems with signals at 10 V per millisecond?
> >
> >
> > Eh ?
> >
> >
> >
> >>Surely
> >>someone as intelligent as yourself (although it pains me to admit it)
> >>wouldn't use that old, tired, debating trick of throwing out a "general
> >>criticism without any supporting examples."
> >
> >
> > Firstly your slew rate figures are surely V/us ( microsecond )
>
> No, I'm making a point that, contrary to what Phil said, slew induced
> distortion can indeed be a problem.
> >
> > For any sinewave ( see Fourier theory for applicability ) the max slew rate ( at
> > zero crossing btw ) is 2.pi.f.Vpeak.
> >
> > For a 20kHz signal of say 2V peak amplitude that means a slew rate of 0.25 V/us
> > ! Even a rubbish 741 or 1458 can manage that !
> >
> > Given that modern audio op-amps are capable of slew rates of ~ 10V/us - you're
> > never even remotely close to slew limited anything.
> >
> > Graham
>
> Well, remember, the maximum slew rate found in audio signals is much
> greater than what a theoretical 20 KHz signal is going to supply, and
> not all power amps, with their big, slow, output transistors, are going
> to be as fast as even a 741.

Not all output bjts are big and slow.
Some do however dislike turning OFF quickly and some display the truly
horrible habit of cross conduction at HF, ie, the two bjts in a typical complementary
pair
are BOTH turned on during a wave cycle during large signal excursions at above 10kHz,
and the power supply has to supply a lot more current that is simply passing from rail
to rail
and its hang onto your hat time for the ride.

> Plus, the point of Matti's work is that
> problems begin to appear at all levels below the theoretical
> "breakthrough" point of TIM/SID. In any case, the topic here is not
> whether most amps have sufficient slew rate -- I assume that *most* good
> amps do -- but rather about Otala's proof that a feedback amp's
> "correction" of an amplitude distortion of the open loop phase shifts
> the high frequency components in the closed loop.

Both amplitude distortions and phase distortions of the open loop
response are BOTH corrected by the NFB.
Typical open loop phase lag in open loop at 20kHz is 90 degrees, and the 40dB of
applied global NFB
at 20kHz reduces this typically to less than 5 degrees.

> I am currently
> discussing this in the "Negative Feedback in Triodes: The Logical and
> Experimental Proof" thread from 8/15, so if you're interested, look
> there (articles posted on 9/6). Phil Allison had a "response" here --
> his usual slams and blams with no supporting evidence -- but I actually
> would like to see his simple test that can show whether low frequency
> signals in a feedback amp do or do not cause high frequency phase
> shifting, as it would be useful test, and I'm having a hard time coming
> up with a simple way to test that myself.

Just apply 70Hz and 5kHz signals to the input of an amp
in a 4:1 ratio.
Filter out all below 1kHz from the output signal.
Then you will see what the effect of the 70Hz large signal is upon the
fidelity of the 5kHz signal and whether there is any phase modulation
in addition to the expected intermodulation.
With most well made SS high NFB amps, the IMD is not visible on the CRO
and a careful peak detector must be used to measure amplitude variations in the 5kHz,
or else filter out the IMD products at 4,930Hz and 5,070Hz.




> Apparently, Otala incorporated
> a lot of ideas/solutions into his Citation XX power amp, and maybe, if I
> can find papers by him on that amp, there will be some useful
> information and tests there, but if PA can come up with something in the
> meantime, hell that's fine by me! He'll probably think of something
> really simple and easy, and then refuse to tell me, the ****head ...

But all these investigations have been done many times before.

What exactly do you hope to gain by goading the ungoadables on the group
to find out what you should be willing to find out for yourself?

Do you suspect to find some hitherto unused uninvented techniques of making
amplifiers perform better?

>
>
> Anyway, what PA was saying/yelling is that feedback amps DO NOT EITHER
> CAUSE PHASE SHIFTING OF THE HIGH FREQUENCIES LIKE THAT DUMMY DR. OTALA
> SAID! My response was simply to ask whether (1) he knew of references
> that would back up his claim, that Otala's analysis was flawed, and (2)
> whether he knew of a good, simple test that can be used to test whether
> LF signals in a feedback amp cause phase shifting of the HF signals,
> like Otala said they do.

Be like me, find out by building one's own test gear and testing.
It took me months to do it all but after reading all the conflicting opinions about
all this in
Electronics World copies from the 1970s to 1980s BEFORE the internet was mainstream,
I decided to look myself at what happened in amps that i should be worried about.

Patrick Turner.

>
>
> Phil
>
> To email me directly, cut off my head
> >
> >

[Phil Allison]

"Sander de******"
>
> That you didn't find much after 1980, is because mr. Otala published
> his findings in the early '70s.


** Otala never published any actual "findings" whatever.

His wacky and always controversial hypotheses briefly polluted the technical
press in the mid and late 70s, actually.

Reminds me a lot of the bizarre "Cold Fusion " fiasco.

How embarrassment.



> At that time, the problems as described by him, were a reality in may
> commercial amplifiers, and we've learned a lot since then.


** Absolute ******** !!!!!!!!!


> Later, people like Daugherty and Greiner proved that (large factors
> of) feedback isn't the evil that may seem to think it is, and that it
> doesn't necessarily generate additional distortion, when applied
> correctly.


** Never has - even when applied in time honoured, traditional ways.


> I happen to think that Otala has played a major role in getting more
> insight in what happens in an amplifier stage with feedback.


** Highly doubtful that a room temp cretin like * YOU* thinks at all.

Just reacts to its environment - like any slimy reptile.



> Others after him corrected and modified his findings.


** ****ed on them from a VERY GREAT height and buried them, basically.


> There are more ways that lead to Rome.


** Depends how completely LOST you are.


> BTW a modified 405-II can sound very good, at least to these ears.


** So will an unmodified one & and an original 405.

Now -

**** the HELL OFF

Bloody Jerk OFF !!!!!!!!!!





........ Phil

[Patrick Turner]

Phil wrote:

> Eeyore wrote:
> >
> > Phil wrote:
> >
> >
> >>Eeyore wrote:
> >>
> >>>For any sinewave ( see Fourier theory for applicability ) the max slew rate ( at
> >>>zero crossing btw ) is 2.pi.f.Vpeak.
> >>>
> >>>For a 20kHz signal of say 2V peak amplitude that means a slew rate of 0.25 V/us
> >>>! Even a rubbish 741 or 1458 can manage that !
> >>>
> >>>Given that modern audio op-amps are capable of slew rates of ~ 10V/us - you're
> >>>never even remotely close to slew limited anything.
> >>>
> >>>Graham
> >>
> >>Well, remember, the maximum slew rate found in audio signals is much
> >>greater than what a theoretical 20 KHz signal is going to supply,
> >
> >
> > Utter drivel.
> >
> > Learn some science before posting such ********.
> >
> > bye bye.
> >
> > Graham
> >
> I'll tell you what, why don't you take one point that you can attack,
> ignore everything else, and then put out yet another unsupported
> criticism. In audio, where you have a huge mixture of signals, the
> waveforms periodically add together, momentarily increasing the slew
> rate over what a typical -- read, very small amplitude -- audio 20 KHz
> signal would have. Do you disagree with that? Would you like to state
> here, for the public record, that you think that when several signals
> are mixed, that there are no momentary peaks in slew rate which exceed
> the maximum slew rate found in individual signals? By all means, show
> everyone here how well you think, and reason, and how much you actually
> understand about audio. Oh, BY THE WAY, do you have anything intelligent
> and useful to say about the rest of my comments? Useless cheap shots do
> not qualify ...
>
> Phil

But the worst case additions of many different varying frequencies and amplitudes
of a musical signal cannot give rise to a faster rise time than that of a full power
sine wave signal at the frequency limit of the music bandwidth.
This bandwidth is about 20 kHz these days, and whatever you do with other waves below
this F
the rise time will never be faster than that in a 20kHz full power sine wave.
If anything happens at a faster rate, ie, the slope of the wave graph is steeper
than that of a 20kHz wave then there are higher F present which are above 20kHz.

If what you are suggesting is possible, then such manifestations of higher frequencies
above 20kHz
could easily be filtered out and proved to exist.

Foe example if the amp produces 2H and 3H of say 20kHz, then indeed the 40hHz and 60kHz

would become real, and the IMD product between say 8kHz and 18kHz of 26kHz would become

real, providing the amp has the capacity to pass the higher F.
Usually most amps can do this because such spuriae above 20kHz are low in level.

Patrick Turner.

[Arny Krueger]

"Phil" > wrote in message

> Eeyore wrote:

>> For a 20kHz signal of say 2V peak amplitude that means a
>> slew rate of 0.25 V/us ! Even a rubbish 741 or 1458 can
>> manage that !

Agreed.

>> Given that modern audio op-amps are capable of slew
>> rates of ~ 10V/us - you're never even remotely close to
>> slew limited anything.

Agreed.

I was just looking at the specs for a modern op amp that I think TI or
National is trying to popularize, and the SR was more like 100 V/uS

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

OK, let's totally lose our minds and say that it is 10 times as much. That
makes 2.5 V/uS, which is still only 25% of the capabilities of ca.-1980s op
amp.

BTW here's a hint - the slew rate at the output of any digital player is
limited to voltages along the lines of what Graham came up with in his
calculations. Why we laugh when people "upgrade" the outputs of CD players
by putting in op amps with rediculously high slew rates? ;-)

> and not all power amps, with
> their big, slow, output transistors, are going to be as
> fast as even a 741.

Wrong again. It's hard to find a modern power amp that slews even just 10
times faster than a 741. Most do far better than that.

>Plus, the point of Matti's work is
> that problems begin to appear at all levels below the
> theoretical "breakthrough" point of TIM/SID.

See my previous ludicrously tough example that included a 10:1 safety margin
and was still hitting only 25% of the capabilities of 25-year-old
technology.

>In any case,
> the topic here is not whether most amps have sufficient
> slew rate -- I assume that *most* good amps do -- but
> rather about Otala's proof that a feedback amp's
> "correction" of an amplitude distortion of the open loop
> phase shifts the high frequency components in the closed
> loop.

Which is wrong.

>I am currently discussing this in the "Negative
> Feedback in Triodes: The Logical and Experimental Proof"
> thread from 8/15, so if you're interested, look there
> (articles posted on 9/6).

I can't bear to look at that thread again Phil, because you took such a
merciless licking from just about everybody.

[Sander deWaal]

"Phil Allison" > said:


>"Sander de******"


How did you find out? ;-)


>> That you didn't find much after 1980, is because mr. Otala published
>> his findings in the early '70s.


>** Otala never published any actual "findings" whatever.


Look up some AES papers some time.


>His wacky and always controversial hypotheses briefly polluted the technical
>press in the mid and late 70s, actually.

>Reminds me a lot of the bizarre "Cold Fusion " fiasco.

>How embarrassment.


>> At that time, the problems as described by him, were a reality in may
>> commercial amplifiers, and we've learned a lot since then.


> ** Absolute ******** !!!!!!!!!


We've learned *nothing* since the '70s?

Surprising, and not according to my findings.


>> Later, people like Daugherty and Greiner proved that (large factors
>> of) feedback isn't the evil that may seem to think it is, and that it
>> doesn't necessarily generate additional distortion, when applied
>> correctly.


>** Never has - even when applied in time honoured, traditional ways.


Many seem to disagree, and not only simple techies like me.


>> I happen to think that Otala has played a major role in getting more
>> insight in what happens in an amplifier stage with feedback.


>** Highly doubtful that a room temp cretin like * YOU* thinks at all.


> Just reacts to its environment - like any slimy reptile.


>> Others after him corrected and modified his findings.


>** ****ed on them from a VERY GREAT height and buried them, basically.


In PA-speak, probably.


>> There are more ways that lead to Rome.


> ** Depends how completely LOST you are.


>> BTW a modified 405-II can sound very good, at least to these ears.


> ** So will an unmodified one & and an original 405.

> Now -

> **** the HELL OFF

> Bloody Jerk OFF !!!!!!!!!!


>....... Phil



Are you feeling well, Phil?
Your tone isn't that harsh and shrill as usual.

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

[Phil Allison]

"Sander de******"


** Highly doubtful that a room temp cretin like * YOU* thinks at all.

Just reacts to its environment , slowly - like any SLIMY reptile.

Now -

**** the HELL OFF

YOU ****wit Audiophool JERK !!!!!!!!!






....... Phil

[Patrick Turner]

Sander deWaal wrote:

> Phil > said:
>
> >Well Andre, it looks like it's you and me, since everyone else has
> >either pussied out on me (Phil Asshole, Graham), dealt with other
> >issues, although probably honestly (Scott), or is waiting for further
> >developments (Patrick). I went by the UT library today, and looked
> >through several years of JAES, 1980 onward, but only found one article
> >by Matti Otala. I think maybe he published some papers in IEEE, I'll
> >have to check. However, in the Jan. 1980 JAES issue, there is an article
> >by Vanderkooy and Lip****z called "Feedforward Error Correction in Power
> >Amplifiers" that looks *very* interesting! I haven't thoroughly looked
> >at it yet, but they review all the various types of feedforward schemes,
> >starting with the one invented by Harold Black in 1923! They also review
> >the Quad 405, which is a different type of feedforward, which I can
> >state from personal experience sounds pretty bad compared to any decent
> >tube amp.
>
> That you didn't find much after 1980, is because mr. Otala published
> his findings in the early '70s.
>
> At that time, the problems as described by him, were a reality in may
> commercial amplifiers, and we've learned a lot since then.
>
> Later, people like Daugherty and Greiner proved that (large factors
> of) feedback isn't the evil that may seem to think it is, and that it
> doesn't necessarily generate additional distortion, when applied
> correctly.

The only time large amounts of additional distortion harmonic or
intermodulation
harmonic products are generated in a FB amp are when the

1, The open loop THD and IMD is high, perhaps 10% and before clipping is
occuring,

2, the open loop bandwidth is poor, allowing higher F distortion products to
not be reduced by the FB
because applied FB is dependant on open loop gain and phase shift.

3, the open loop phase shift is poor.

4, the amount of NFB is small, tyically less than 14dB.

There have been several articles in Wireless World and Electrincs World
where the authors have explored the phenomena of applied NFB around a rather
non linear amp.

Where say 3H is abundant in the open loop thd, when mild NFB is used there is
2H and 4H
generated by IMD process because the 3H fed back is modulated by the
fundemental to make the sum and difference
IMD products of 2H and 4H.

However, these additional distortion products are low in level, but are
reduced if enough NFB is
applied and the bandwidth phase shift of the open loop permits stability.

So we have SS amps with typically 60 dB of applied global NFB at say 500Hz
which
is where the maximumm open loop gain is. the open loop -3dB point is at say
1kHz,
and at 10kHz the OLG is -20dB, so that only 40 dB of applied NFB is used at
10kHz but its
enough to reduce measured distortions of all kinds to triflingly small
levels.

The problem eith many old amps is that where you did try to test a full power
signal at
20kHz or above, the input stages had to perform serious electronic gymnastics
to
force the output stage to produce a level response, ie, the input stages
saturated,
and the sine wave at HF became a triangular wave, and limiting commenced
before full power and mid frequency clipping levels were reached.

Some tube amps are not imune to such ****e happening at HF.

SE amps using pentodes do have open loop problems of high open loop THD and
IMD.
When used with only 10dB of global NFB the outcome is sonically not much
better
than with no NFB although at least the Rout has been reduced to about the
same as a triode
without NFB.

So with pentodes, one must use a lot of NFB to get anywhere good at least as
measurements go,
and still a large spray of extra harmonics are made and remain but at a low
level
when 20dB of NFB is used.
SE triodes when used without expecting too much average power, ie, less than
10% of the clipping power
will sound better than the pentode with mild NFB and the same max power
capability.
That's because the triode manages lower Rout than the pentode with too little
NFB and the
triode THD/IMD without loop NFB is less than the pentodes with mild NFB.

Whether the class A SE pentode with 20 dB loop NFB is better sounding than
the SE triode without NFB
is an often bitterly argued topic, but I have to say I prefer the sound of a
2A3 with
a paltry 6dB of NFB compared to a 6V6 or EL84 with same 4 watt maxima
and 20 dB of NFB.


