[Arny Krueger]

"Serge Auckland" wrote in message
...
"Arny Krueger" wrote in message
...
Snipped


As I recall, that was the origin of the
0.1% distortion desiderata for amplifiers as it was 10x
better than was likely to be audible, and could therefore
be comfortably taken as being completely inaudible under
all circumstances.

Actually, if I get to pick the music, there is a high probability that
nonlinear distortion of 0.1% in the 20-20 KHz range would likely be
objectionable to you, even if you were listening to a good car radio at
70
mph.

This is interesting:- What music would have 0.1% distortion that's
audible?
That's 60dB down on peak, so I would be very surprised to be able to hear
anything 60dB down on programme, especially when correlated to the
programme.

The undistorted music would be composed of instruments that are very rich in
high frequency overtones, such as certain percussion and brass instruments.

The nonlinear distortion would be effective in the top octave of the normal
audio band - 10 KHz and up. This is a range where the nonlinear distortion
of most equipment is increasing because of decreasing open loop gain
(amplifiers) or tracking distortion (LP). Now for a good power amplifier,
this distortion increase might be from 0.005% at 2 KHz to 0.02% at 20 KHz.
Still not a serious issue. For SET amplifiers and LP playback, the
distortion increase might be from a little less than 1% to 5-10% or more.
Potentially a very serious issue.

The relevant psychoacoustic effect makes the ear far less sensitive to the
high frequency overtones than it is to the IM spurious responses which show
up at lower frequencies where the ear is far more sensitive.

Note that the ear is about 20 dB more sensitive in the 2.5 to 5 KHz range
than it is in the 10-20 KHz range. So psychoacoustically, our 0.1 %
nonlinear distortion is perceived as being more like 1% nonlinear
distortion.

I believe that there is little controversy among many of us over the idea
that nonlinear distortion in the 1% range can be reliably detected. This is
particularly true when the spurious responses are aharmonic, which IM is
very likely to be.