Jax2, can you tell me what your main speakers are? That might help me come up with suggestions.
One possibility is to rotate the speaker-listener-speaker triangle perhaps 15 or 20 degrees clockwise or counter-clockwise, as seen from above. This will introduce asymmetry in the horizontal plane, and may reduce the depth of the 80 Hz dip.
What happens to the 80 Hz dip when doors are left open or closed? An open door can be a very effective bass trap, for better or for worse. Does the room have a closet? Try that as well.
I couldn't tell you why Earl favors white noise over pink noise; the latter is what I'd be inclined to use but Earl is one very, very smart guy so he probably has a good reason.
Hey Duke, thanks for the response. It doesn't matter which speakers I use, the suckout always seems to occur at the same point. Looking at in-room response curves the dip is there whether full-range or monitor or? No closets. One single door, and I WILL try closing it and see what happens when I next have a chance. It is immediately next to my right speaker and I usually leave it open with diffusors in front of the open door (first reflection point). The opposite side first reflection has no wall at all. The triangle-rotation is a great suggestion, but WAF prevents that option without major domestic disruption.
Thanks, Duke!