>
> I happen to think that Otala has played a major role in getting more
> insight in what happens in an amplifier stage with feedback.
>
> Others after him corrected and modified his findings.
>
> There are more ways that lead to Rome.
>
> BTW a modified 405-II can sound very good, at least to these ears.

There is no accounting for taste.

Patrick Turner.

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

[Sander deWaal]

"Phil Allison" > said:


>"Sander de******"

>** Highly doubtful that a room temp cretin like * YOU* thinks at all.

> Just reacts to its environment , slowly - like any SLIMY reptile.

> Now -

> **** the HELL OFF

> YOU ****wit Audiophool JERK !!!!!!!!!

>...... Phil



Thanks Phil, for a moment there I was afraid that you were not well.
This post is just what I expected in the first place, thanks for
reassuring me that all is normal again!

How are your Quads doing these days BTW?

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

[Joseph Meditz]

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

[Phil Allison]

"Joseph Meditz" > wrote in message
ups.com...


** Groper Alert !

>
>> ** 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.
>>
>
> I say that this is precisely an acoustical frequency modulator



** It is an acoustic phase modulator.



> 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.


** Nope.




.......... Phil

[Phil Allison]

"Sander deWog******"


**** the HELL OFF

YOU ****wit Audiophool JERK !!!!!!!!!


....... Phil

[[email protected]]

On Thu, 7 Sep 2006 21:54:33 +1000, "Phil Allison" >
wrote:

>
>
>> Later, people like Daugherty and Greiner proved that (large factors
>> of) feedback isn't the evil that may seem to think it is, and that it
>> doesn't necessarily generate additional distortion, when applied
>> correctly.
>
>
>** Never has - even when applied in time honoured, traditional ways.
>

Now there is something I can agree with 100%...


Bob FlintsTone

[paul packer]

On Fri, 8 Sep 2006 10:43:58 +1000, "Phil Allison"
> wrote:

>
>"Sander deWog******"
>
>
> **** the HELL OFF
>
> YOU ****wit Audiophool JERK !!!!!!!!!
>
>
>...... Phil


Gee, Phil look at you---multi-tasking! And I thought you could only be
disgusting in one place at a time.

[Chris Hornbeck]

On Thu, 07 Sep 2006 13:40:14 +0200, Sander deWaal >
wrote:

>That you didn't find much after 1980, is because mr. Otala published
>his findings in the early '70s.

Right-e-o. He wants AES Rotterdam 22.2.1973, Jan Lohstroh
and Matti Otala "An Audio Amplifier for Ultimate Quality
Requirements", which rigorized the issues and proposed
(later universally accepted) changes to topology.


>At that time, the problems as described by him, were a reality in may
>commercial amplifiers, and we've learned a lot since then.
>
>Later, people like Daugherty and Greiner proved that (large factors
>of) feedback isn't the evil that may seem to think it is, and that it
>doesn't necessarily generate additional distortion, when applied
>correctly.

Also in American audio press Jung, Stevenson, and Todd wrote an
excellent "Overview of SID and TIM" in the Summer of 1979 _Audio_
magazines, which lead to the Spring 1980 _Audio_ articles by Cordell
"Another View of TIM".

Cordell showed clearly, and argued for, what Jung had implied,
that a sufficiently low level of THD at 20KHz (the number .02%
has become accepted) is enough to show that no TIM will exhibit
*with a bandlimited input signal*.

For output amplifiers, end of discussion. For input stages fed
un-bandwidth-limited signal, greater scrutiny is required.

Some common examples of input stages faced with larger than
"CD" bandwidth are microphone preamps, phono equalizers, and
D/A converter summing amps.

Much thanks, as always,

Chris Hornbeck
"Man is the measure of all things. Sigh.
Happy Ears!" -Al

[Ian Iveson]

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.

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.

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

Thanks for your input, Phil

cheers, Ian

[Arny Krueger]

"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.

[Phil]

Sander deWaal wrote:
> Phil > said:
>
>
>>Well Andre, it looks like it's you and me, since everyone else has
>>either pussied out on me (Phil Asshole, Graham), dealt with other
>>issues, although probably honestly (Scott), or is waiting for further
>>developments (Patrick). I went by the UT library today, and looked
>>through several years of JAES, 1980 onward, but only found one article
>>by Matti Otala. I think maybe he published some papers in IEEE, I'll
>>have to check. However, in the Jan. 1980 JAES issue, there is an article
>>by Vanderkooy and Lip****z called "Feedforward Error Correction in Power
>>Amplifiers" that looks *very* interesting! I haven't thoroughly looked
>>at it yet, but they review all the various types of feedforward schemes,
>>starting with the one invented by Harold Black in 1923! They also review
>>the Quad 405, which is a different type of feedforward, which I can
>>state from personal experience sounds pretty bad compared to any decent
>>tube amp.
>
>
>
> That you didn't find much after 1980, is because mr. Otala published
> his findings in the early '70s.
>
> At that time, the problems as described by him, were a reality in may
> commercial amplifiers, and we've learned a lot since then.
>
> Later, people like Daugherty and Greiner proved that (large factors
> of) feedback isn't the evil that may seem to think it is, and that it
> doesn't necessarily generate additional distortion, when applied
> correctly.
>
> I happen to think that Otala has played a major role in getting more
> insight in what happens in an amplifier stage with feedback.
>
> Others after him corrected and modified his findings.
>
>
> There are more ways that lead to Rome.
>
>
> BTW a modified 405-II can sound very good, at least to these ears.
>
The Quad I heard was not modified, so I couldn't say, although the one I
heard sounded very good unless compared to a good PP tube amp.

I want to emphasize that the original subject here is not what Phil
Allison implies, namely TIM or SID, but rather the question of whether
negative feedback causes audible problems even when there is no TIM.
I'll go ahead and quote the review of Otala's paper I gave in the other
thread, from "The Audio Critic," Vol 2, #2, p 37, regarding Matti
Otala's analysis of feedback (made after he, the editor Peter Aczel,
Mitch Cotter, Stew Hegeman, Andy Rappaport, Max Wilcox, and Bruce Zayde
had a "BS" session in TAC);

"The paper presents rigorous mathematical proof, for the most
generalized, all-inclusive case, that feedback cannot make amplifier
distortions go away; all it can do is to change one kind of distortion
into another. By the application of feedback, the amplitude
nonlinearities of the open loop are converted into phase nonlinearities
of the closed loop. That's all. The garbage cannot, by definition, be
made to disappear; it's simply swept into another corner. In the typical
feedback amplifier, the amplitude of the audio signal phase-modulates
the high-frequency components of the signal. Furthermore, any amplitude
intermodulation distortion in the open loop is converted into phase
intermodulation distortion in the closed loop. What about TIM, alias
SID? It turns out that it (he?) is a limit case of this
feedback-generated phase modulation effect, with all shades of gray
possible before the actual black eruption occurs. None of this shows up
on standard tests."

I still can't find this paper, despite several trips to the UT library,
but a little thought shows that it actually is consistent with much of
what you and the others ae saying. When an amp with, say, 40 dB of
feedback is hit with a step, the output initially has an "error" of 100
x, *independent* of any gain or load non-linearities, which must be
"corrected" by the feedback loop. For every single change in the input
voltage, the gain is off by a factor of 95 to 105, depending on gain and
load non-linearities, and this error must be corrected by the feedback
loop. Intuitively, it seems obvious that Otala's proof must in *some*
way be correct, that this constant "correction" must play havoc with low
level and high frequency signals. I don't think anyone would deny that,
given an amp with variable feedback followed by a pot to equalize the
overall gain, turning up the feedback will eventually make an amp that,
like the Crown preamp, will "bite your ears off," even if the amp never
gets into TIM territory or other obvious problems. The question is how
much of an effect does Otala's "dynamic phase shifting" have. Here
again, it seems obvious that part of the problem was the S-L-O-W power
transistors of the late '70's, when Otala's various articles were
written. I suspect that high speed devices reduce the problems created
by feedback, the amount of phase distortion produced, and of course
Otala himself came up with several ideas to reduce these effects in his
Citation XX design, although I also haven't been able to find any
literature on that design.

Nevertheless, it is a given, in my mind, that a very high open loop
gain, with its need to constantly "correct" every input signal by 99%
(in the case of 40 dB feedback), *regardless* of the inherent linearity
of the amp's devices and circuit, MUST cause problems for signals 60 dB
to 80 dB below the main signal, and perhaps also phase shift the high
frequency components, as Aczel's summary of Otala's paper states,
thereby robbing the circuit of much of its "life" and "air," the
criticisms one normally hears about high feedback amps, and also solid
state amps, in which the solid state capacitances and high thermal
variations also interfere with low level signals. This will not show up
as TIM or SID, unless the amp has been very poorly designed, and I'm
still not sure how one would measure it. My best guess has been to use a
20 Hz signal and a much smaller (-60 to -80 dB) 10 KHz signal, filter
out the 20 Hz signal from the output with a notch filter plus high pass
filter, and either look directly at the 10 KHz signal for signs of
distress, or filter it out with another notch filter, and see if phase
shifting causes "sidebands" to appear and disappear when the 20 Hz
signal is put in and out of the test.

Assuming that normal feedback causes problems -- and as Patrick says,
with low feedback and tubes it isn't too bad, but SS amps have more
problems and generally need more feedback -- it would be nice if we
could figure out a way to tremendously reduce the need for feedback to
"correct" every normal signal by 99% even when there is no device
distortion, meaning allow the feedback to "focus" *only* on actual
device and load non-linearities. Here is where Black's "feedforward"
circuit may allow for a real advance in SS amps, especially if tubes,
with their (generally) superior ability to handle a mix of high and low
level signals without messing up the low level information, are used to
provide the error signal. Properly applied, Black's feedforward scheme
(but not the feedforward designs by many others!) does exactly this, it
allows feedback to appear and affect the signal *only* when actual
deviations caused by device or load non-linearities appear. It may even
be possible to correct the effects of a typical transistor's parallel
capacitances -- which, being made of silicon, are of *very* poor quality
-- and thermal variations! Normally, this would be a "why waste the
time, just use tubes," situation, but good output transformers are
heavy, big, and expensive, and if the amps used in compact disk players,
as well as TV's, could be considerably improved, that would be nice! And
of course, inexpensive amps that sound very good are always in demand.

Phil

[Eeyore]

Phil wrote:

> Sander deWaal wrote:
> > Phil > said:
> >
> >
> >>Well Andre, it looks like it's you and me, since everyone else has
> >>either pussied out on me (Phil Asshole, Graham), dealt with other
> >>issues, although probably honestly (Scott), or is waiting for further
> >>developments (Patrick). I went by the UT library today, and looked
> >>through several years of JAES, 1980 onward, but only found one article
> >>by Matti Otala. I think maybe he published some papers in IEEE, I'll
> >>have to check. However, in the Jan. 1980 JAES issue, there is an article
> >>by Vanderkooy and Lip****z called "Feedforward Error Correction in Power
> >>Amplifiers" that looks *very* interesting! I haven't thoroughly looked
> >>at it yet, but they review all the various types of feedforward schemes,
> >>starting with the one invented by Harold Black in 1923! They also review
> >>the Quad 405, which is a different type of feedforward, which I can
> >>state from personal experience sounds pretty bad compared to any decent
> >>tube amp.
> >
> >
> >
> > That you didn't find much after 1980, is because mr. Otala published
> > his findings in the early '70s.
> >
> > At that time, the problems as described by him, were a reality in may
> > commercial amplifiers, and we've learned a lot since then.
> >
> > Later, people like Daugherty and Greiner proved that (large factors
> > of) feedback isn't the evil that may seem to think it is, and that it
> > doesn't necessarily generate additional distortion, when applied
> > correctly.
> >
> > I happen to think that Otala has played a major role in getting more
> > insight in what happens in an amplifier stage with feedback.
> >
> > Others after him corrected and modified his findings.
> >
> >
> > There are more ways that lead to Rome.
> >
> >
> > BTW a modified 405-II can sound very good, at least to these ears.
> >
> The Quad I heard was not modified, so I couldn't say, although the one I
> heard sounded very good unless compared to a good PP tube amp.
>
> I want to emphasize that the original subject here is not what Phil
> Allison implies, namely TIM or SID, but rather the question of whether
> negative feedback causes audible problems even when there is no TIM.
> I'll go ahead and quote the review of Otala's paper I gave in the other
> thread, from "The Audio Critic," Vol 2, #2, p 37, regarding Matti
> Otala's analysis of feedback (made after he, the editor Peter Aczel,
> Mitch Cotter, Stew Hegeman, Andy Rappaport, Max Wilcox, and Bruce Zayde
> had a "BS" session in TAC);
>
> "The paper presents rigorous mathematical proof, for the most
> generalized, all-inclusive case, that feedback cannot make amplifier
> distortions go away; all it can do is to change one kind of distortion
> into another. By the application of feedback, the amplitude
> nonlinearities of the open loop are converted into phase nonlinearities
> of the closed loop. That's all. The garbage cannot, by definition, be
> made to disappear; it's simply swept into another corner. In the typical
> feedback amplifier, the amplitude of the audio signal phase-modulates
> the high-frequency components of the signal. Furthermore, any amplitude
> intermodulation distortion in the open loop is converted into phase
> intermodulation distortion in the closed loop. What about TIM, alias
> SID? It turns out that it (he?) is a limit case of this
> feedback-generated phase modulation effect, with all shades of gray
> possible before the actual black eruption occurs. None of this shows up
> on standard tests."
>
> I still can't find this paper, despite several trips to the UT library,
> but a little thought shows that it actually is consistent with much of
> what you and the others ae saying. When an amp with, say, 40 dB of
> feedback is hit with a step, the output initially has an "error" of 100
> x, *independent* of any gain or load non-linearities, which must be
> "corrected" by the feedback loop. For every single change in the input
> voltage, the gain is off by a factor of 95 to 105, depending on gain and
> load non-linearities, and this error must be corrected by the feedback
> loop. Intuitively, it seems obvious that Otala's proof must in *some*
> way be correct, that this constant "correction" must play havoc with low
> level and high frequency signals. I don't think anyone would deny that,
> given an amp with variable feedback followed by a pot to equalize the
> overall gain, turning up the feedback will eventually make an amp that,
> like the Crown preamp, will "bite your ears off," even if the amp never
> gets into TIM territory or other obvious problems. The question is how
> much of an effect does Otala's "dynamic phase shifting" have. Here
> again, it seems obvious that part of the problem was the S-L-O-W power
> transistors of the late '70's, when Otala's various articles were
> written. I suspect that high speed devices reduce the problems created
> by feedback, the amount of phase distortion produced, and of course
> Otala himself came up with several ideas to reduce these effects in his
> Citation XX design, although I also haven't been able to find any
> literature on that design.
>
> Nevertheless, it is a given, in my mind, that a very high open loop
> gain, with its need to constantly "correct" every input signal by 99%
> (in the case of 40 dB feedback), *regardless* of the inherent linearity
> of the amp's devices and circuit, MUST cause problems for signals 60 dB
> to 80 dB below the main signal, and perhaps also phase shift the high
> frequency components, as Aczel's summary of Otala's paper states,
> thereby robbing the circuit of much of its "life" and "air," the
> criticisms one normally hears about high feedback amps, and also solid
> state amps, in which the solid state capacitances and high thermal
> variations also interfere with low level signals. This will not show up
> as TIM or SID, unless the amp has been very poorly designed, and I'm
> still not sure how one would measure it. My best guess has been to use a
> 20 Hz signal and a much smaller (-60 to -80 dB) 10 KHz signal, filter
> out the 20 Hz signal from the output with a notch filter plus high pass
> filter, and either look directly at the 10 KHz signal for signs of
> distress, or filter it out with another notch filter, and see if phase
> shifting causes "sidebands" to appear and disappear when the 20 Hz
> signal is put in and out of the test.
>
> Assuming that normal feedback causes problems -- and as Patrick says,
> with low feedback and tubes it isn't too bad, but SS amps have more
> problems and generally need more feedback -- it would be nice if we
> could figure out a way to tremendously reduce the need for feedback to
> "correct" every normal signal by 99% even when there is no device
> distortion, meaning allow the feedback to "focus" *only* on actual
> device and load non-linearities. Here is where Black's "feedforward"
> circuit may allow for a real advance in SS amps, especially if tubes,
> with their (generally) superior ability to handle a mix of high and low
> level signals without messing up the low level information, are used to
> provide the error signal. Properly applied, Black's feedforward scheme
> (but not the feedforward designs by many others!) does exactly this, it
> allows feedback to appear and affect the signal *only* when actual
> deviations caused by device or load non-linearities appear. It may even
> be possible to correct the effects of a typical transistor's parallel
> capacitances -- which, being made of silicon, are of *very* poor quality
> -- and thermal variations! Normally, this would be a "why waste the
> time, just use tubes," situation, but good output transformers are
> heavy, big, and expensive, and if the amps used in compact disk players,
> as well as TV's, could be considerably improved, that would be nice! And
> of course, inexpensive amps that sound very good are always in demand.

