For a single 12 inches non-horn loaded playing below 80 Hz, I'll bet it
would not change a thing.

How much? Go to your venue and turn your subs around then. Or hell just walk
into the front of the sub then to the rear and you tell me if there is a
difference or not.

Actually, if there is some wall behind the
speaker, you may notice an increased output.

Perhaps, but you would most likely end up with some very odd delay times on the
subs.

However, a stack of 18 inches playing to, say, 120 Hz

You cross over 18s at 120?!?! Seems a little high for SUBwoofers. Let your
midbass speakers take care of that.

would be quite
different because the mutual coupling of multiple drivers would cause
some directivity in the higher bass

What does the multiple drivers have to do with it? But nonetheless you shouldnt
have higher bass in your subwoofers.

Meyer went to great lenght to design a "cardioid" sub and the thing have
4 drivers, weight 400 lbs, need extensive on-board processing and huge
power to run. It's certainly not commonplace yet.

Heard both of them, the PSW-6 and the M3D Sub. They are great. You walk onstage
and you cant hear it, definantly takes care of some of the stage rumble. And
they are definantly directional.
I am not saying other subs are not but their output between the front and back
is definantly different.

If you know of a single 12, 15 or 18 inches pro sub that have some
directivity below 80 Hz, please post references.


Meyer 650-P. There is a 6dB loss off axis. That is a signifigant difference in
any world but especially the world or PRO sound.
Almost any line array sub, DVDOSC, X-Line, M3Ds, 760 line array. The Yorkville
PS18. All of them have atleast a 6db loss at the rear.

Subs are omnidirectional somewhat, they are in the sense that Mid/Highs are
not. But even alot of subs are not truly omnidirectional, some can cover
360degrees horiz. BUT only 180 vertical at best. Look at Meyers site they or
EAW have those specs published.

Les