[jagman]

The null most likely comes from having the IB centered right to left and having the main listening postion centered right to left. Even though there is a significant drop in SPL in the 40's, it's still well above the pink noise level. It could definitely be worse. When I set up the BFD, I'll do several curves. One for center seating for music, one for center seating for movies, one for sitting a foot or so left (and right) of center for when my wife and I watching movies together.