On Fri, 6 Feb 2009 09:30:41 -0800 (PST),
wrote:

On Feb 6, 9:36*am, "Serge Auckland"
wrote:
"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.

David.

That has not been my experience. I ended up with two subs, each sitting
alongside each main, as I couldn't get on with one only. If the sub was
centred between the two loudspeakers, that wasn't too bad, as at least the
extreme bass was mono, but when the sub was to one side, it was most
peculiar.

That's primarily because most subwoofers aren't: they tend to have
substantial output at higher frequencies anyway. The very low
frequency material could well be in mono, but stuff an octave or
two higher could have substantial difference information, and
that can easily find its way through many subwoofers.

That was indeed my own experience until I built my own subwoofer. It
turns over at about 50Hz, and is impossible to localize in the room by
sound.

d
--
Pearce Consulting
http://www.pearce.uk.com