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On 3 Jan 2004 19:46:42 GMT, (Michael Squires)
wrote:

In article ,
Stewart Pinkerton wrote:
On Sun, 28 Dec 2003 20:29:21 GMT, (Ben
Hoadley) wrote:

"Karl Uppiano" wrote in message
...
"Ben Hoadley" wrote in message
...

[snip]
I did have it demonstrated to me once. you get a analog tone
generator. set a sine wave to 15khz then switch it to triangle wave.
you gan clearly hear the change even though the first harmonic
difference is at 30khz. I don't know if this is a good demonstration
though since its more the distortion within the signal that is the
problem with cd
This can be a misleading demonstration. Switching between sine and triangle
(or sine and square) is only valid if the fundamental tone is *exactly* the
same in all cases. Setting equal RMS values using a meter, or equal peak
values using an oscilloscope will both give erroneous results.

You can *not* hear any difference when the fundamental tone is higher
than 8kHz or so, providing that the level of the *fundamental* is
matched. This is also true of a square wave, which has even higher
velues of harmonic content than a triangle wave.

This is assuming that the amplifier handles frequencies above 20Khz
properly, which a lot of solid state designs ca 1975 didn't. I
assume that at this point a LP filter at the input is standard, but
wouldn't be surprised to find middle-brow equipment which assumes
that the input is from a device that doesn't have output above 20Khz.

Yes, I am assuming that the amp does not produce any IMD products
which image into the audible baseband. This debate was supposed to be
about the audibility of tones above 22kHz, not baseband distortion
products!

(A number of preamps ca 1975 had very high IM distortion at frequencies
over 20Khz, and the IM products in the audible range were quite audible
when the preamp was driven by inputs with a lot of energy over 20Khz.
There are a lot of moving magnet and moving coil designs which produce
a lot of (distortion) energy above 20Khz.)

Hence my concern about the very high levels of wideband ultrasonic
hash delivered by SACD.

I'm not disagreeing with your point, but since I am constrained by a finite
budget I had to choose between imperfect alternatives. I'm quite certain
I heard sonic differences between preamps and amps ca 1975, but every
time I put the equipment on the bench I found a measurable difference.

Agreed. There is no mystery about audible differences among
amplifiers, IME this *always* shows up as a very easily measured
defect.
--

Stewart Pinkerton | Music is Art - Audio is Engineering

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