12" sub. I may have to do the crawl again...when I put the sub where I sit and moved around the room I couldn't hear the sub anywhere. I tell ya, i'm all out of sorts right now. I think the volume may have been too low. The carpet's biggest change seems to be just attenuating those lower freqs quite a bit, so it's way out of wack when the higher freqs (right around 80 Hz) come into play.

Steve