Jon Risch distortion test signal

[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