You do talk a shocking amount of drivel !

Graham

[Arny Krueger]

"Phil" > wrote in message


> Nevertheless, it is a given, in my mind, that a very high
> open loop gain, with its need to constantly "correct"
> every input signal by 99% (in the case of 40 dB
> feedback), *regardless* of the inherent linearity of the
> amp's devices and circuit, MUST cause problems for
> signals 60 dB to 80 dB below the main signal, and perhaps
> also phase shift the high frequency components, as
> Aczel's summary of Otala's paper states, thereby robbing
> the circuit of much of its "life" and "air," the
> criticisms one normally hears about high feedback amps,
> and also solid state amps, in which the solid state
> capacitances and high thermal variations also interfere
> with low level signals.

Could you be more presumptious or wrong, Phil?

>This will not show up as TIM or
> SID, unless the amp has been very poorly designed, and
> I'm still not sure how one would measure it.

There's really no way to measure your imagination, Phil.


> My best
> guess has been to use a 20 Hz signal and a much smaller
> (-60 to -80 dB) 10 KHz signal, filter out the 20 Hz
> signal from the output with a notch filter plus high pass
> filter, and either look directly at the 10 KHz signal for
> signs of distress, or filter it out with another notch
> filter, and see if phase shifting causes "sidebands" to
> appear and disappear when the 20 Hz signal is put in and
> out of the test.

You're looking for the unholy Grail, Phil.

People don't use notch filters that much any more. They just apply the test
signal and analyze the amp's output with a very good spectrum analyzer.


> Assuming that normal feedback causes problems

That takes a lot of ignorance or paranoia.

>-- and as
> Patrick says, with low feedback and tubes it isn't too
> bad, but SS amps have more problems and generally need
> more feedback

SS amps don't have more problems, if well-designed.

>-- it would be nice if we could figure out
> a way to tremendously reduce the need for feedback to
> "correct" every normal signal by 99% even when there is
> no device distortion, meaning allow the feedback to
> "focus" *only* on actual device and load non-linearities.

The error here is that there are any unavoidable problems with the
application of lots of feedback.


> Here is where Black's "feedforward" circuit may allow for
> a real advance in SS amps, especially if tubes, with
> their (generally) superior ability to handle a mix of
> high and low level signals without messing up the low
> level information, are used to provide the error signal.

In fact tubes have no such advantages.

> Properly applied, Black's feedforward scheme (but not the
> feedforward designs by many others!) does exactly this,
> it allows feedback to appear and affect the signal *only*
> when actual deviations caused by device or load
> non-linearities appear.

This is nuts.

> It may even be possible to
> correct the effects of a typical transistor's parallel
> capacitances -- which, being made of silicon, are of
> *very* poor quality -- and thermal variations!

Making really good power amps with silicon transistors is an old art that is
quite well perfected at this time.

> Normally,
> this would be a "why waste the time, just use tubes,"
> situation, but good output transformers are heavy, big,
> and expensive, and if the amps used in compact disk
> players, as well as TV's, could be considerably improved,
> that would be nice! And of course, inexpensive amps that
> sound very good are always in demand.

Thats why so many of them are made and sold - there's lots of demand for
them.

[Arny Krueger]

"Eeyore"
> wrote
in message
> Phil wrote:
>
>> Sander deWaal wrote:
>>> Phil > said:
>>>
>>>
>>>> Well Andre, it looks like it's you and me, since
>>>> everyone else has either pussied out on me (Phil
>>>> Asshole, Graham), dealt with other issues, although
>>>> probably honestly (Scott), or is waiting for further
>>>> developments (Patrick). I went by the UT library
>>>> today, and looked through several years of JAES, 1980
>>>> onward, but only found one article by Matti Otala. I
>>>> think maybe he published some papers in IEEE, I'll
>>>> have to check. However, in the Jan. 1980 JAES issue,
>>>> there is an article by Vanderkooy and Lip****z called
>>>> "Feedforward Error Correction in Power Amplifiers"
>>>> that looks *very* interesting! I haven't thoroughly
>>>> looked at it yet, but they review all the various
>>>> types of feedforward schemes, starting with the one
>>>> invented by Harold Black in 1923! They also review the
>>>> Quad 405, which is a different type of feedforward,
>>>> which I can state from personal experience sounds
>>>> pretty bad compared to any decent tube amp.
>>>
>>>
>>>
>>> That you didn't find much after 1980, is because mr.
>>> Otala published his findings in the early '70s.
>>>
>>> At that time, the problems as described by him, were a
>>> reality in may commercial amplifiers, and we've learned
>>> a lot since then.
>>>
>>> Later, people like Daugherty and Greiner proved that
>>> (large factors of) feedback isn't the evil that may
>>> seem to think it is, and that it doesn't necessarily
>>> generate additional distortion, when applied correctly.
>>>
>>> I happen to think that Otala has played a major role in
>>> getting more insight in what happens in an amplifier
>>> stage with feedback.
>>>
>>> Others after him corrected and modified his findings.
>>>
>>>
>>> There are more ways that lead to Rome.
>>>
>>>
>>> BTW a modified 405-II can sound very good, at least to
>>> these ears.
>>>
>> The Quad I heard was not modified, so I couldn't say,
>> although the one I heard sounded very good unless
>> compared to a good PP tube amp.
>>
>> I want to emphasize that the original subject here is
>> not what Phil Allison implies, namely TIM or SID, but
>> rather the question of whether negative feedback causes
>> audible problems even when there is no TIM. I'll go
>> ahead and quote the review of Otala's paper I gave in
>> the other thread, from "The Audio Critic," Vol 2, #2, p
>> 37, regarding Matti Otala's analysis of feedback (made
>> after he, the editor Peter Aczel, Mitch Cotter, Stew
>> Hegeman, Andy Rappaport, Max Wilcox, and Bruce Zayde had
>> a "BS" session in TAC);
>>
>> "The paper presents rigorous mathematical proof, for the
>> most generalized, all-inclusive case, that feedback
>> cannot make amplifier distortions go away; all it can do
>> is to change one kind of distortion into another. By the
>> application of feedback, the amplitude nonlinearities of
>> the open loop are converted into phase nonlinearities of
>> the closed loop. That's all. The garbage cannot, by
>> definition, be made to disappear; it's simply swept into
>> another corner. In the typical feedback amplifier, the
>> amplitude of the audio signal phase-modulates the
>> high-frequency components of the signal. Furthermore,
>> any amplitude intermodulation distortion in the open
>> loop is converted into phase intermodulation distortion
>> in the closed loop. What about TIM, alias SID? It turns
>> out that it (he?) is a limit case of this
>> feedback-generated phase modulation effect, with all
>> shades of gray possible before the actual black eruption
>> occurs. None of this shows up on standard tests."
>>
>> I still can't find this paper, despite several trips to
>> the UT library, but a little thought shows that it
>> actually is consistent with much of what you and the
>> others ae saying. When an amp with, say, 40 dB of
>> feedback is hit with a step, the output initially has an
>> "error" of 100 x, *independent* of any gain or load
>> non-linearities, which must be "corrected" by the
>> feedback loop. For every single change in the input
>> voltage, the gain is off by a factor of 95 to 105,
>> depending on gain and load non-linearities, and this
>> error must be corrected by the feedback loop.
>> Intuitively, it seems obvious that Otala's proof must in
>> *some* way be correct, that this constant "correction"
>> must play havoc with low level and high frequency
>> signals. I don't think anyone would deny that, given an
>> amp with variable feedback followed by a pot to equalize
>> the overall gain, turning up the feedback will
>> eventually make an amp that, like the Crown preamp, will
>> "bite your ears off," even if the amp never gets into
>> TIM territory or other obvious problems. The question is
>> how much of an effect does Otala's "dynamic phase
>> shifting" have. Here again, it seems obvious that part
>> of the problem was the S-L-O-W power transistors of the
>> late '70's, when Otala's various articles were written.
>> I suspect that high speed devices reduce the problems
>> created by feedback, the amount of phase distortion
>> produced, and of course Otala himself came up with
>> several ideas to reduce these effects in his Citation XX
>> design, although I also haven't been able to find any
>> literature on that design.
>>
>> Nevertheless, it is a given, in my mind, that a very
>> high open loop gain, with its need to constantly
>> "correct" every input signal by 99% (in the case of 40
>> dB feedback), *regardless* of the inherent linearity of
>> the amp's devices and circuit, MUST cause problems for
>> signals 60 dB to 80 dB below the main signal, and
>> perhaps also phase shift the high frequency components,
>> as Aczel's summary of Otala's paper states, thereby
>> robbing the circuit of much of its "life" and "air," the
>> criticisms one normally hears about high feedback amps,
>> and also solid state amps, in which the solid state
>> capacitances and high thermal variations also interfere
>> with low level signals. This will not show up as TIM or
>> SID, unless the amp has been very poorly designed, and
>> I'm still not sure how one would measure it. My best
>> guess has been to use a 20 Hz signal and a much smaller
>> (-60 to -80 dB) 10 KHz signal, filter out the 20 Hz
>> signal from the output with a notch filter plus high
>> pass filter, and either look directly at the 10 KHz
>> signal for signs of distress, or filter it out with
>> another notch filter, and see if phase shifting causes
>> "sidebands" to appear and disappear when the 20 Hz
>> signal is put in and out of the test.
>>
>> Assuming that normal feedback causes problems -- and as
>> Patrick says, with low feedback and tubes it isn't too
>> bad, but SS amps have more problems and generally need
>> more feedback -- it would be nice if we could figure out
>> a way to tremendously reduce the need for feedback to
>> "correct" every normal signal by 99% even when there is
>> no device distortion, meaning allow the feedback to
>> "focus" *only* on actual device and load
>> non-linearities. Here is where Black's "feedforward"
>> circuit may allow for a real advance in SS amps,
>> especially if tubes, with their (generally) superior
>> ability to handle a mix of high and low level signals
>> without messing up the low level information, are used
>> to provide the error signal. Properly applied, Black's
>> feedforward scheme (but not the feedforward designs by
>> many others!) does exactly this, it allows feedback to
>> appear and affect the signal *only* when actual
>> deviations caused by device or load non-linearities
>> appear. It may even be possible to correct the effects
>> of a typical transistor's parallel capacitances --
>> which, being made of silicon, are of *very* poor quality
>> -- and thermal variations! Normally, this would be a
>> "why waste the time, just use tubes," situation, but
>> good output transformers are heavy, big, and expensive,
>> and if the amps used in compact disk players, as well as
>> TV's, could be considerably improved, that would be
>> nice! And of course, inexpensive amps that sound very
>> good are always in demand.
>
> You do talk a shocking amount of drivel !

I think "Phil" is just Moncreiff or Jung posting under an alias. ;-)

[George M. Middius]

Another dose of Krooglish gets Mr. **** girded for his weekend joust with
Rev. Poop-Head at the Goose Puke Baptist church.

> Could you be more presumptious

Nobody in the history of the world has ever been "presumptious", you dumb
****. Stop lying, please.




--

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

[Arny Krueger]

"George M. Middius" <cmndr [underscore] george [at] comcast
[dot] net> wrote in message

> Another dose of Krooglish gets Mr. **** girded for his
> weekend joust with Rev. Poop-Head at the Goose Puke
> Baptist church.
>
>> Could you be more presumptious
>
> Nobody in the history of the world has ever been
> "presumptious", you dumb ****. Stop lying, please.

Note Middius' amazing ability to herniate in public himself over a typo.

[George M. Middius]

More lies from LiarBorg. I'm not surprised. Shall we notify Rev. Poop-Head
that Arnii is renewing his vows to be a good "chrisitan"? ;-)

> >> Could you be more presumptious

> > Nobody in the history of the world has ever been
> > "presumptious", you dumb ****. Stop lying, please.

> Note Middius' amazing ability to herniate[sic] in public himself over a typo.

"I apologize for being presumptious."
A. Krooger, 20 July 2000

"Since I'm not claiming to be able to read your mind, the act you consider
presumptious did not happen."
A. Krooger, 17 June 2000

"Presumptious little minx aren't you, Jenn?"
A. Krooger, 4 April 2006

"... any reasonable male would be a lot more worried about the
"Presumptious" part."
A. Krooger, 7 September 2001




--

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

[Jenn]

In article >,
George M. Middius <cmndr [underscore] george [at] comcast [dot] net>
wrote:

> More lies from LiarBorg. I'm not surprised. Shall we notify Rev. Poop-Head
> that Arnii is renewing his vows to be a good "chrisitan"? ;-)
>
> > >> Could you be more presumptious
>
> > > Nobody in the history of the world has ever been
> > > "presumptious", you dumb ****. Stop lying, please.
>
> > Note Middius' amazing ability to herniate[sic] in public himself over a
> > typo.
>
> "I apologize for being presumptious."
> A. Krooger, 20 July 2000
>
> "Since I'm not claiming to be able to read your mind, the act you consider
> presumptious did not happen."
> A. Krooger, 17 June 2000
>
> "Presumptious little minx aren't you, Jenn?"
> A. Krooger, 4 April 2006

I'd forgotten about that post LOL

>
> "... any reasonable male would be a lot more worried about the
> "Presumptious" part."
> A. Krooger, 7 September 2001
>
>
>
>
> --
>
> "Christians have to ... work to make the world as loving, just, and
> supportive as is possible."
> A. Krooger, Aug. 2006

[Phil]

