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Subwoofers, and standing waves...

I've noticed that placing my Servo-15 at the side of the room (facing the back of the room) produces a smoother room response than placing it conventionally between the my main speakers.
I believe this is due to my main speakers(B&W CDM9NT) reinforcing a different set of room nodes than the subwoofer.
ie: at the side of the room, the sub is within the "anti-node" of the mains at the front of the room, and therefore does not excite the same set of standing waves as the mains.

The difference is fairly significant:
With mains and sub at the front of the room, there is a 6db peak at 40hz and 80hz, and 6db nulls at 60hz and 30hz.
(+/- 12db variation and a rolloff below 40hz)
With the sub at the side of the room(with the phase set to 30 degrees), the peak at 40hz is reduced to 3db, and spreads downward to 25hz, and the 80hz peak is eliminated.
The 60hz null is reduced to 3db, and the deep bass below 40hz is essentially flat to 20hz.
The character of the bass response is dramatically improved, with no subwoofer localization or bottom end thumping.

I'm amazed that this is not mentioned in the manual, or considered an axiom for subwoofer placement.

Cheers
snickelfritz

Showing 1 response by snickelfritz

snickelfritz OP
42 posts
 
The sub is actually along the sidewall, halfway between the listener and the mains, forming a "+" configuration.
The subwoofer driver is facing the back of the room.
ie: the sub is sitting "sideways" against the sidewall, with the driver being equidistant from the sidewall and floor boundaries.

BTW, I tried corner placement as well, with results similar to placement bewteen the mains, except that the 40hz peak was much larger(+6db or so), the rolloff below more pronounced, and the trough centered at 60hz much larger.
Very tubby sounding, with little impact in the midbass.
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