"Wally" wrote in message


Stewart Pinkerton wrote:

Will the presence or otherwise of bass frequencies affect how the
cable transfers the high frequencies?

No. This *has* been tried experimentally, and even with ten amps of
bass frequency current flowing, no artifact above -140dB could be
observed in treble tones.

So, what sort of artifact was there in the treble tones?

Nothing audible. -140 dB corresponds to one part in ten million. Pinkerton's
point is even with measurements with that incredible level of sensitivity,
there are no artifacts to be seen.

Once upon a time, a well-known expert in audio perception (James Johnson,
then of AT&T labs, now of Microsoft) was asked for an unconditional limit to
audibility, and he said -100 dB.

This would be under absolutely ideal listening conditions, including an
unbelievably quiet room.

100 dB is the unconditional limit, for sure.

With the usual real-world messiness, the 100 dB almost always falls to
something like 60 to 80 dB, and can be as poor as 20 dB.

IOW if a spurious response is 20 dB or less down, you'll probably hear it
regardless. In typical studio or listening room conditions, you might hear
something that is 70 dB down. Under the most ideal conditions imaginable,
something 100 dB just might be audible.

Hearting something 140 dB down is really unimaginable, in real-world terms.

I can measure artifacts up to about 120 dB down, and at that point copper is
still a *perfect* conductor of audio signals, as are most common metals -
brass, aluminum, tin, nickel, gold, silver, lead, steel... However, add a
little surface contamination at the contact point, and all bets are off!