Jon Risch distortion test signal

[J Risch]

Having little interest in the topic overall, I did not read your preprint.

That begs the question: why so many questions now? At least yours make some sense.

You really should read the paper, I have the text at:
http://www.geocities.com/jonrisch/PhiSpectral1.htm
be sure to click all three pages worth.

1.. Did you correlate standard tests against yours?

I did to a limited extent, using primarily loudspeakers, plotting 2nd and 3rd harmonic against the Phi Spectrals. I had two comparisions in my paper, but one of the graphics got left out (I handed out the mising sheet at the convention for those who attended)

2.. Did you do this using resistive loads or reactive loads, and to what power levels.

Real loudspeakers. If you meant for power amps, I did not do extensive testing of power amps as a separate category, but since the paper, I have measured a few more, and the big thing is, doing so at different power levels.

3.. Did you show distortion products that rise above accepted jnd's which otherwise did not?

I did show distortion levels that exceeded the simple IM or classic HD plots by 10-12 dB, however, some folks would have argued that some of the HD levels were already above audibility, however, I was able to show that a speaker tha measured "OK" by HD metrics, measured much worse using the Phi Spectrals, while another speaker that measured similarly to the first one on HD, remained low on the Phi Spectral. This was one of my points of evidence for the superior resolving power of the Phi Spectral.

Why has industry not adopted a test methodology that you claim is better?

The industry is all over the map, the current simple and limited measurements we have today evolved over a period of many years, and it took years and years for the industry to agree on some of those standards. I do believe that it took almost 10 years for the SMPTE IM standard to be offically adopted, and look how simple that is!

I can say that Klipsch and Cerwin-Vega are using it, or have used it at one time, there may be more than that, most folks would NOT advertise they were using such a powerful tool, if they felt that by keeping under the radar, they would keep other folks from noticing and using it too.

Does your current employer, Peavey, use it? After all, you submitted it under their auspices..and I assume, they paid for it..
Or, are you alone in your beliefs.

I can't really comment on that specifically, suffice it to say, that we could not have developed a 4" format compression driver to have distortion as low or lower than a TAD driver, at about 1/4 the cost, just by accident.
I can also say that I work with many groups within Peavey, including the power amp folks, the guitar folks, and even at times, the digital engineering guys. I can not go any further than that.

BTW, ALL of the time I spent on developing and researching the Phi Spectral was on my own time, after hours or at home. I even paid my own way to the AES convention, which is another story, and one I am also not at liberty to discuss.

For the future:
I have been working with some folks on a super version of this, one that will be wholly integrated into a computer controlled environment, so that much of the analysis would be automated and made easy to view and interpret, as well as a VERY neat twist that will make it even more powerful and relevant to measuring audio devices! This may take a bit of time though, as we are talking about some other guys working in THEIR spare time.
Should be a very interesting end result, if we can get it to do what I think it can.

Jon Risch