Eeyore wrote:
>
> Phil wrote:
>
>
>>Sander deWaal wrote:
>>
>>>Phil > said:
>>>
>>>
>>>
>>>>Well Andre, it looks like it's you and me, since everyone else has
>>>>either pussied out on me (Phil Asshole, Graham), dealt with other
>>>>issues, although probably honestly (Scott), or is waiting for further
>>>>developments (Patrick). I went by the UT library today, and looked
>>>>through several years of JAES, 1980 onward, but only found one article
>>>>by Matti Otala. I think maybe he published some papers in IEEE, I'll
>>>>have to check. However, in the Jan. 1980 JAES issue, there is an article
>>>>by Vanderkooy and Lip****z called "Feedforward Error Correction in Power
>>>>Amplifiers" that looks *very* interesting! I haven't thoroughly looked
>>>>at it yet, but they review all the various types of feedforward schemes,
>>>>starting with the one invented by Harold Black in 1923! They also review
>>>>the Quad 405, which is a different type of feedforward, which I can
>>>>state from personal experience sounds pretty bad compared to any decent
>>>>tube amp.
>>>
>>>
>>>
>>>That you didn't find much after 1980, is because mr. Otala published
>>>his findings in the early '70s.
>>>
>>>At that time, the problems as described by him, were a reality in may
>>>commercial amplifiers, and we've learned a lot since then.
>>>
>>>Later, people like Daugherty and Greiner proved that (large factors
>>>of) feedback isn't the evil that may seem to think it is, and that it
>>>doesn't necessarily generate additional distortion, when applied
>>>correctly.
>>>
>>>I happen to think that Otala has played a major role in getting more
>>>insight in what happens in an amplifier stage with feedback.
>>>
>>>Others after him corrected and modified his findings.
>>>
>>>
>>>There are more ways that lead to Rome.
>>>
>>>
>>>BTW a modified 405-II can sound very good, at least to these ears.
>>>
>>
>>The Quad I heard was not modified, so I couldn't say, although the one I
>>heard sounded very good unless compared to a good PP tube amp.
>>
>>I want to emphasize that the original subject here is not what Phil
>>Allison implies, namely TIM or SID, but rather the question of whether
>>negative feedback causes audible problems even when there is no TIM.
>>I'll go ahead and quote the review of Otala's paper I gave in the other
>>thread, from "The Audio Critic," Vol 2, #2, p 37, regarding Matti
>>Otala's analysis of feedback (made after he, the editor Peter Aczel,
>>Mitch Cotter, Stew Hegeman, Andy Rappaport, Max Wilcox, and Bruce Zayde
>>had a "BS" session in TAC);
>>
>>"The paper presents rigorous mathematical proof, for the most
>>generalized, all-inclusive case, that feedback cannot make amplifier
>>distortions go away; all it can do is to change one kind of distortion
>>into another. By the application of feedback, the amplitude
>>nonlinearities of the open loop are converted into phase nonlinearities
>>of the closed loop. That's all. The garbage cannot, by definition, be
>>made to disappear; it's simply swept into another corner. In the typical
>>feedback amplifier, the amplitude of the audio signal phase-modulates
>>the high-frequency components of the signal. Furthermore, any amplitude
>>intermodulation distortion in the open loop is converted into phase
>>intermodulation distortion in the closed loop. What about TIM, alias
>>SID? It turns out that it (he?) is a limit case of this
>>feedback-generated phase modulation effect, with all shades of gray
>>possible before the actual black eruption occurs. None of this shows up
>>on standard tests."
>>
>>I still can't find this paper, despite several trips to the UT library,
>>but a little thought shows that it actually is consistent with much of
>>what you and the others ae saying. When an amp with, say, 40 dB of
>>feedback is hit with a step, the output initially has an "error" of 100
>>x, *independent* of any gain or load non-linearities, which must be
>>"corrected" by the feedback loop. For every single change in the input
>>voltage, the gain is off by a factor of 95 to 105, depending on gain and
>>load non-linearities, and this error must be corrected by the feedback
>>loop. Intuitively, it seems obvious that Otala's proof must in *some*
>>way be correct, that this constant "correction" must play havoc with low
>>level and high frequency signals. I don't think anyone would deny that,
>>given an amp with variable feedback followed by a pot to equalize the
>>overall gain, turning up the feedback will eventually make an amp that,
>>like the Crown preamp, will "bite your ears off," even if the amp never
>>gets into TIM territory or other obvious problems. The question is how
>>much of an effect does Otala's "dynamic phase shifting" have. Here
>>again, it seems obvious that part of the problem was the S-L-O-W power
>>transistors of the late '70's, when Otala's various articles were
>>written. I suspect that high speed devices reduce the problems created
>>by feedback, the amount of phase distortion produced, and of course
>>Otala himself came up with several ideas to reduce these effects in his
>>Citation XX design, although I also haven't been able to find any
>>literature on that design.
>>
>>Nevertheless, it is a given, in my mind, that a very high open loop
>>gain, with its need to constantly "correct" every input signal by 99%
>>(in the case of 40 dB feedback), *regardless* of the inherent linearity
>>of the amp's devices and circuit, MUST cause problems for signals 60 dB
>>to 80 dB below the main signal, and perhaps also phase shift the high
>>frequency components, as Aczel's summary of Otala's paper states,
>>thereby robbing the circuit of much of its "life" and "air," the
>>criticisms one normally hears about high feedback amps, and also solid
>>state amps, in which the solid state capacitances and high thermal
>>variations also interfere with low level signals. This will not show up
>>as TIM or SID, unless the amp has been very poorly designed, and I'm
>>still not sure how one would measure it. My best guess has been to use a
>>20 Hz signal and a much smaller (-60 to -80 dB) 10 KHz signal, filter
>>out the 20 Hz signal from the output with a notch filter plus high pass
>>filter, and either look directly at the 10 KHz signal for signs of
>>distress, or filter it out with another notch filter, and see if phase
>>shifting causes "sidebands" to appear and disappear when the 20 Hz
>>signal is put in and out of the test.
>>
>>Assuming that normal feedback causes problems -- and as Patrick says,
>>with low feedback and tubes it isn't too bad, but SS amps have more
>>problems and generally need more feedback -- it would be nice if we
>>could figure out a way to tremendously reduce the need for feedback to
>>"correct" every normal signal by 99% even when there is no device
>>distortion, meaning allow the feedback to "focus" *only* on actual
>>device and load non-linearities. Here is where Black's "feedforward"
>>circuit may allow for a real advance in SS amps, especially if tubes,
>>with their (generally) superior ability to handle a mix of high and low
>>level signals without messing up the low level information, are used to
>>provide the error signal. Properly applied, Black's feedforward scheme
>>(but not the feedforward designs by many others!) does exactly this, it
>>allows feedback to appear and affect the signal *only* when actual
>>deviations caused by device or load non-linearities appear. It may even
>>be possible to correct the effects of a typical transistor's parallel
>>capacitances -- which, being made of silicon, are of *very* poor quality
>>-- and thermal variations! Normally, this would be a "why waste the
>>time, just use tubes," situation, but good output transformers are
>>heavy, big, and expensive, and if the amps used in compact disk players,
>>as well as TV's, could be considerably improved, that would be nice! And
>>of course, inexpensive amps that sound very good are always in demand.
>
>
> You do talk a shocking amount of drivel !
>
> Graham
>
Here's a suggestion, Useless: Why don't you share with us some of YOUR
insights and analyses so we could what "non-drivel" looks like. Unless,
of course, a useless pussy like yourself (or Arny) has none, or is too
much of a coward to stick your neck out. The only useless drivel I see
is the CONSTANT use by you and Arny of that same old, OLD, tired,
debating trick of putting out a general criticism, with no specific
examples, and no supporting evidence. And no matter how many times it
gets pointed out to you, we can all count on one thing; your next post
will do it again. I've seen useless pussies before, but until you two
came along, I had not seen petrified useless pussies. You two are
unique, that I'll admit.

Phil

[Phil]

Patrick Turner wrote:

[snip]
>>Well, remember, the maximum slew rate found in audio signals is much
>>greater than what a theoretical 20 KHz signal is going to supply, and
>>not all power amps, with their big, slow, output transistors, are going
>>to be as fast as even a 741.
>
>
> Not all output bjts are big and slow.
> Some do however dislike turning OFF quickly and some display the truly
> horrible habit of cross conduction at HF, ie, the two bjts in a typical complementary
> pair
> are BOTH turned on during a wave cycle during large signal excursions at above 10kHz,
> and the power supply has to supply a lot more current that is simply passing from rail
> to rail
> and its hang onto your hat time for the ride.
>
>
>>Plus, the point of Matti's work is that
>>problems begin to appear at all levels below the theoretical
>>"breakthrough" point of TIM/SID. In any case, the topic here is not
>>whether most amps have sufficient slew rate -- I assume that *most* good
>>amps do -- but rather about Otala's proof that a feedback amp's
>>"correction" of an amplitude distortion of the open loop phase shifts
>>the high frequency components in the closed loop.
>
>
> Both amplitude distortions and phase distortions of the open loop
> response are BOTH corrected by the NFB.
> Typical open loop phase lag in open loop at 20kHz is 90 degrees, and the 40dB of
> applied global NFB
> at 20kHz reduces this typically to less than 5 degrees.

Patrick, for god's sake, if you disagree with me, fine, but how many
times do I have to say that what Matti was talking about was not the
usual lag at 20 KHz, but rather phase-SHIFTING, as in MOVEMENT, not lead
or lag, that as you yourself correctly guessed, is a function of low
frequency amplitude, not overall frequency. Yes, feedback allows greater
bandwidth, thereby improving "phase distortion," where distortion is
defined as CONSTANT phase shift as a function of frequency. Otala, the
technical director of the Finnish Institute for whatever, was not that
stupid! Come on, you know that "dynamic phase distortion" refers to
something else, you said so yourself.
>
>
>>I am currently
>>discussing this in the "Negative Feedback in Triodes: The Logical and
>>Experimental Proof" thread from 8/15, so if you're interested, look
>>there (articles posted on 9/6). Phil Allison had a "response" here --
>>his usual slams and blams with no supporting evidence -- but I actually
>>would like to see his simple test that can show whether low frequency
>>signals in a feedback amp do or do not cause high frequency phase
>>shifting, as it would be useful test, and I'm having a hard time coming
>>up with a simple way to test that myself.
>
>
> Just apply 70Hz and 5kHz signals to the input of an amp
> in a 4:1 ratio.
> Filter out all below 1kHz from the output signal.
> Then you will see what the effect of the 70Hz large signal is upon the
> fidelity of the 5kHz signal and whether there is any phase modulation
> in addition to the expected intermodulation.
> With most well made SS high NFB amps, the IMD is not visible on the CRO
> and a careful peak detector must be used to measure amplitude variations in the 5kHz,
> or else filter out the IMD products at 4,930Hz and 5,070Hz.

Thank you, but there may be more to it than that. For one, let's see
what happens when the 70Hz signal is 80 dB higher than the 5KHz signal,
and let's make certain that our equipment is sensitive to rapid forward
and backward shifts in time of the 5KHz signal. A 'scope would almost
certainly catch that IF triggered with a constant timer, not the 5KHz
signal.
>
>
>
>
>
>>Apparently, Otala incorporated
>>a lot of ideas/solutions into his Citation XX power amp, and maybe, if I
>>can find papers by him on that amp, there will be some useful
>>information and tests there, but if PA can come up with something in the
>>meantime, hell that's fine by me! He'll probably think of something
>>really simple and easy, and then refuse to tell me, the ****head ...
>
>
> But all these investigations have been done many times before.

Could you name one?
>
> What exactly do you hope to gain by goading the ungoadables on the group
> to find out what you should be willing to find out for yourself?

Who said I was trying to "hire for free" the ungoadables? I am
discussing a subject, including possible problems and solutions.
Ideally, we all have a complete workbench, but I think it's a bit
bigoted to imply to those of us who do not that we should get our own
bench and do all investigations ourselves, before we are permitted to
discuss a subject here.
>
> Do you suspect to find some hitherto unused uninvented techniques of making
> amplifiers perform better?

I can almost say, "Duh, of course!" However, I do not necessarily EXPECT
to do anything, because I AM discussing a subject, which I have a
right to do on this list, as it is basically what the list is all about!
Besides, you have yet to give an honest answer to a method I suggested
that should improve things, my higher resolution double-blind
suggestion. I gave you a PROOF -- which is no more and no less reliable
than the premises -- that if you use that method, you can find
differences between components that the normal double blind cannot
reveal. That will not automatically enable you to make a better amp and
make more money, but it should help! You're welcome, by the way ...
>
>
>>
>>Anyway, what PA was saying/yelling is that feedback amps DO NOT EITHER
>>CAUSE PHASE SHIFTING OF THE HIGH FREQUENCIES LIKE THAT DUMMY DR. OTALA
>>SAID! My response was simply to ask whether (1) he knew of references
>>that would back up his claim, that Otala's analysis was flawed, and (2)
>>whether he knew of a good, simple test that can be used to test whether
>>LF signals in a feedback amp cause phase shifting of the HF signals,
>>like Otala said they do.
>
>
> Be like me, find out by building one's own test gear and testing.
> It took me months to do it all but after reading all the conflicting opinions about
> all this in
> Electronics World copies from the 1970s to 1980s BEFORE the internet was mainstream,
> I decided to look myself at what happened in amps that i should be worried about.

And I am impressed by that. You are not, like Graham or Arny, either
useless or a pussy. But not everyone can do that, and it is unfair of
you to suggest otherwise.

Phil
>
> Patrick Turner.
>
>
>>
>>Phil
>>
>>To email me directly, cut off my head
>>
>>>
>

[Phil]

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

[Eeyore]

"George M. Middius" wrote:

> Another dose of Krooglish gets Mr. **** girded for his weekend joust with
> Rev. Poop-Head at the Goose Puke Baptist church.
>
> > Could you be more presumptious
>
> Nobody in the history of the world has ever been "presumptious", you dumb
> ****. Stop lying, please.

Ejsy fof upi dsu ?

Graham

[Eeyore]

"George M. Middius" wrote:

> More lies from LiarBorg. I'm not surprised. Shall we notify Rev. Poop-Head
> that Arnii is renewing his vows to be a good "chrisitan"? ;-)
>
> > >> Could you be more presumptious
>
> > > Nobody in the history of the world has ever been
> > > "presumptious", you dumb ****. Stop lying, please.
>
> > Note Middius' amazing ability to herniate[sic] in public himself over a typo.
>
> "I apologize for being presumptious."
> A. Krooger, 20 July 2000
>
> "Since I'm not claiming to be able to read your mind, the act you consider
> presumptious did not happen."
> A. Krooger, 17 June 2000
>
> "Presumptious little minx aren't you, Jenn?"
> A. Krooger, 4 April 2006
>
> "... any reasonable male would be a lot more worried about the
> "Presumptious" part."
> A. Krooger, 7 September 2001

How's that new sub-editor position going btw Georgie Porgy puddikins ?

Graham

[Eeyore]

Phil wrote:

> Eeyore wrote:
> > Phil wrote:
> It may even
> >>be possible to correct the effects of a typical transistor's parallel
> >>capacitances -- which, being made of silicon, are of *very* poor quality
> >>-- and thermal variations!

Bwahahahahahhaha !

> Normally, this would be a "why waste the
> >>time, just use tubes," situation, but good output transformers are
> >>heavy, big, and expensive, and if the amps used in compact disk players,
> >>as well as TV's, could be considerably improved, that would be nice! And
> >>of course, inexpensive amps that sound very good are always in demand.
> >
> >
> > You do talk a shocking amount of drivel !
> >
> > Graham
> >
> Here's a suggestion, Useless: Why don't you share with us some of YOUR
> insights and analyses so we could what "non-drivel" looks like.

Well........ since it would be based on sound engineering science, I suspect it
might have limited appeal.


> Unless,
> of course, a useless pussy like yourself (or Arny) has none, or is too
> much of a coward to stick your neck out. The only useless drivel I see
> is the CONSTANT use by you and Arny of that same old, OLD, tired,
> debating trick of putting out a general criticism, with no specific
> examples, and no supporting evidence. And no matter how many times it
> gets pointed out to you, we can all count on one thing; your next post
> will do it again. I've seen useless pussies before, but until you two
> came along, I had not seen petrified useless pussies. You two are
> unique, that I'll admit.

If you knew anything about electronic design and solid-state physics you
wouldn't make such stupid comments about parallel capacitance in transistors for
example.

Tell me more about this and how it works and them I'll correct you OK ?

Graham

[Eeyore]

Phil wrote:

> Patrick Turner wrote:
>
> > Just apply 70Hz and 5kHz signals to the input of an amp
> > in a 4:1 ratio.
> > Filter out all below 1kHz from the output signal.
> > Then you will see what the effect of the 70Hz large signal is upon the
> > fidelity of the 5kHz signal and whether there is any phase modulation
> > in addition to the expected intermodulation.
> > With most well made SS high NFB amps, the IMD is not visible on the CRO
> > and a careful peak detector must be used to measure amplitude variations in the 5kHz,
> > or else filter out the IMD products at 4,930Hz and 5,070Hz.
>
> Thank you, but there may be more to it than that. For one, let's see
> what happens when the 70Hz signal is 80 dB higher than the 5KHz signal,
> and let's make certain that our equipment is sensitive to rapid forward
> and backward shifts in time of the 5KHz signal.

Bwahahahahahahhah !

> A 'scope would almost
> certainly catch that IF triggered with a constant timer, not the 5KHz
> signal.

Do you have a degree in stupidity or simply just denseness ?

Graham

[Eeyore]

Phil wrote:

> 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 ...

If the concept was even right in the first place then logically it would indeed
'cancel' out.

Graham

[Phil Allison]

"Eeyore"
>
>> 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 ...
>
> If the concept was even right in the first place then logically it would
> indeed
> 'cancel' out.


** Nonsense.

Shifting the origin point of a steady wave changes its phase at the position
of a test mic - as would shifting the mic.

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.

