2 subwoofer???

Virtually all CD's are mono below 80 Hz, so I doubt there would be a significant audible difference between dual mono subs and dual stereo subs.

I do believe that dual subs offer significant room integration advantages over a single sub.

From my investigation of the subject, there seems to be two well thought-out schools of thought on dual subwoofer placement. One holds that the ideal is to place the subwoofers to the extreme left and right of the listening position. This maximizes the interaural time difference and thereby the sense of spaciousness that the subwoofers convey.

The second school of thought recommends what could be described as highly asymmetrical placement, to maximally stagger the path lengths from each sub to the room boundaries and the listening position. This results in the smoothest bass, and is the technique that I use most
often.

Duke

Hi Dbld,

A basic premise of the second school of thought is that room acoustics dominates in the bass region. So the idea is to use what inevitably happens in the room to your advantage as much as possible.

Consider the single subwoofer situation: There's a path length from the subwoofer to your listening position, and then there's another path length from the subwoofer to the opposite wall and back to your listening position. At a certain frequency, the difference between those two path lengths is equal to one-half wavelength. At that frequency you will get cancellation at the listening position. Higher up there will be a frequency where the path length difference is equal to one wavelength, and at that frequency there will be reinforcement at the listening position.

Obviously you have more than one wall in the room so the situation is more complex, but you get the idea. You can get quite large peaks and valleys in the in-room reponse at various locations depending on how the reflection patterns coincide.

Now if you put a second woofer in the room positioned such that its path lengths do not concide with those of the first woofer, the peaks and dips from their outputs will never exactly coincide (in other words, they will be "decorrelated"). So the net result will be a smoothing of the response throughout the room.

Here's an example setup: One subwoofer located near the left front corner but elevated up several feet off the floor, and the other subwoofer along the right wall a little bit behind the listening position but well away from the corner.

There may be a way to mathematically predict optimum locations for randomizing the interaction patterns of multiple subwoofers in a room, but that's out of my league.

Duke

Thanks, Bignerd100.

Giving credit where credit's due, my primary source for the above-mentioned first school of thought is David Griesinger, and my primary source for the second school of thought is Earl Geddes.

Just for the record, Earl recommends having more than two low frequency sources in the room, and preferably a mixture of vented and sealed. So I doubt that he'd have a problem with using two non-identical subwoofers.

Duke