Robert, I've got dual subs running in a two channel set up. First, let me say I've never been a huge fan of trying to integrate a sub into a music only system. Always preferred just the speakers to handle everything. Well, recently I acquired some bookshelf speakers that I love, but they are a bit thin on the bottom end, so I felt a sub was needed.
One of the things I like about these speakers is their wide soundstage. When I added a single sub I got the bottom end, but somehow the width and depth kinda collapsed on me. I bought a long RCA cable and tried multiple different placements and fiddled with the gain, crossover, and phase, but still couldn't get satisfactory results. Went back to listening to the speakers by themselves.
Soon, I came across a deal where I got two matching subs that had what I was looking for in terms of size and hook-up options. My preamp has two sets of outputs. I run one set of outputs to my amps with a 70Hz high pass filter attached. This cuts off all frequencies below 70Hz going to the speakers. This is supposed to ease the load on the amp, but I feel it also cleans up the crossover area where the sub integrates. I am by no means an expert, but this is what my ears tell me. Kinda the reason why I never really like subs with music--always felt the crossover was the weak point.
Anyway, from the second set of outputs on the preamp I run RCAs to the line level inputs on the subs. The subs have both a left and right input. I keep both subs right next to the speakers, but set them so they are assymetrical to each other. I think one of the key things to running dual subs is to have a various phase dial--not a two way switch, but a continously variable dial. I don't have any test equipment, so it took a lot of listening and adjusting to get the subs to work together.
As far as the sound, I much prefer them to a single sub. I not only get more extension, but stll retain the wide soundstage. I have a small room (11.5 x 11.5) and you'd think running two subs would be overwhelming, but it's not. I wasn't looking for lots of vision-blurring bass, but a three dimensional presentation to the music. Something I felt could not be achieved with a single sub. Maybe with a lower crossover you can get away with a single sub with less localization problems. Well, there are probably lots of variables like room size and shape, listening distance and location, sub placement, etc.
Robert, this is just my opinion. Lots of people on the board run one sub and are perfectly happy with it. I'm not trying to say one way is better than the other, just offering my take on it. What JohnK said about listeners not being able to discern a difference in a blind test is interesting. I believe psychoacoustics play a huge part in our interpretation of what we hear, and it is so subjective it is often hard to say what is correct and what is not. Sometimes the best solution is to try something and see for yourself. No harm, no foul.
JohnK, believe me, this is not an underhanded attack on you. You have a lot more knowledge than me on. . .well, just about everything
. Just trying to give Robert my take on dual subs.