Dymamic mic diaphragms make only tiny excursions ( condenser mics even
less ) compared to loudspeaker cones - so they react to the pressure at a
fixed point.




........ Phil Allison

[Chris Hornbeck]

On Fri, 08 Sep 2006 19:21:10 GMT, Phil >
wrote:

>I'll go ahead and quote the review of Otala's paper I gave in the other
>thread, from "The Audio Critic," Vol 2, #2, p 37, regarding Matti
>Otala's analysis of feedback (made after he, the editor Peter Aczel,
>Mitch Cotter, Stew Hegeman, Andy Rappaport, Max Wilcox, and Bruce Zayde
>had a "BS" session in TAC);

You really want to read Otala's own work. It's an important
historical piece, and has *nothing* to do with the stuff
quoted.

All good fortune,

Chris Hornbeck
"Man is the measure of all things. Sigh.
Happy Ears!" -Al

[Chris Hornbeck]

On Fri, 08 Sep 2006 23:59:14 GMT, Phil >
wrote:

>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.

No.

> 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?

Or a conventional IM distortion analyzer.

> 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?

If they were perfectly coupled, yes. But symmetry is broken.

All good fortune,

Chris Hornbeck
"Man is the measure of all things. Sigh.
Happy Ears!" -Al

[Ian Iveson]

Phil said:

>> 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.

Army may not be interested in reinventing the wheel, but I quite like
the idea of applying transistor-era thinking back to valve designs. So
thanks for the provocation.

As regards Doppler. I look at Wikipedia and see that the relative
velocity is assumed (by Wikipedia at least) to be constant. The
frequency shift is therefore also constant and so clearly defined. A
changing shift in frequency is an awkward concept, especially if it
changes sinusoidally.

Phase and frequency are two sides of the same kettle of geese. A
constant shift in phase is a change in frequency. Whether one is
changing or the other depends on how you look at it. Possibly, in our
case, how we actually hear it.

Now, apparently some useful information can be gleaned from observing
how the velocities of binary stars, with respect to us, vary as they
orbit each other. The changing velocities are calculated from changing
colours, assuming that the Doppler effect is the sole cause of the
change. That is an example very close to your speaker idea, where a
source moving at a relatively low frequency modulates the higher
frequency of an emitted signal.

But. In the case of the binary star, the difference between the two
frequencies is huge. So great that, for the time it takes to detect a
shift in the higher frequency, the source can be assumed to be moving
at constant velocity.

How far must the frequencies be apart in order to result in something
that can be properly called the Doppler effect? Well, Wikipedia says
frequency shift, so at what point, as you move the frequencies closer,
does it stop resulting in a frequency shift?

Let's take the obvious example of making the two frequencies the same.
Does it make sense to say that the resulting tone, being exactly the
same but with an amplitude shift of anywhere between 1 and -1, is a
consequence of the Doppler effect? Is a shift in amplitude the same
thing as a shift in frequency?

The audio band isn't many orders of magnitude wide. It is probably
more convenient to characterise the effect you speak of in terms of
phase, rather than frequency. Then it stops being a proper Doppler
effect, perhaps.

Your oscillating train example has much greater difference between the
source and signal frequencies. Perhaps you know that already.

Real-time spectrum analysis is another tricky concept.

Ultimately, it's how your ear appreciates it that counts, of course,
etc.

cheers, Ian

[Ian Iveson]

I wrote

> A constant shift in phase is a change in frequency.

er...constantly shifting...I know what I mean...

[Robert Morein]

"George M. Middius" wrote:
> Another dose of Krooglish gets Mr. **** girded for his weekend joust with
> Rev. Poop-Head at the Goose Puke Baptist church.
>
>> Could you be more presumptious
>
> Nobody in the history of the world has ever been "presumptious", you dumb
> ****. Stop lying, please.
>

"I'd like to have as many men and women as possible **** me in the ass
before I die"
George Middius, 8th Grade Graduation Ceremony

[Phil]

Eeyore wrote:
>
> Phil wrote:
>
>
>>Eeyore wrote:
>>
>>>Phil wrote:
>>
>>It may even
>>
>>>>be possible to correct the effects of a typical transistor's parallel
>>>>capacitances -- which, being made of silicon, are of *very* poor quality
>>>>-- and thermal variations!
>
>
> Bwahahahahahhaha !
>
>
>>Normally, this would be a "why waste the
>>
>>>>time, just use tubes," situation, but good output transformers are
>>>>heavy, big, and expensive, and if the amps used in compact disk players,
>>>>as well as TV's, could be considerably improved, that would be nice! And
>>>>of course, inexpensive amps that sound very good are always in demand.
>>>
>>>
>>>You do talk a shocking amount of drivel !
>>>
>>>Graham
>>>
>>
>>Here's a suggestion, Useless: Why don't you share with us some of YOUR
>>insights and analyses so we could what "non-drivel" looks like.
>
>
> Well........ since it would be based on sound engineering science, I suspect it
> might have limited appeal.
>
>
>
>>Unless,
>>of course, a useless pussy like yourself (or Arny) has none, or is too
>>much of a coward to stick your neck out. The only useless drivel I see
>>is the CONSTANT use by you and Arny of that same old, OLD, tired,
>>debating trick of putting out a general criticism, with no specific
>>examples, and no supporting evidence. And no matter how many times it
>>gets pointed out to you, we can all count on one thing; your next post
>>will do it again. I've seen useless pussies before, but until you two
>>came along, I had not seen petrified useless pussies. You two are
>>unique, that I'll admit.
>
>
> If you knew anything about electronic design and solid-state physics you
> wouldn't make such stupid comments about parallel capacitance in transistors for
> example.
>
> Tell me more about this and how it works and them I'll correct you OK ?
>
> Graham
>
Sure. You know the gate to source, gate to drain, and the drain to
source capacitances? In a solid state transistor, they are made out of a
dielectric called "silicon" -- not coincidentally, the same thing the
FETS are made of -- and it has a dielectric constant of 12, quite high.
Good, low dielectric constant materials, with constants of 2 to 3, have
enough dielectric absorption to require precision instruments to use
several parallel RC units to offset the noise dumped by the main
capacitors (see p 220 of Horowitz and Hill, "The Art of Electronics").
High dielectric materials are much worse (note the usual warnings for
electrolytic caps, with a mere dielectric constant of 7 to 8), and
NOBODY in their right mind would even dream of using a silicon capacitor
in any circuit required to pass signals in which many important signals
are 80 dB or more below the main signals; you know, like you find in music?

Take just the Cds cap: as the signal moves up and down, the dielectric
absorption of this cap stores and releases energy all the time,
polluting the signal. This pollution is at a very low level, and if
music only used about 40 dB or so, it *might* not be noticeable, or at
least, just barely noticeable. But with music the range is closer to 100
dB, even with analog (humans can easily hear 40 dB into noise, something
the old telegraph operators normally achieved). In contrast, a vacuum
tube has capacitances made out of, well, a vacuum, the medium of space,
which has, as far as we know, no dielectric absorption at all. In
addition -- as you, of course, already know, as can be proven in some of
your old posts here -- the transistor's capacitances *vary* as a
function of both voltage and heat, and the heat varies as a function of
the device's recent signal history, meaning it does *not* follow the
musical signal in a harmonic way, but rather as an rms average over the
most recent second or so. When a capacitance increases or decreases, and
the voltage remains the same, guess what? That's right, the charge
increases or decreases, meaning it gets sucked from or dumped into the
signal in a non-harmonic way. Now, if we have a device with vacuum
capacitors to compare the input versus the silicon capacitor gunked-up
output, we might, just might, be able to offset the crap dumped into the
signal by those capacitors. Clear enough?

Now, you can go into debate mode, in which truth, honesty, and
intelligence are meaningless, and the only goal is to attack your
"opponent's" statements, or you can be honest here. Gee, what do I think
a useless pussy like you will do? Golly, that's a hard one ... Let's
see, "Well, see, modern transistors are free of this." Excuse me, have
you LOOKED at the cap data for MOSFETS (or even power bipolars) lately?
For very small signals, using very small transistors, you can reduce
this effect to -60 dB or so, with great care maybe even -80 dB, or with
tremendous care and many offsetting components, maybe 120 dB, which I
suspect would then be inaudible. But I do not know of a preamp design
which achieves anywhere near 120 dB, although I obviously have not seen
all the circuits out there. Wake up, useless; I will unhappily admit
that I am all too frequently wrong, but I am NOT stupid, and only a
useless, sanctimonious snot like yourself would even try to convince
himself otherwise. But maybe I'm just kidding myself, because maybe you
can list some of your old posts here that not only discuss the subject
of the effect that the solid state parasitic capacitances have on audio
circuits, but which are free of the "many errors" that you will claim
exist, but as always, without actually giving even one example of these
errors. Oh, and no word -- of course -- concerning how many of my points
are correct; that would violate debate rules, which are the only rules
that anyone should ever use! You know, I have terminal cancer, and maybe
heart problems (waiting for the results), but I would rather be me, and
dead soon, than an utterly useless pussy like you, for decades. And no,
my physical problems should NEVER excuse me from INTELLIGENT criticism.

Disgusted Phil

[Phil Allison]

"Phil"

>
> 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.





........ Phil

[Tom A.]

I only know Matti Otala from being the designer of a particular set of
top of the range Harman Kardon pre/power amp, that got great reviews in
the 80s. I might be mistaken, but isn't he the designer of several well
regarded Electrocompaniet amps?

Here is a link to pictures of the HK set: http://www.popolo.com/citation.html

Tom



> Well Andre, it looks like it's you and me, since everyone else has
> either pussied out on me (Phil Asshole, Graham), dealt with other
> issues, although probably honestly (Scott), or is waiting for further
> developments (Patrick). I went by the UT library today, and looked
> through several years of JAES, 1980 onward, but only found one article
> by Matti Otala. I think maybe he published some papers in IEEE, I'll
> have to check. However, in the Jan. 1980 JAES issue, there is an
> article by Vanderkooy and Lip****z called "Feedforward Error Correction
> in Power Amplifiers" that looks *very* interesting! I haven't
> thoroughly looked at it yet, but they review all the various types of
> feedforward schemes, starting with the one invented by Harold Black in
> 1923! They also review the Quad 405, which is a different type of
> feedforward, which I can state from personal experience sounds pretty
> bad compared to any decent tube amp.
>
> My interest in this is due to my initial conclusion from Otala's paper,
> namely that a method of feedback -- which we have to have if using
> solid state devices to obtain low output impedance-- that is quite
> different from the usual feedback scheme, would avoid the dynamic phase
> shifting problem. I had worked out an obvious overall topology, which
> turned out to be almost exactly the same as Black's feedforward scheme
> of 1923! Whoa ... Briefly, the problem as I see it, is that when a
> standard feedback amp with, say, 40 dB of feedback is initially hit
> with a step signal, the initial output is 100 times too large as seen
> by the feedback circuit. Note that even if the gain is constant, and
> the load is a perfect resistor of just the right size to give exactly
> 100 x open loop, the feedback loop sees an ERROR of 99%. This, I
> suspect, is what kills high feedback amplifiers. It would be one thing
> if only the minor errors due to slight gain variations in the
> transistors and impedance variations in the load were converted in to
> phase distortion, but as far as I can see, the feedback error loop
> cannot possibly distinguish between those minor errors, and the 100 x
> gain error that is inherent to the loop! In other words, the excess
> gain that is used to obtain 40 dB of feedback is itself seen as an
> error, and converted into phase distortion, just like the "real" errors
> in the load and output devices. Of course, this error only exists when
> a signal is present, but every perfect sine wave signal must be 99%
> corrected, and since this "correction" is actually a *conversion* into
> phase distortion, we wind up with the horrid sound that high feedback
> SS amps so often have.
>
> The alternative, which is basically Black's original feedforward amp
> design, is to have one amp that is basically just a transconductance
> amp, x amps out per y volts in, and the output voltage from this amp is
> then compared to the input to produce an error signal. This signal is
> then sent to a second, parallel amp, whose output is then added to the
> first amp's output. Ideally, you have two time delay circuits to offset
> the delay through the two amps, and it might be possible to use a
> parallel resistor in the output to supply some of the damping, but
> these are mostly details. The main point is that almost all of the
> "correction" signal would in fact be due to load variations (the second
> amp's gain is adjusted to match the first amp's gain), and *not* from
> the excess gain of the feedback amp, thereby greatly reducing the
> amount of dynamic phase distortion. Furthermore, since this feedback
> signal can "concentrate on the true errors" (whereas a normal feedback
> amp "concentrates" 98% to 99% on the excess gain, and only 1% to 2% on
> the true errors), it may be much more effective at counteracting the
> errors from the inherent crappy SS capacitors that come with any SS
> device, and also the SS thermal variations, which are much greater than
> the thermal variations of tubes. These capacitance and thermal defects
> are, I suspect, the other reason (in addition to feedback phase
> distortion) why power SS amps seem to be worse at amplifying a mixture
> of high and low amplitude signals -- i.e., music -- than tubes. These
> errors "mess up" the low level signals, causing SS amps to have less
> life and air than tube amps. Finally, the "error amp" in Black's
> feedforward design, which sends a signal to the second parallel amp,
> can be a vacuum tube, and since this *is* able to amplify high and low
> signals, it can more easily correct the destruction of the low level
> signals by the main amps! In other words, we can use a vacuum tube to
> insure quality amplification of the entire music signal, high and low
> level, and use this to correct the inability of power SS amps to do the
> same. In a normal feedback amp this would be largely impossible, since
> the typical level of 26 dB of feedback constantly "corrects" 95% of the
> output, converting this "error" (which is just the normal open loop
> gain) into phase distortion, something which normally would overwhelm
> the ability of a tube to restore low level information.
>
> Of course, I don't know if this will actually work, but in theory, it
> sounds VERY promising! Now, if we can just convince a few people to try
> my improved double-blind test (which mimics the actions of the Boulder
> amp people, only at rather higher speed) to select those components
> that really are capable of greater resolution, and then "dumb-down" the
> results until it is musical, we may have a truly musical, relatively
> inexpensive, almost all SS amp! If we could just get some low output
> impedance (2 ohms) power JFETS to go with it ...
>
> Phil
>
> 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

[Phil]

Phil Allison wrote:
> "Phil"
>
>
>>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.
>
>
>
>
>
> ....... Phil
>
>
>
Now THIS is cute!

Impressed Phil

[Phil]

Chris Hornbeck wrote:

> On Fri, 08 Sep 2006 19:21:10 GMT, Phil >
> wrote:
>
>
>>I'll go ahead and quote the review of Otala's paper I gave in the other
>>thread, from "The Audio Critic," Vol 2, #2, p 37, regarding Matti
>>Otala's analysis of feedback (made after he, the editor Peter Aczel,
>>Mitch Cotter, Stew Hegeman, Andy Rappaport, Max Wilcox, and Bruce Zayde
>>had a "BS" session in TAC);
>
>
> You really want to read Otala's own work. It's an important
> historical piece, and has *nothing* to do with the stuff
> quoted.
>
> All good fortune,
>
> Chris Hornbeck
> "Man is the measure of all things. Sigh.
> Happy Ears!" -Al

I would love to, but I REALLY want to read the paper he wrote, or at
least presented, referred to here, and not just his previous papers.
I've looked in JAES, and there's nothing (although I think the older
papers are there). Any ideas on how to find something like a collection
of his papers?

Thanks, Phil

[Phil]

Tom A. wrote:

> I only know Matti Otala from being the designer of a particular set of
> top of the range Harman Kardon pre/power amp, that got great reviews in
> the 80s. I might be mistaken, but isn't he the designer of several well
> regarded Electrocompaniet amps?
>
> Here is a link to pictures of the HK set:
> http://www.popolo.com/citation.html
>
> Tom
>
That is indeed the Citation XX, the one he designed after he did the
analysis on feedback. Supposed to sound fantastic, if you can find one.

