On Fri, 06 Feb 2009 17:51:47 +0000 (GMT), Jim Lesurf
wrote:

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

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.

I'vw wondered about this for two reasons. One being the idea implied in
what you say - that the subwoofers may sometimes also radiate audible
amounts of higher frequencies. The other being that perception of LF
directionality might be strongly dependent on the room acoustic, etc..

I think vestigial HF content may be something to do with it. My sub
empties into the room in the corner behind a sofa, which would
suppress any HF quite nicely.. I chose the corner because that deals
most equitably with room modes - and because that was where the
understairs cupboard I used for an enclosure was.

I find one sub is fine in our living room. But it is a small room, which
makes me wonder if the room reverb might muddle up directional perceptions
at a higher frequency than would be the case in free space or a larger
room. Indeed, I get better directional/imaging behaviour in the hifi room
which is larger. But also more symmetric, so hard to decide what is doing
what! :-)

Reverb or modes? I wonder which is the more important for this.

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