"David Looser" wrote in message
...
"Karl Uppiano" wrote in message
...



Fortunately, long wavelengths and large excursions are mostly in the low
frequencies, which tend to have minimal out of phase characteristics
(which is why subwoofers are practical).


More to the point as far as subwoofers are concerned, the ability of human
hearing to determine the direction of a sound source becomes less
effective as the wavelength lengthen, becoming pretty well non-existent at
frequencies of 50Hz and below. So not only does it not matter if these
frequencies are presented in mono, but it doesn't matter much where the
subwoofer is in relation to the subs either.

But... the physics behind it are related. We don't perceive low frequency
directionality because given the spacing between our ears (as opposed to the
space between our ears) doesn't allow for much phase difference at low
frequencies. Recording setups with widely spaced microphones can produce
artificial phasing artifacts, but it isn't what we normally hear. Blending
to mono at low frequencies for cutting records or driving subwoofers is
relatively benign for all the same reasons.