>(see the fifth post in this thread).
Boris,
Thanks for pointing that out -- guess I should have read all the previous posts first before posting! Thanks for your comments, also.
About multiple subs, I think you're right, using multiple subs helped a lot to smooth out the very low frequencies and to broaden the seating area for good lows. So much so that I would definitely recommend anyone to get two or three cheaper subs rather than one expensive one, no matter how good that one may be. A single sub is going to leave significant response suckouts due to the room and be more seating position dependent, which can't be fixed by improving that one sub.
On one of the other forums, there was a discussion about "Double Bass Arrays", an even more aggressive way to fix the low-frequency room modes problem. I haven't tried it yet, but the idea seems to make a lot of sense, at least to me. To do it, you put several mono subs on the front wall, spaced to prevent lateral variations, and drive them all in mono. Then you put another matching set of subs on the back wall, but drive them in inverted phase and delayed by the time that it takes a sound wave to cross the room. When the wave from the front subs reach the back of the room, the back subs eat up the wave so nothing bounces off or resonates. The setup behaves as if the back of the room is completely open, the side walls don't exist, and the front wall is inifintely large -- the wave from the front speakers just passes through. Takes a lot of subs, though, so that is definitely a diy effort.
I found the link again, if you want check out:
http://www.avsforum.com/avs-vb/archive/index.php/t-837744.html There was also a thread about it last year here on Audio Circle, it turns out:
http://www.audiocircle.com/index.php?topic=20532.0