Jon Risch distortion test signal

[FLZapped]

A trivial example would be the thermal heating of a power amp (output transistors, emitter resistors, various portions of the PS) with a sustained LF signal such as an organ note,

For how long? 30 minutes? Of course, you're ignoring that most who wish to test this will pre-condition the amp by running pink noise through it for a period of time, like 30 minutes, first.

and then a cymbal crash right afterward compared to just a naked cymbal crash without the prior sustained LF signal. The amp will react differently, and the distortion will be different.

Sounds like an impluse test to me.....

A more esoteric example would be when electrolytic caps are used to couple the AC signal, or in feedback loops, or in portions of the circuity that provide a bias point or operating voltage reference, the DA of the electrolytic cap can become a significant factor, and cause the operating points to vary with signal content and level. It helps to realize that the DA of many electrolytics can be as high as several percent, and some of the modern super miniature electrolytic caps are the worst, with DA in the realm of 10% or higher. This is enough to actually shift the voltages/currents that they are providing a reference for.

Still sounds like an impulse test.....

Usually, examination with a simple single test tone will not reveal these kinds of behavior, but a multitone has enough crest factor and enough slew to push such devices into non-linear operation, similar to the difficult musical portions, and show the distortion occuring. The first example would not be covered as well, but some of it would manifest to some degree.

Hmmmm....still seems like a job for a simple impulse test to me.

Once again, much more simple and elegant means are availble to get the job done that are self-evident in their outcome.

-Bruce

[J Risch]

For how long? 30 minutes? Of course, you're ignoring that most who wish to test this will pre-condition the amp by running pink noise through it for a period of time, like 30 minutes, first.

Tsk, Tsk. For the IHF/FTC style testing, you do the pre-conditioning only for the power rating portion of the test (which has distortion limits), but this is NOT the segment of the test regime where you actually run the distortion test portion for the specs.

Sounds like an impulse test to me.....

A simple single impulse would not evoke the same kind of reaction from the amp as what I described. Not enough sustained energy is demanded, just a quick blip, and it's over.

Besides, how does this three times repeated call for impulse testing jibe with your mantra:
"You only need one tone, no, make that two tones, no, make that one tone, wait a minute.... "

You just shot your self down Bruce. Your stance was that a single frequency HD measurement and/or a single IM measurement, and you now knew what the DUT distortion behavior was. Why would you need to use an impulse if these other two were all that was required?


BTW, there is an interesting paper at AP web site about Nonlinear Distortion, see:

http://www.audioprecision.com/bin/Co...nt_Methods.pdf

"Comparison of Non-linear Distortion Measurement Methods" by Richard Cabot.

His list of 6 things that can increase HF distortion, and 5 things that can increase LF distortion (over the levels present in the midband), pretty much shoots down your contention that a simple linear equation describes the distortion for an audio device.

So does the listing of distortion for the various test circuits he shows the measurement results for.
Note very carefully that NONE of the IM tests measure the same, nor do they correlate entirely with the THD measurements. See Figures 8 thru 17.

We see in this paper that HD levels vary with frequency, and with level, as do IM distortion levels. This pretty much puts to rest your ridiculous contentions as outlined in my post #92 at:
Jon Risch distortion test signal

I fully expect an attempt by you to repeat some of the same tired old claims that have already been thoroughly addressed and rebutted, but that won't change the facts of the matter.
Pretty much every thing you have said about the Phi Spectral multitone test signal is wrong, in error, or irrelevant.

Jon Risch

[FLZapped]

Tsk, Tsk. For the IHF/FTC style testing, you do the pre-conditioning only for the power rating portion of the test (which has distortion limits), but this is NOT the segment of the test regime where you actually run the distortion test portion for the specs.

Just applying a similar methodology to your posting, Jon, never mentioned IHF/FTC. I guess that makes your test invalid too.

A simple single impulse would not evoke the same kind of reaction from the amp as what I described. Not enough sustained energy is demanded, just a quick blip, and it's over.

What you described was an impulse following a sustained envelope, not the two superimposed on them.

[quote]
Besides, how does this three times repeated call for impulse testing jibe with your mantra:
"You only need one tone, no, make that two tones, no, make that one tone, wait a minute.... "

Oh lookie here, no argument, so we're back to the ol' ad hominem attack. I never said that and you know it, Think I'm goign to call you MM the second, or did he learn from you?

You just shot your self down Bruce. Your stance was that a single frequency HD measurement and/or a single IM measurement, and you now knew what the DUT distortion behavior was. Why would you need to use an impulse if these other two were all that was required?

Never said that either, Jon. You're trying to reach outside the scope of the argument here in a vain effort to try and make you test signal viable. I just countered with a much more simple and elegant way of dealing with the problem you presented.

-Bruce

[FLZapped]

BTW, there is an interesting paper at AP web site about Nonlinear Distortion, see:

http://www.audioprecision.com/bin/Co...nt_Methods.pdf

"Comparison of Non-linear Distortion Measurement Methods" by Richard Cabot.

What a waste of time. This paper was nothing more than regurgitation of what is already well known and well documented. I didn't see a single bit of new ground broken. Much like Jung's paper on capacitor distortion. And much like your test signal, this one too takes a large amount of computing power to even hope to get results, nor does it point to being any more accurate than what is already in existance and much easier to implement and interpret.

His list of 6 things that can increase HF distortion, and 5 things that can increase LF distortion (over the levels present in the midband),

And nothing new in the lot of them. Yawn....

pretty much shoots down your contention that a simple linear equation describes the distortion for an audio device.

Never said that, Jon.

The problem with the methodology described in this paper and your test signal is that there is no manual way to verify that you are getting reasonably correct results as there are with the current more simple methodologies that have made it through the standards process and withstood the test of time.

-Bruce

[J Risch]

You really don't get it, or are refusing to see the light.

Your comments and claims are on record, and to try and deny them is the silliest thing to attempt. Your claims have been rebutted, and your comments are shown to be a slanted and personal view that has no relationship to reality.

End of any further attempts to explain things to you Bruce, it is futile and not worth the effort.

Jon Risch

[FLZapped]

You really don't get it, or are refusing to see the light.

Your comments and claims are on record, and to try and deny them is the silliest thing to attempt. Your claims have been rebutted, and your comments are shown to be a slanted and personal view that has no relationship to reality.

End of any further attempts to explain things to you Bruce, it is futile and not worth the effort.

Jon Risch

Thank you, because I'm tired of your hand waving and endless twisting of the facts. If you insist on further hand waving, at least shave your armpits. Nowhere have you actually presented a convincing argument or brought forth any relevent facts that conclusively proves your position.

So if you want to come back for more, maybe we can talk about the proof you have for dielectric sound. silver sounding bright, multiple phase reversals in coaxial cable that is less than a tenth of a wavelength, noise in wire, and your completely unproven listening methodology that supports your theories, yet no one else in the world has verified any of your claims with any method, much less yours.

Bogus theories that you have yet to prove....just like you haven't proven any real usefulness for your phiddle-phaddle test signal.

-Bruce