On Wed, 17 Nov 2004 23:35:44 +0000, Ian Molton wrote:

snip

mick - if you wish to continue discussing this Im happy to respond to you.

Cheers, Ian.

This is all just playing with ideas. I don't profess to be an expert on
hearing, recording or amplification or anything remotely connected with
them! Somebody, somewhere *must* have written books on this stuff, but I
probably wouldn't understand them... grin

I can see where you are coming from: "If listening to a live performance,
for the sake of argument, from a point source instrument, our 'inherent
distortion' is the only thing impacting on the signal."

But our ears don't perceive an instrument as a point source. We hear
positional information - possibly phase and/or frequency shift sensing -
which must include reflected sound and, possibly, THD inherrent in any
frequency shift detection. There are no point source sounds that we can
detect in isolation - except maybe in an anechoical chamber!

Even stereo point sources with perfect reproduction *may* be insufficient
to reproduce all the necessary information as much of it must be at very
low level (where it could be detectable with logarithmic hearing but not
with linear amplification - the source information would be lost at the
microphone).

"If we now make a recording of the signal, again, for the sake of argument,
with a perfect microphone, and played it back from a single speaker in
place of the musician, with a perfect speaker, we should expect the
speaker to produce the same waveform as the musical instrument."

You are quite right - providing that the listener is comparing a point
source live instrument to an isolated single driver speaker in an anechoic
chamber. Another perfect microphone at the original listener's location
should give an exact copy of the source (although if you used a human
listener he/she should only have one ear, with the outer bit (pinnae? not
sure...) cut off!).

In real life we would be producing a point-source representation of the
original, with all the location information stripped from it. It would
measure perfectly, but information would be missing. It would be analagous
to a painting, which is a 2D represdentation of a 3D space.

"If we can agree on the above, this suggests that in order to hear
something that is true to the original sound, we need to have distortion
free reproduction."

IMHO that doesn't necessarily follow. Unless you can be sure of recreating
*all* reflected sound from the original source's surroundings the
infinitely low distortion of a perfect reproduction system will still be
missing information.

I just have a hunch that the THD produced by a valve amp is doing more
than just giving a "warm" and "easy" feeling to the sound. I am wondering
if it is fooling the ear/brain combination in some way. That deception is
translated by some people into a feeling that the sound is more lifelike,
giving rise to their almost unanimous descriptions. This could be going
further than simple addition of even harmonics being used to "fill out"
musical sound to make it feel "bigger".

I don't know. Someone must have done, or be doing, research on this.

--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info
Web: http://projectedsound.tk