Phil
>
>
>> Well Andre, it looks like it's you and me, since everyone else has
>> either pussied out on me (Phil Asshole, Graham), dealt with other
>> issues, although probably honestly (Scott), or is waiting for further
>> developments (Patrick). I went by the UT library today, and looked
>> through several years of JAES, 1980 onward, but only found one article
>> by Matti Otala. I think maybe he published some papers in IEEE, I'll
>> have to check. However, in the Jan. 1980 JAES issue, there is an
>> article by Vanderkooy and Lip****z called "Feedforward Error
>> Correction in Power Amplifiers" that looks *very* interesting! I
>> haven't thoroughly looked at it yet, but they review all the various
>> types of feedforward schemes, starting with the one invented by Harold
>> Black in 1923! They also review the Quad 405, which is a different
>> type of feedforward, which I can state from personal experience sounds
>> pretty bad compared to any decent tube amp.
>>
>> My interest in this is due to my initial conclusion from Otala's
>> paper, namely that a method of feedback -- which we have to have if
>> using solid state devices to obtain low output impedance-- that is
>> quite different from the usual feedback scheme, would avoid the
>> dynamic phase shifting problem. I had worked out an obvious overall
>> topology, which turned out to be almost exactly the same as Black's
>> feedforward scheme of 1923! Whoa ... Briefly, the problem as I see it,
>> is that when a standard feedback amp with, say, 40 dB of feedback is
>> initially hit with a step signal, the initial output is 100 times too
>> large as seen by the feedback circuit. Note that even if the gain is
>> constant, and the load is a perfect resistor of just the right size to
>> give exactly 100 x open loop, the feedback loop sees an ERROR of 99%.
>> This, I suspect, is what kills high feedback amplifiers. It would be
>> one thing if only the minor errors due to slight gain variations in
>> the transistors and impedance variations in the load were converted in
>> to phase distortion, but as far as I can see, the feedback error loop
>> cannot possibly distinguish between those minor errors, and the 100 x
>> gain error that is inherent to the loop! In other words, the excess
>> gain that is used to obtain 40 dB of feedback is itself seen as an
>> error, and converted into phase distortion, just like the "real"
>> errors in the load and output devices. Of course, this error only
>> exists when a signal is present, but every perfect sine wave signal
>> must be 99% corrected, and since this "correction" is actually a
>> *conversion* into phase distortion, we wind up with the horrid sound
>> that high feedback SS amps so often have.
>>
>> The alternative, which is basically Black's original feedforward amp
>> design, is to have one amp that is basically just a transconductance
>> amp, x amps out per y volts in, and the output voltage from this amp
>> is then compared to the input to produce an error signal. This signal
>> is then sent to a second, parallel amp, whose output is then added to
>> the first amp's output. Ideally, you have two time delay circuits to
>> offset the delay through the two amps, and it might be possible to use
>> a parallel resistor in the output to supply some of the damping, but
>> these are mostly details. The main point is that almost all of the
>> "correction" signal would in fact be due to load variations (the
>> second amp's gain is adjusted to match the first amp's gain), and
>> *not* from the excess gain of the feedback amp, thereby greatly
>> reducing the amount of dynamic phase distortion. Furthermore, since
>> this feedback signal can "concentrate on the true errors" (whereas a
>> normal feedback amp "concentrates" 98% to 99% on the excess gain, and
>> only 1% to 2% on the true errors), it may be much more effective at
>> counteracting the errors from the inherent crappy SS capacitors that
>> come with any SS device, and also the SS thermal variations, which are
>> much greater than the thermal variations of tubes. These capacitance
>> and thermal defects are, I suspect, the other reason (in addition to
>> feedback phase distortion) why power SS amps seem to be worse at
>> amplifying a mixture of high and low amplitude signals -- i.e., music
>> -- than tubes. These errors "mess up" the low level signals, causing
>> SS amps to have less life and air than tube amps. Finally, the "error
>> amp" in Black's feedforward design, which sends a signal to the second
>> parallel amp, can be a vacuum tube, and since this *is* able to
>> amplify high and low signals, it can more easily correct the
>> destruction of the low level signals by the main amps! In other words,
>> we can use a vacuum tube to insure quality amplification of the entire
>> music signal, high and low level, and use this to correct the
>> inability of power SS amps to do the same. In a normal feedback amp
>> this would be largely impossible, since the typical level of 26 dB of
>> feedback constantly "corrects" 95% of the output, converting this
>> "error" (which is just the normal open loop gain) into phase
>> distortion, something which normally would overwhelm the ability of a
>> tube to restore low level information.
>>
>> Of course, I don't know if this will actually work, but in theory, it
>> sounds VERY promising! Now, if we can just convince a few people to
>> try my improved double-blind test (which mimics the actions of the
>> Boulder amp people, only at rather higher speed) to select those
>> components that really are capable of greater resolution, and then
>> "dumb-down" the results until it is musical, we may have a truly
>> musical, relatively inexpensive, almost all SS amp! If we could just
>> get some low output impedance (2 ohms) power JFETS to go with it ...
>>
>> Phil
>>
>> 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
>
>
>

[Eeyore]

"Tom A." wrote:

> I only know Matti Otala from being the designer of a particular set of
> top of the range Harman Kardon pre/power amp, that got great reviews in
> the 80s. I might be mistaken, but isn't he the designer of several well
> regarded Electrocompaniet amps?

I've had to repair one those Electrocompianets several times. It may have been a
good design but the implementation was shockingly bad. It hummed a lot too.

Graham

[Phil]

Patrick Turner wrote:

>
> Phil wrote:
>
>
>>Eeyore wrote:
>>
>>>Phil wrote:
>>>
>>>
>>>
>>>>Eeyore wrote:
>>>>
>>>>
>>>>>For any sinewave ( see Fourier theory for applicability ) the max slew rate ( at
>>>>>zero crossing btw ) is 2.pi.f.Vpeak.
>>>>>
>>>>>For a 20kHz signal of say 2V peak amplitude that means a slew rate of 0.25 V/us
>>>>>! Even a rubbish 741 or 1458 can manage that !
>>>>>
>>>>>Given that modern audio op-amps are capable of slew rates of ~ 10V/us - you're
>>>>>never even remotely close to slew limited anything.
>>>>>
>>>>>Graham
>>>>
>>>>Well, remember, the maximum slew rate found in audio signals is much
>>>>greater than what a theoretical 20 KHz signal is going to supply,
>>>
>>>
>>>Utter drivel.
>>>
>>>Learn some science before posting such ********.
>>>
>>>bye bye.
>>>
>>>Graham
>>>
>>
>>I'll tell you what, why don't you take one point that you can attack,
>>ignore everything else, and then put out yet another unsupported
>>criticism. In audio, where you have a huge mixture of signals, the
>>waveforms periodically add together, momentarily increasing the slew
>>rate over what a typical -- read, very small amplitude -- audio 20 KHz
>>signal would have. Do you disagree with that? Would you like to state
>>here, for the public record, that you think that when several signals
>>are mixed, that there are no momentary peaks in slew rate which exceed
>>the maximum slew rate found in individual signals? By all means, show
>>everyone here how well you think, and reason, and how much you actually
>>understand about audio. Oh, BY THE WAY, do you have anything intelligent
>>and useful to say about the rest of my comments? Useless cheap shots do
>>not qualify ...
>>
>>Phil
>
>
> But the worst case additions of many different varying frequencies and amplitudes
> of a musical signal cannot give rise to a faster rise time than that of a full power
> sine wave signal at the frequency limit of the music bandwidth.
> This bandwidth is about 20 kHz these days, and whatever you do with other waves below
> this F
> the rise time will never be faster than that in a 20kHz full power sine wave.
> If anything happens at a faster rate, ie, the slope of the wave graph is steeper
> than that of a 20kHz wave then there are higher F present which are above 20kHz.
>
> If what you are suggesting is possible, then such manifestations of higher frequencies
> above 20kHz
> could easily be filtered out and proved to exist.
>
> Foe example if the amp produces 2H and 3H of say 20kHz, then indeed the 40hHz and 60kHz
>
> would become real, and the IMD product between say 8kHz and 18kHz of 26kHz would become
>
> real, providing the amp has the capacity to pass the higher F.
> Usually most amps can do this because such spuriae above 20kHz are low in level.
>
> Patrick Turner.
>
>
>
In the first place, this is a minor point which states that you cannot
take a single, typical 20 KHz wave, and assume that that contains the
highest slew rate you will see. But any text will show that when you mix
two sinusoids of the same or different frequencies, you get additive and
subtractive effects, so this is really, really old news. Will the
maximum rates exceed that of a full-power 20 KHz wave? I have to admit,
I don't know for certain, but I *think* the answer is actually yes,
which was one of the reasons why some older high feedback transistor
amps got into trouble; they made assumptions about the maximum slew rate
they would get hit with that were false. Perhaps Otala's older papers on
TIM will provide measurements of actual, rather than theoretical, max
slew rates. Still, as much as I hate to admit it, you may be right on
what we can *safely* assume the max slew rate to be, and I was indeed
thinking that LP audio signals occasionally exceeded this value.

Humbled Phil

[Eeyore]

Phil wrote:

> Tom A. wrote:
>
> > I only know Matti Otala from being the designer of a particular set of
> > top of the range Harman Kardon pre/power amp, that got great reviews in
> > the 80s. I might be mistaken, but isn't he the designer of several well
> > regarded Electrocompaniet amps?
> >
> > Here is a link to pictures of the HK set:
> > http://www.popolo.com/citation.html
> >
> > Tom
> >
> That is indeed the Citation XX, the one he designed after he did the
> analysis on feedback. Supposed to sound fantastic, if you can find one.

Probably very good for its time. Many better ideas have happened since. I have
actually adopted some of Otala's thinking in my own designs actually.

Graham

[Phil]

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

[Andre Jute]

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.

[Andre Jute]

ADDENDUM: The threads in which the argument referred to below was
carried on are "Negative Feedback in Triodes: The Logical and
Experimental Proof" which starts here:

http://groups.google.ie/group/rec.audio.tubes/tree/browse_frm/thread/3a0c1bfbddedf1a8/43dff8d8ed263a35?rnum=1&hl=en&_done=%2Fgroup%2Frec.audio.tubes%2Fbrowse_frm%2Fth read%2F3a0c1bfbddedf1a8%2F8bb2abfd88ae6fa9%3Fhl%3D en%26#doc_43dff8d8ed263a35

and "Dynamic phase shift" which starts here:

http://groups.google.ie/group/rec.audio.tubes/tree/browse_frm/thread/28693a73b0de672f/528334cd3113f1ab?rnum=1&hl=en&_done=%2Fgroup%2Frec.audio.tubes%2Fbrowse_frm%2Fth read%2F28693a73b0de672f%2F8b591261057650e6%3Fhl%3D en%26#doc_528334cd3113f1ab

--AJ

Andre Jute wrote:
> 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.

[Andre Jute]

And, after all that, we still seek an answer, in the new thread "The
sound of excessive negative feedback" which starts here:

http://groups.google.ie/group/rec.audio.tubes/tree/browse_frm/thread/91d2c44230eae092/eeb301e147c56a8b?rnum=1&hl=en&_done=%2Fgroup%2Frec.audio.tubes%2Fbrowse_frm%2Fth read%2F91d2c44230eae092%2Feeb301e147c56a8b%3Fhl%3D en%26#doc_eeb301e147c56a8b

Andre Jute wrote:
> ADDENDUM: The threads in which the argument referred to below was
> carried on are "Negative Feedback in Triodes: The Logical and
> Experimental Proof" which starts here:
>
> http://groups.google.ie/group/rec.audio.tubes/tree/browse_frm/thread/3a0c1bfbddedf1a8/43dff8d8ed263a35?rnum=1&hl=en&_done=%2Fgroup%2Frec.audio.tubes%2Fbrowse_frm%2Fth read%2F3a0c1bfbddedf1a8%2F8bb2abfd88ae6fa9%3Fhl%3D en%26#doc_43dff8d8ed263a35
>
> and "Dynamic phase shift" which starts here:
>
> http://groups.google.ie/group/rec.audio.tubes/tree/browse_frm/thread/28693a73b0de672f/528334cd3113f1ab?rnum=1&hl=en&_done=%2Fgroup%2Frec.audio.tubes%2Fbrowse_frm%2Fth read%2F28693a73b0de672f%2F8b591261057650e6%3Fhl%3D en%26#doc_528334cd3113f1ab
>
> --AJ
>
> Andre Jute wrote:
> > 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.

[paul packer]

On Sat, 9 Sep 2006 15:02:13 +1000, "Phil Allison"
> wrote:

>
>"Phil"
>
>>
>> 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.
>
>
>
>
>
>....... Phil


You have a heart as big as all outdoors, Phil.

[Phil]

Eeyore wrote:
>
> Phil wrote:
>
>
>>Tom A. wrote:
>>
>>
>>>I only know Matti Otala from being the designer of a particular set of
>>>top of the range Harman Kardon pre/power amp, that got great reviews in
>>>the 80s. I might be mistaken, but isn't he the designer of several well
>>>regarded Electrocompaniet amps?
>>>
>>>Here is a link to pictures of the HK set:
>>>http://www.popolo.com/citation.html
>>>
>>>Tom
>>>
>>
>>That is indeed the Citation XX, the one he designed after he did the
>>analysis on feedback. Supposed to sound fantastic, if you can find one.
>
>
> Probably very good for its time. Many better ideas have happened since. I have
> actually adopted some of Otala's thinking in my own designs actually.
>
> Graham
>
You have designs? I would love to see them, even if it requires
promising to NOT comment on them ... ;-)

Phil

[Chris Hornbeck]

On Sat, 09 Sep 2006 11:27:49 GMT, Phil >
wrote:

>I would love to, but I REALLY want to read the paper he wrote, or at
>least presented, referred to here, and not just his previous papers.
>I've looked in JAES, and there's nothing (although I think the older
>papers are there). Any ideas on how to find something like a collection
>of his papers?

Email me a USPS address.

All good fortune,

Chris Hornbeck
"Man is the measure of all things. Sigh.
Happy Ears!" -Al

[Sander deWaal]

Tom A. > said:


>I only know Matti Otala from being the designer of a particular set of
>top of the range Harman Kardon pre/power amp, that got great reviews in
>the 80s. I might be mistaken, but isn't he the designer of several well
>regarded Electrocompaniet amps?


Yep. A horror to repair, and they failed quite often.

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

[Eeyore]

Sander deWaal wrote:

> Tom A. > said:
>
> >I only know Matti Otala from being the designer of a particular set of
> >top of the range Harman Kardon pre/power amp, that got great reviews in
> >the 80s. I might be mistaken, but isn't he the designer of several well
> >regarded Electrocompaniet amps?
>
> Yep. A horror to repair, and they failed quite often.

You've been there too ?

I totally agree.

Graham

[Sander deWaal]

Eeyore > said:


>> >..... Electrocompaniet amps?


>> Yep. A horror to repair, and they failed quite often.


>You've been there too ?


Yup. They sounded OK though, and I liked the looks of the
"anniversary" series with the Norwegian marble front panels.

Many of them went to Asia, as a collector's item.

