Why dual subwoofers ?

Lej1447- I use two subs from one dedicated subout and split with a Y from the receiver, as well as a y on each sub cable to input to BOTH r and L inputs to each sub. I stack mine and I have a somewhat small room which enables me to do this. I am still tweaking but can make some brief comments on a much lengthier topic; Stacked subs give me more DB at the lowest extension of the sub. Splitting the signal of course allows a lower gain to be used on each sub for same SPL. Separating the subs can indeed "clean up" the bass, but also can easily reduce the volume.

I have a fair amount of tweaking left to do but I am leaning towards one sub for music and two for HT and I like being able to do that frankly.

I consider the subwoofer to be an integral part of the speaker system, just like the woofer, midrange, and tweeter. The fact that it happens to be in a different enclosure is a detail. Accordingly, I think that each main speaker deserves its own subwoofer, colocated with the main speaker, and driven by the LF signal component of the particular channel (not a mono SW mix). Thus, for my multichannel rig I have three SW (for the fronts) and will some day get around to installing SW for the rears. In my view the main function of the SW is to avoid extreme excursions of the main speaker woofer cone (or planar diaphram) so that the main speaker can do a better job on the upper bass.

Let me second the post by Exertfluffer.

Exertfluffer is absolutely correct - that the use of dual
subwoofers can give you better, smoother bass.

However, that is only true if you know what you are doing during
the setup.

With dual subwoofers, you can get phase cancellation, and
comb filtering - and really create a very peaky and uneven
bass response in your room.

If you understand acoustics - by all means - go with dual
subwoofers.

If you don't understand acoustics - you run the risk of
creating a very poor soundfield in the bass. Setup of a
single subwoofer is far less problematic.

Dr. Gregory Greenman
Physicist