2. speakers
  3. 1061290632

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 sean

sean
6,231 posts
 
I don't doubt your results at all. The problem is that most people buying subs simply want to tuck them in a corner or somewhere else out of the way and forget about them. As such, the manuals typically state something to the effect of "experiment with placement". Posting the info that you have may help others to experiment and obtain better results than what they currently are. As you mentioned though, you will have to play around with the phase since the arrival times from the sub(s) to your ears may vary drastically from that of the mains. Sean
>

PS... Yes, the difference that you hear is due to the varying loading conditions / nodes present in various locations.
More to discover