Good riddance ;-)

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

[ScottW]

"Phil" > wrote in message
...
> Patrick Turner wrote:
>
>>
>> Phil wrote:
>>
>>
>>>Eeyore wrote:
>>>
>>>>Phil wrote:
>>>>
>>>>
>>>>
>>>>>Eeyore wrote:
>>>>>
>>>>>
>>>>>>For any sinewave ( see Fourier theory for applicability ) the max slew
>>>>>>rate ( at
>>>>>>zero crossing btw ) is 2.pi.f.Vpeak.
>>>>>>
>>>>>>For a 20kHz signal of say 2V peak amplitude that means a slew rate of
>>>>>>0.25 V/us
>>>>>>! Even a rubbish 741 or 1458 can manage that !
>>>>>>
>>>>>>Given that modern audio op-amps are capable of slew rates of ~ 10V/us -
>>>>>>you're
>>>>>>never even remotely close to slew limited anything.
>>>>>>
>>>>>>Graham
>>>>>
>>>>>Well, remember, the maximum slew rate found in audio signals is much
>>>>>greater than what a theoretical 20 KHz signal is going to supply,
>>>>
>>>>
>>>>Utter drivel.
>>>>
>>>>Learn some science before posting such ********.
>>>>
>>>>bye bye.
>>>>
>>>>Graham
>>>>
>>>
>>>I'll tell you what, why don't you take one point that you can attack,
>>>ignore everything else, and then put out yet another unsupported
>>>criticism. In audio, where you have a huge mixture of signals, the
>>>waveforms periodically add together, momentarily increasing the slew
>>>rate over what a typical -- read, very small amplitude -- audio 20 KHz
>>>signal would have. Do you disagree with that? Would you like to state
>>>here, for the public record, that you think that when several signals
>>>are mixed, that there are no momentary peaks in slew rate which exceed
>>>the maximum slew rate found in individual signals? By all means, show
>>>everyone here how well you think, and reason, and how much you actually
>>>understand about audio. Oh, BY THE WAY, do you have anything intelligent
>>>and useful to say about the rest of my comments? Useless cheap shots do
>>>not qualify ...
>>>
>>>Phil
>>
>>
>> But the worst case additions of many different varying frequencies and
>> amplitudes
>> of a musical signal cannot give rise to a faster rise time than that of a
>> full power
>> sine wave signal at the frequency limit of the music bandwidth.
>> This bandwidth is about 20 kHz these days, and whatever you do with other
>> waves below
>> this F
>> the rise time will never be faster than that in a 20kHz full power sine wave.
>> If anything happens at a faster rate, ie, the slope of the wave graph is
>> steeper
>> than that of a 20kHz wave then there are higher F present which are above
>> 20kHz.
>>
>> If what you are suggesting is possible, then such manifestations of higher
>> frequencies
>> above 20kHz
>> could easily be filtered out and proved to exist.
>>
>> Foe example if the amp produces 2H and 3H of say 20kHz, then indeed the 40hHz
>> and 60kHz
>>
>> would become real, and the IMD product between say 8kHz and 18kHz of 26kHz
>> would become
>>
>> real, providing the amp has the capacity to pass the higher F.
>> Usually most amps can do this because such spuriae above 20kHz are low in
>> level.
>>
>> Patrick Turner.
>>
>>
>>
> In the first place, this is a minor point which states that you cannot take a
> single, typical 20 KHz wave, and assume that that contains the highest slew
> rate you will see. But any text will show that when you mix two sinusoids of
> the same or different frequencies, you get additive and subtractive effects,
> so this is really, really old news. Will the maximum rates exceed that of a
> full-power 20 KHz wave? I have to admit, I don't know for certain, but I
> *think* the answer is actually yes,

Not without exceeding "full-power"...and then you'd clip anyway.

ScottW

[Chris Hornbeck]

On Sat, 9 Sep 2006 18:28:52 -0700, "ScottW" >
wrote:

>> In the first place, this is a minor point which states that you cannot take a
>> single, typical 20 KHz wave, and assume that that contains the highest slew
>> rate you will see. But any text will show that when you mix two sinusoids of
>> the same or different frequencies, you get additive and subtractive effects,
>> so this is really, really old news. Will the maximum rates exceed that of a
>> full-power 20 KHz wave? I have to admit, I don't know for certain, but I
>> *think* the answer is actually yes,
>
> Not without exceeding "full-power"...and then you'd clip anyway.

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.

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

There will also be a threshold where an amplifier *with* feedback
will slew. If there are no other differences between the
amplifiers, these two levels will be *the same*.

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.

The issue of slew-limiting in amplifiers arose because
amplifiers with feedback must sacrifice some slewing ability
to the altar of stability. (Many, many qualifiers need be
inserted here; whole 'nother can 'a worms. But we're
talking about a thirty year gone issue.) In the early dark
days of semiconductor amplifiers, compromises for stability
were so demanding as to damage signal in the passband at
ordinary levels.




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.

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". The
term itself is snake oil of the highest grade.

All good fortune,

Chris Hornbeck
"When you look long into the abyss, the abyss also looks into you."
-Friedrich Nietzsche, _Beyond Good and Evil_

[Phil Allison]

"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

[Phil Allison]

"Eeyore"
>
> I've had to repair one those Electrocompianets several times. It may have
> been a
> good design but the implementation was shockingly bad. It hummed a lot
> too.



** This web page has some startling inside revelations on the saga of the
Electrocompaniet.

http://home.online.no/~tsandstr/OtalaStory.htm


Quote:
So, we realised than the balance of distortions were the essential factor to
consider. Not only do you have to balance THD against TIM, but also low
frequency distortion against high frequency distortion, frequency and phase
response against non-linear distortion in general, and so on.

This insight triggered the Great Change:

One night (it always happened at night times!) we increased the feedback
10dB, to a total amount of 30dB feedback. The sound improvement was
staggering!!! And, contrary to common belief in our own community !





** Their great discovery = more NFB sounds better !!

ROTFLMAO !!!!!





........ Phil

[Phil]

Phil Allison wrote:

> "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
>
>
Sorry, I have to give you grief as long as possible. But look at it this
way; you, Phil Allison, give meaning, true meaning, to someone's life. <-:

Yours truly,
Phil

[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/libiscv/libisenglCVotala.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

[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/libiscv/libisenglCVotala.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/libiscv/libisenglCVotala.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

[paul packer]

On Wed, 13 Sep 2006 11:43:36 +1000, "Phil Allison"
> wrote:


>> i'd call that a massive generalisation.
>
>
> ** I'd call YOU a massive ****WIT !!!


But since you've called everyone that at one time or another, it
probably doesn't mean much.

[Patrick Turner]

Phil Allison wrote:

> "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.

Backing your self up without any respect to what anyone else says is exactly
your style and prooves
your debating methods are quite inadequately convincing to anyone with a brain.

I routinely make OPTs which allow 40dB+ of applied global NFB at the mid
frequency.
But there is a stablity margin of at least 15 dB at 20Hz and 20kHz,
so that at least 30 dB of NFB can be applied at the end of the AF band.
Stabilizing networks allow any vaue of capacitance tpo be connected across the
output terminals
without a resistive load and stbility is maintained.
There is NO NEED to apply any more NFB than I do in a tube amp and that is the
reason
why I don't, and its not because I cannot apply any more than 16 dB.

There have been many amps with inadquate amounts of LP and hube amounts of
leakage L
and shunt C and these will produce a small margin of stability with NFB but I
don't make
OPTs like the crummy types fitted to so many commercially made products such as
old Leaks etc.

Save the next hissy fit for someone else Phil because calling names doesn't
work, except
to make you look exactly what you have called me.
This time YOU are incorrect, so get used to it.

And when replying, try not to snip so much relevant information the group
may be interested in.

Patrick Turner.




>
>
> ....... Phil

[Patrick Turner]

Phil Allison wrote:

> "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.

You are Wrong Again and 26dB was a routine amount of NFB used in Mullard 520
with a Partridge OPT and if you study the amps by ARC and CJ and many other
names
you will find they use lots more than 20 dB of global NFB.
The top brand names tried often to have their products measure as well as
possible because the market
amoung conservative middle aged men is one where many of these guys
don't feel comfortable with lousy measurements regardless of the subjective
perceptions which are often beyond their capability to make with any meaning or
accuracy.
0.05% THD at a kHz at 1 dB below clipping at 50 watts meant that listening
levels
gave around 0.01% THD.... AND... very low phase shift.

There was a strong urge to get the measured thd below 0.1% at clipping in many
tube amps
and to get the phase shift less than +/- 10 degrees at each end of the AF band.

Check out the original design data by D.T.N Williamson and McIntosh.

Not much to whinge about.

Patrick Turner.

>
>
> ....... Phil

[Phil Allison]

"Patrick Turner"

>
>> ** 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.
>
> You are Wrong Again and 26dB was a routine amount of NFB used in Mullard
> 520
> with a Partridge OPT and if you study the amps by ARC and CJ and many
> other
> names


** What nit picking ********.

SS amps typically use over 60 dB of NFB to *eliminate* harmonic distortion.

Unlike any tube amp with an OT, negative feedback extends over the range
from DC to MHz .




........ Phil

[Phil Allison]

"Patrick Turner" = a totally psycho, transformer winder freak.



Here is what originally I wrote:

----------------------------------------

" 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. "

----------------------------------------

The phrase " **decent amount** " is to be defined in relation to SS amp
norms.

Not bloody tube amp norms, since that begs the question - you imbecile !!


No tube amp with an OT has a damping factor anything like 1000 from DC to
5KHz.

No tube amp with an OT has a THD anything like 0.002 % from DC to 20 KHz,
for life.

And the reason they DO NOT is because of response and particularly PHASE
SHIFT limitations imposed by the OT.

That is why ** were placed around the phrase " decent amount ".


Now, **** the hell off - you criminal POS.





........ Phil

[Patrick Turner]

Phil Allison wrote:

> "Patrick Turner"
>
> >
> >> ** 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.
> >
> > You are Wrong Again and 26dB was a routine amount of NFB used in Mullard
> > 520
> > with a Partridge OPT and if you study the amps by ARC and CJ and many
> > other
> > names
>
> ** What nit picking ********.

You made a serious error in your posts which I have pointed out.

At normal listening levels a well made tube amp working in class A has THD
less than 0.02%, ie, a pair of KT88/6550 in PP with 16dB global NFB
and at a watt where max po = 40+ watts.

This THD if it were played through a speaker without the wanted undistorted
signal
would be inaudible, and therefore eliminated.
But of course the ability of people to detect THD is at a threshold 20 dB or
more above
the 0.02% levels.

>
>
> SS amps typically use over 60 dB of NFB to *eliminate* harmonic distortion.

Yes, and I have built SS amps which have less than 0.01% at 250 watts.
So what? I know of nobody who detects that a better measuring SS amp
has less THD than tube amp of average quality, and where the playing field of
comparison is level, ie,
we are testing a 50 watt SS amp with a 50 watt tube amp.

>
>
> Unlike any tube amp with an OT, negative feedback extends over the range
> from DC to MHz .

There is no NEED for the NFB to extend from DC to MHz.

We can only hear from about 20Hz to 15kHz.

Bandwidth up to MHz can be a real problem because of the inevitable
phase shift of reactive loads so SS amps become unstable at RF insted of at
about between
80kHz and 300kHz for a tube amp if poorly made.
Who cares if a reduced amount of NFB is effective at 20kHz?
The first artifact is the second harmonic at 40kHz.

Virtually all SS amps have enormous open loop gain at say about 500Hz and then
it rolls off
at 6 dB/octave above 500Hz, so the amount of applied FB also rolls off
above 500Hz where indeed the applied global NFB is 60 dB but not at 50kHz where
it is
perhaps 40dB less or more especially if the HF gain has been reduced by a zobel
network
in the input stages.

Nearly all SS amps have an RC Zobel from the output and NFB take off point to
0V
to prevent the follower output stage having too much gain internally.
Then there is usually an L&R series network between the NFB take off and the
load
to prevent the effect of capacitive loads from
causing impossible current levels on transients.
The signal at the speaker is thus slightly indirectly coupled to the amp and
its FB, ie, its filtered,
and the LR can cause a lot of ringing on square waves, rather like the leakage
inductance
causes ring in the similar manner.

In any case THD is NOT eliminated by any amp although it can be reduced below
the noise floor.
Halcro amps get extraordinarily low thd measures of 0.0001% at 200 watts and
declining proportionately
with output voltage so thd cannot easily be measured at a watt.
THis does not mean that all the many amps which measure 10x 100x or 1,000x
times worse
should all be binned.

I just don't hear any huge sonic improvement by reducing THD below 0.02%
and reducing the accompanying and worse problems of IMD.

THD is a rather innocent artifact because most THD products merely add or
subtract
a tiny % to the existing huge number of harmonics in music.
The related IMD products are the real worry because the interaction between
different tones produces tones which are not necessarily harmonic with the
music's
harmonics, and the IMD manifests itself in a kind of grating noise in the
backgound
of the music, something that some SS amps are prone to despite measuring
reasonably
well with THD into an R load with a single tone of 1 kHz.
Pentode amps without NFB sound awful as well if used for repropucing music
accurately,
but not if used as part of the instrument as a musician does; the more
harmonics and artifacts including some mains buzz, and the rock stars think its
great.

Interaction between say 18kHz and 17kHz will produce sum and difference F of
35kHz and 1 kHz. The 1 kHz could be heard if levels were high enough to start
with and the
amp of poor quality, but in music levels of HF are low.

The IMD levels produced in the 1947 Williamson amp when used with any music for
an average level
of 0.5 watts into speakers of the day at 96dB efficient was negligible, and
all the sources had MORE IMD than the amplifier was producing, and probably the
speakers.

If we use a quad of KT88 instead of a pair of lousy KT66 today,
the amp IMD is quite low enough to be inaudible with moderate NFB applied.

If you want to built an amp without any global NFB and use a single triode,
the result can measure within existing known hi-fi standards.

Loop NFB may be used, but it is never been compulsory in triode amps.
It is compulsory with SS amps, since there is no internal NFB within a basic SS
device
like there is in a triode.

Patrick Turner.










>
>
> ....... Phil

[Phil Allison]

"Patrick Turner" = totally psycho, transformer winding room temp cretin

>>
>> >> ** 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.
>> >
>> > You are Wrong Again and 26dB was a routine amount of NFB used in
>> > Mullard
>> > 520
>> > with a Partridge OPT and if you study the amps by ARC and CJ and many
>> > other
>> > names
>>
>> ** What nit picking ********.
>
> You made a serious error


** What INSANE ********.

The NFB ratio of most SS amps is 60 dB or more !!

Cos there is no damn output transformer to worry about.




........ Phil

[Patrick Turner]

Phil Allison wrote:

> "Patrick Turner" = a totally psycho, transformer winder freak.
>
> Here is what originally I wrote:
>
> ----------------------------------------
>
> " 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. "
>
> ----------------------------------------
>
> The phrase " **decent amount** " is to be defined in relation to SS amp
> norms.

Ah, so now to try to gain credibility for your original statements
you invent conditions and definitions AFTER being justifiably
criticised by myself.

>
>
> Not bloody tube amp norms, since that begs the question - you imbecile !!
>
> No tube amp with an OT has a damping factor anything like 1000 from DC to
> 5KHz.

There is zero need for DF to be 1,000.

All speakers have a dc component in their DC resistance of crossover coils etc
and thus the series R component will eclipse attempts at betterment
by having the Rout of the amp at 1/1,000 of the speaker load value.

There is no need for Rout to be less than 1/10 of the minimum load value.

>
>
> No tube amp with an OT has a THD anything like 0.002 % from DC to 20 KHz,
> for life.

There is no need for THD to be 0.002%.

If the output level is 2.83Vrms or one watt into 8 ohms,
0.002% is 5.66 uV, and rather hard to hear if played alone into any speaker.
0.2% is only 5.66 mV, and inaudible to most folks.


>
> And the reason they DO NOT is because of response and particularly PHASE
> SHIFT limitations imposed by the OT.

SS amps have phase shift at HF and if enough NFB is applied they can go unstable

but at a higher F than with a tube amp.
I have seen plenty of SS amps which displayed oscillations at some RF
because of the applied FB and phase shift.

There is no need to apply much NFB around most well made tube amps
because the open loop BW is usually 10Hz to 50kHz with open loop
phase shift less than +/- 90 degrees at those F, and the THD
is less than 2% at full power open loop.
Therefore with 20dB of NFB the phase shift, response, and THD is all improved by

10 times, and there is no justification to exclude tube amp measurements from
being
OK because they do not comply with YOUR ideas of what constitutes a "decent
amount" .


>
> That is why ** were placed around the phrase " decent amount ".

Your "decent amount" is your own invention to save your hide.

You are sounding worse than Trevor Wilsom when trying to present the facts.

>
>
> Now, **** the hell off - you criminal POS.

I WILL REMAIN HERE TO CORRECT YOUR BS.

You don't often BS, but when you do, it needs to be pointed out.

Patrick Turner.



>
>
> ....... Phil

[George M. Middius]

Patrick Turner said:

> > Now, **** the hell off - you criminal POS.

> I WILL REMAIN HERE TO CORRECT YOUR BS.
> You don't often BS, but when you do, it needs to be pointed out.

What on earth is wrong with this "Phil Allison" person?





--

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

[Phil Allison]

"Patrick Turner" = a totally psycho, transformer winder freak.


Here is what originally I wrote:

----------------------------------------

" 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. "

----------------------------------------

The phrase " **decent amount** " is to be defined in relation to SS amp
norms.

