I built some subs a few years back, loosely modelled on the EV TL440(driver compliment is EVX180B). They are 9 cubic foot boxes in black piano lacquer. I've got one in each end of the living room powered by a QSC amp. More than enough bass for this place, I know. They sound fine during movies(lots of thunderous bass for explosions, soundtracks and the like), but when I want to listen to a CD, it seems as though they are lacking in the bottom end(60Hz & 90Hz area) and I have to turn up the gain. There's still plenty of bass, mind you, but it seems as though there is something missing. I'll explain...

I've swept them and find that there is plenty of bottom between 40Hz and 55Hz, then it drops(-2 or -3db) between 55Hz and 65Hz, comes back hard(+3 or +4db) at around 70Hz until 80Hz, then starts to roll off because of the crossover, at 100Hz. I also noticed plenty of cone movement between 30Hz and 37Hz but not much in the way of 'air movement' from the vents. (Nothing below 30Hz as I have anything below that cut with a filter)

I contacted Electrovoice to ask if there was something I could do, but didn't get any help.(I understand, though) One techie I spoke with suggested "they may be peaking to high", and that I cover one of the two vents and shorten the other one to lower the tuning? I haven't tried this because the advice I DID get from someone else, suggested that I should use 2 vents at a minimum of 6" dia.

I don't know, maybe I should just leave well enough alone? I just think there should be more air movement sometimes.

If I do have any questions, comments or dirty jokes, I'll be sure to post them here. Thanx again!

Mark BT