Where to start?...

Gotta agree with Soundhound regarding playing with two subs and seeing (err...hearing) if there's a difference. Personally I don't notice any "stereo" sub effect, but I'm sure others have since they swear by it. As I tried to say, I think that going from one to two subs is a big improvement not because of a stereo effect, but because two subs (properly placed of course) tends to smooth out the local peaks and dips. Additional subs give additional improvement but the old law of diminishing returns starts to kick in really heavy by the time you get to four. From what I recall of the Harmon paper, there's also the potential of some trade off with extreme bass extension with multiple subs as well - but I'd have to re-read it to be sure. All I know is that when I read it, and looked at my main home theatre's set-up, that I set my goal at four subs. One to go!

But back to the question of impact etc. and big vs small...

When I used to run dual subs and had an ICBM in the loop, I would play with the ICBM's crossover points. Starting at bypass I'd roll off the full range speakers and let the subs handle more and more of the load. It's hard to keep all else equal (like invidual volume levels) but I would pause after each step and recalibrate the levels for all speakers - including the subs. The sound definitely changed. Thinner? Somewhat. Louder? Not in absolute terms since I was recalibrating but yes there was obviously less bass coming from the full range speakers and more from the sub - but of course that's what you would expect. More or less distortion? Nothing noticeable. Was I hitting any crossover points that threw things out of whack? None that I could tell. More impact? Yes. Explosions like in the U-571 depth charge sequence were (and are) much more like external cardiac compression with the full range speakers running full range. You were "hit" from multiple points - rather than from just two. Perhaps that's the answer. There was even less cancellation and smoother response with all running full range. Maybe it's because my full range arrays are fed plenty of power, are relatively high efficiency, and are capable of considerable peak output.

Unfortunately I could probably go on at length - and Monday Night Football is about to begin.

I hope if not confused the issue too much.

Regards,

Jeff Mackwood