Dave,
I have a group of modes overlapping in the 60s and clustering in the low 70s frequency-wise. I know this because I have tried a couple of different speakers in similar positions in the room. Building a bass trap for those frequencies would require a bass trap way too big to be convenient (or sane).
I'm sort of stuck EQing unless I decide to abandon the Home Theater part of the room and get more liberal with speaker placement. I've been looking at some of the analog pro equipment used by Steve Hoffman in his system as potential solutions I could use. I do need something that can both add gain and take gain away from certain frequencies. Luckily, the pro equipment tends to have options that fall right on my problem areas. Rain has some a nice looking options as well, though I might just spend $300 on a Behringer to play around with first (I do like some warmth in the bass region). Also, it would allow me to change things on the fly, for individual recordings.
He will have a very sweet room if he makes it 39' or 31' on that longest room dimension (39' would be best to maintain room volume). I'm jealous of those 11' ceilings... I had to build all the way up to the joists to get 9'. I had steel beams to deal with, and steal support pipes, and a large iron septic output from the house that I had to enclose in a soffit closet. I can't complain though, because my wife let me have the room to do whatever I want to it.
