MBM/s should help the 50-60hz null. Try putting your 3 3 in the front middle of the wall if possible to see what that does.
You say "having it fire against the back wall, is a lot smoother but there is basically a dead zone from 80-100hz" If your AVR is xo at 60hz or 80hz I would expect to see this. I had a bad null at 160hz (AVR xo at 120hz) and by moving out from center by 1 foot my Right main I was able to raise that null quite it bit. That was the side of the front wall that has the highest ceiling height.
Sorry, thats all I can offer. If you are persitant you should be able to get close. Measure, move, measure, change xo on avr, measure, change xo on sub, measure and repeat until you find what you like. It is time consuming and at times frustrating but in the end it worked for me and did not have to buy room treatments or external eq.
Having the 3 3 and 2 MBMs allowed me to more percisely make changes and see effects depending on the frequency range I had problems.
I had a pretty high peak from 60-100hz, lowering the gain on the MBMs tamed that.
Originally Posted by jesyjames
Thanks for the reply. I have it running in max extension, c/o at 80hz. Regardless of location it seems pretty flat from 15-21 hz or so. I did try both corners on the front of the room. Unfortunately the front corner where the ceiling is at it's lowest is the absolute worst spot. That is the one with the absolutely huge peak running from about 20-40hz, and then the monster null at 50-60. The other corner isn't as bad for the peak, but there is still that huge null. What's weird is I have tried moving the couch backwards and forwards a couple of feet and I can't seem to escape that darned null.