Not bloody tube amp norms, since that begs the question - you ****ING
imbecile !!

No tube amp with an OT has a damping factor anything like 1000 from DC to
5KHz.

No tube amp with an OT has a THD anything like 0.002 % from DC to 20 KHz,
for life.

And the reason they DO NOT is because of response and particularly PHASE
SHIFT limitations imposed by the OT.

That is why ** were placed around the phrase " decent amount ".


Now, **** the HELL OFF -

you damn CRIMINAL PSYCHOPATH





........ Phil

[Phil Allison]

"Patrick Turner"

> If the output level is 2.83Vrms or one watt into 8 ohms,
> 0.002% is 5.66 uV,


** ******** !!

The autistic cretin cannot do basic math.


> and rather hard to hear if played alone into any speaker.
> 0.2% is only 5.66 mV, and inaudible to most folks.


** MORE ********.





....... Phil

[Patrick Turner]

Phil Allison wrote:

> "Patrick Turner" = totally psycho, transformer winding room temp cretin
>
> >>
> >> >> ** 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.
> >> >
> >> > You are Wrong Again and 26dB was a routine amount of NFB used in
> >> > Mullard
> >> > 520
> >> > with a Partridge OPT and if you study the amps by ARC and CJ and many
> >> > other
> >> > names
> >>
> >> ** What nit picking ********.
> >
> > You made a serious error
>
> ** What INSANE ********.
>
> The NFB ratio of most SS amps is 60 dB or more !!

Yes I agree with this last sentance.
You imply that 60dB is a great achievement but 40dB would be fine,
or even 20dB if the amp was a in class A.

>
>
> Cos there is no damn output transformer to worry about.

And none to worry about in a tubed OTL amp either, where
40 db of NFB is commonly used because the Rout is so abysmally high,
and the tubes are forced to work with loads they are not meant to work with
and in class B.

The global NFB around a bjt amp is needed to mainly reduce THD from about
5% at clipping without the global. The crossover Dn and attrocious other
output stage artifacts are
dealt with usually with the emitter follower connection which is local NFB
equal to about 40dB, so in fact a lot MORE total NFB is needed for
an SS amp to force it to measure how they do.

I am not against vast amounts of NFB in SS amps because i find that its so
easy to
use and gain is so abundant and the sound does not suffer from the huge amount
of NFB.
But after having conducted AB tests between the better tube amps AND SS amps
which I have
designed and constructed and as detailed at my website I find that most ppl
have difficulty telling me of any real sonic differences.

I have used only mild NFB in my class A 50 watt mosfet based monoblocs with
OPTs with 10Hz to 300kHz BW as one does in a tube amp
and although THD is 0.2% at 40+ watts, there is no improvement when moving to
a 300 watt amp with 1/100 of the THD, and no OPT.

Many ppl prefer SET and SEUL amps with much more THD over what they find
with better SS amps like Musical Fidelity which sounds so clinical and dull.

I don't worry about the OPT because the ones I make have
extraordinary bandwidth and able to be used with much more NFB than is
required.

Patrick Turner.

>
>
> ....... Phil

[Patrick Turner]

I will not **** off.

Your unjustified criticisms of OPTs has gotten you into hot water.

You have little idea of what is possible with an OPT because you have never
designed and wound one
and are used to the crummy varieties found in guitar amps and budget crap which
cannot sustain
much applied FB.

But in the best brands of h-fi tube amps the OPT bandwidth has been extended
and phase shift reduced to enable an adequate amount of NFB to be applied
to have the amp conform to standard hi-fidelity standards.

Patrick Turner.



Phil Allison wrote:

> "Patrick Turner" = a totally psycho, transformer winder freak.
>
> Here is what originally I wrote:
>
> ----------------------------------------
>
> " 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. "
>
> ----------------------------------------
>
> The phrase " **decent amount** " is to be defined in relation to SS amp
> norms.
>
> Not bloody tube amp norms, since that begs the question - you ****ING
> imbecile !!
>
> No tube amp with an OT has a damping factor anything like 1000 from DC to
> 5KHz.
>
> No tube amp with an OT has a THD anything like 0.002 % from DC to 20 KHz,
> for life.
>
> And the reason they DO NOT is because of response and particularly PHASE
> SHIFT limitations imposed by the OT.
>
> That is why ** were placed around the phrase " decent amount ".
>
> Now, **** the HELL OFF -
>
> you damn CRIMINAL PSYCHOPATH
>
> ....... Phil

[Patrick Turner]

Phil Allison wrote:

> "Patrick Turner"
>
> > If the output level is 2.83Vrms or one watt into 8 ohms,
> > 0.002% is 5.66 uV,
>
> ** ******** !!
>
> The autistic cretin cannot do basic math.

You offer no correction, just insults, but OK, I made a slight mistake
in the math.

0.002% is 0.00002 x 2.83V = 56.6 uv, and this would NOT be audible.
0.2% is 0.002 x 2.83V = 5.66 mV, which is correct, no?...
and is also inaudible as would 0.02%, typical for a well made tube amp
at a watt.

>
>
> > and rather hard to hear if played alone into any speaker.
> > 0.2% is only 5.66 mV, and inaudible to most folks.
>
> ** MORE ********.

Next time you have a pure sine wave feeding a speaker add 0.2% of 2H or
3H
and see if you hear anything.

These harmonics are usually always the largest present in most amp
artifact list.
but most well made tube amps have 0.02% at 1 watt, which is a loud 90dB
SPL from
most modern speakers and I know you cannot hear that 0.02%.

When you say ******** to me, I hear that you are bull****ting.

Patrick Turner.



>
>
> ...... Phil

[[email protected]]

On Thu, 14 Sep 2006 00:27:37 +1000, "Phil Allison" >
wrote:

>
>"Patrick Turner" = totally psycho, transformer winding room temp cretin
>
>>>
>>> >> ** 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.
>>> >
>>> > You are Wrong Again and 26dB was a routine amount of NFB used in
>>> > Mullard
>>> > 520
>>> > with a Partridge OPT and if you study the amps by ARC and CJ and many
>>> > other
>>> > names
>>>
>>> ** What nit picking ********.
>>
>> You made a serious error
>
>
> ** What INSANE ********.
>
>The NFB ratio of most SS amps is 60 dB or more !!
>
>Cos there is no damn output transformer to worry about.
>
>
>
>
>....... Phil
>
>

Plus the fact that a bunch of 500 beta transistors in cascade will give you a
gain in the billions! Most power amps have a voltage gain requirement closer to
10... feedback is necessary if you don't want noisy attenuator circuits...

[paul packer]

On Wed, 13 Sep 2006 10:40:34 -0400, George M. Middius <cmndr
[underscore] george [at] comcast [dot] net> wrote:

>
>
>Patrick Turner said:
>
>> > Now, **** the hell off - you criminal POS.
>
>> I WILL REMAIN HERE TO CORRECT YOUR BS.
>> You don't often BS, but when you do, it needs to be pointed out.
>
>What on earth is wrong with this "Phil Allison" person?


How long have you got, George?

[Car]

paul packer wrote:
> On Sat, 9 Sep 2006 15:02:13 +1000, "Phil Allison"
> > wrote:
>
>> "Phil"
>>
>>> 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.
>>
>>
>>
>>
>>
>> ....... Phil
>
>
> You have a heart as big as all outdoors, Phil.


Go to: http://www.cancer-coverup.com/fighters/cesium-science.htm

You may find some hope for your situation, it is your choice.

Good luck.

[Arny Krueger]

"paul packer" > wrote in message
...
> On Wed, 13 Sep 2006 10:40:34 -0400, George M. Middius <cmndr
> [underscore] george [at] comcast [dot] net> wrote:
>
>>
>>
>>Patrick Turner said:
>>
>>> > Now, **** the hell off - you criminal POS.
>>
>>> I WILL REMAIN HERE TO CORRECT YOUR BS.
>>> You don't often BS, but when you do, it needs to be pointed out.
>>
>>What on earth is wrong with this "Phil Allison" person?

> How long have you got, George?

Why not start out by telling us what's wrong with George and yourself, Paul?

[Phil Allison]

"paul packer"
>
>>What on earth is wrong with this "Phil Allison" person?
>
>
> How long have you got, George?


** Long enough to telephone NSW Australia ??

Try: 13 Tosca Drive Gorakan

(02) 4392 5924 ...... ask for Gladys


Or if that fails, try

13A Tosca Drive Gorakan,

(02) 4393 9920

and ask for Paul ( aka Edward)



Enjoy............






....... Phil

[paul packer]

On Thu, 14 Sep 2006 22:39:35 +1000, "Phil Allison"
> wrote:

>
>"paul packer"
>>
>>>What on earth is wrong with this "Phil Allison" person?
>>
>>
>> How long have you got, George?
>
>
>** Long enough to telephone NSW Australia ??
>
> Try: 13 Tosca Drive Gorakan

It's Gorokan, Phil. How many times!!!

> (02) 4392 5924 ...... ask for Gladys

And say what? He doesn't know Gladys and neither do you.
For the record, Gladys is my 85 year old widowed mother, and anyone
disturbing her with an unnecessary or harassing phone call would
indeed be playing a dangerous game.

> Or if that fails, try
>
> 13A Tosca Drive Gorakan,

Gorokan, Phil. How many times!!!

> (02) 4393 9920
>
> and ask for Paul ( aka Edward)

Ha! Your netstalking is on the nose, Phil. No one called Paul (or
Edward) lives at 13a. And I have never been known as anything but
Paul.

Incidentally, have you moved lately, Phil? If not we all know where
you live should we need to pay you a visit, individually or
collectively.

[Arny Krueger]

"paul packer" > wrote in message
...
> On Thu, 14 Sep 2006 22:39:35 +1000, "Phil Allison"
> > wrote:
>
>>
>>"paul packer"
>>>
>>>>What on earth is wrong with this "Phil Allison" person?
>>>
>>>
>>> How long have you got, George?
>>
>>
>>** Long enough to telephone NSW Australia ??
>>
>> Try: 13 Tosca Drive Gorakan
>
> It's Gorokan, Phil. How many times!!!

Note that in Paul's world, anything that isn't spelled perfectly right is
dismissed out-of-hand unless it was posted by one of his cronies.

[paul packer]

Arny Krueger wrote:
> "paul packer" > wrote in message
> ...
> > On Thu, 14 Sep 2006 22:39:35 +1000, "Phil Allison"
> > > wrote:
> >
> >>
> >>"paul packer"
> >>>
> >>>>What on earth is wrong with this "Phil Allison" person?
> >>>
> >>>
> >>> How long have you got, George?
> >>
> >>
> >>** Long enough to telephone NSW Australia ??
> >>
> >> Try: 13 Tosca Drive Gorakan
> >
> > It's Gorokan, Phil. How many times!!!
>
> Note that in Paul's world, anything that isn't spelled perfectly right is
> dismissed out-of-hand unless it was posted by one of his cronies.

Tautology! "perfectly", "right".

[Ian Iveson]

Paul Packer wrote:

> Tautology! "perfectly", "right".

In this context, yes, but don't get carried away with the idea.

cheers, Ian

[Phil]

Joseph Meditz wrote:
> 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
>
Sorry about that, I keep forgetting to add that you have to remove my
head to email me off-list.

Yes, I think you and Phil Allison are right on this one. I could have
sworn that the speaker books say that the high frequency components do
not have a "phase-smear" caused by the low frequency excursions of the
cone, due to "something" (I thought because the *ratio* of movements in
the mic cancelled out the *ratio* in the speaker). Even before I looked
in the books, however, thinking about what Phil said, it became obvious
that he is right, there is definitely a time-smearing of the high
frequency signals due to the low frequency movements of the cone. I then
thought "Wow, the books are wrong!" but I can't anything in the books on
it, so that obviously is my bad, alone. Okay, I hate to say it, but
Phil, you were RIGHT, and I was WRONG, period. So, is this one reason
why *good* horn systems sound so much more lifelike, and especially have
more *impact*, because the much smaller excursions result in less
time-smearing of the HF signals?

Phil

[Phil Allison]

"Phil"
>
> Yes, I think you and Phil Allison are right on this one. I could have
> sworn that the speaker books say that the high frequency components do not
> have a "phase-smear" caused by the low frequency excursions of the cone,
> due to "something" (I thought because the *ratio* of movements in the mic
> cancelled out the *ratio* in the speaker). Even before I looked in the
> books, however, thinking about what Phil said, it became obvious that he
> is right, there is definitely a time-smearing of the high frequency
> signals due to the low frequency movements of the cone. I then thought
> "Wow, the books are wrong!" but I can't anything in the books on it, so
> that obviously is my bad, alone. Okay, I hate to say it, but Phil, you
> were RIGHT, and I was WRONG, period. So, is this one reason why *good*
> horn systems sound so much more lifelike, and especially have more
> *impact*, because the much smaller excursions result in less time-smearing
> of the HF signals?


** Not at all.

Nearly all hi-fi speakers are 2 or 3 way designs, which eliminates the
issue.

Horrible full range driver designs like the Bose 901 suffer from very
obvious IM distortion when played at highish volume.

In known examples of full ranger drivers, IM products exceed the induced
phase shift products in amplitude by an order of magnitude, at least.

Dynamic phase shift ( aka Doppler distortion) does exist, but is practically
immeasurable & inaudible since it is buried under a much worse distortion.

Nothing to do with amplifiers, whatsoever.




........ Phil

[Phil]

Car wrote:
> paul packer wrote:
>
>> On Sat, 9 Sep 2006 15:02:13 +1000, "Phil Allison"
>> > wrote:
>>
>>> "Phil"
>>>
>>>> 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.
>>>
>>>
>>>
>>>
>>>
>>> ....... Phil
>>
>>
>>
>> You have a heart as big as all outdoors, Phil.
>
>
>
> Go to: http://www.cancer-coverup.com/fighters/cesium-science.htm
>
> You may find some hope for your situation, it is your choice.
>
> Good luck.

Damned interesting! It might be a case of correlation, rather than
causation, meaning that the true cause of low cancer rates could be due
to another factor that is also present, but I think it's worth checking
out. One thing you figure out if you have some disease long enough is
that the medical community has some, but not all, of the important facts
concerning both the true nature of various problems, and the best
solutions. In other words, I have learned the HARD WAY to (1) listen to
everything my doctors tell me, and (2) take their words with a grain of
salt, and research the problem/proposed solution myself. It pays off an
unreasonably high percentage of the time, considering the amount of
money we pay to the medical system. Mind you, I blame the system more
than the doctors, as we basically expect each doctor to do his/her own
research into every issue, instead of having many teams at a national
level, with no restraints from the FDA or lawyers, research one disease
per team, and then send the results, even if that means several
competing results, to doctors.

Thanks,
Phil

[Phil]

Chris Hornbeck wrote:
> On Sat, 09 Sep 2006 11:27:49 GMT, Phil >
> wrote:
>
>
>>I would love to, but I REALLY want to read the paper he wrote, or at
>>least presented, referred to here, and not just his previous papers.
>>I've looked in JAES, and there's nothing (although I think the older
>>papers are there). Any ideas on how to find something like a collection
>>of his papers?
>
>
> Email me a USPS address.
>
> All good fortune,
>
> Chris Hornbeck
> "Man is the measure of all things. Sigh.
> Happy Ears!" -Al

Chris,

I got the article; very interesting! To think that in '73 he was making
SS power amps with an OPEN loop response of 1 MHz, whoa ... It's not
that I don't think we could improve on his design today, mind you, but
he listed a lot of very interesting points and ideas that definitely
have a place even today. Now if I can just find that cursed paper on the
conversion by the feedback loop of amplitude distortions into
"phase-smearing" (as opposed to the normal phase-shifts that exist at
the low and high frequency limits of the amp). Oh well, I think I know
most of what he was saying, just not the precise amounts as a function
of bandwidth and dB of feedback.

Thanks,
Phil

[Arny Krueger]

"Phil" > wrote in message
...

> I got the article; very interesting! To think that in '73 he was making SS
> power amps with an OPEN loop response of 1 MHz,

No great shakes. It's just a matter of keeping the open loop gain down.
Local feedback works.