The 40hz bump is the room node and even the subs have it, however audyssey corrects the subs just fine. Problem is the receivers crossover does not have a steep enough roll off to cut these speakers out. With the sub turned off and the crossover set to say 80hz the speakers are still playing down into the 40's. On their own the monitor 7's dip into the low 30's in my room.
I am about 12 feet from the back wall and about 11 ft or so from the speakers. The speakers are about a foot from the wall. I have not tried moving them out from the wall more yet.
You can see the room setup here.
What's happening I think is because the fronts are not rolling off like they should, they are playing information that sub is supposed to be playing and that just exacerbates the problem.
You can adjust the distance settings for the speakers, right? Play with that, at .1 ft resolution. Turn the sub off and set the front speakers' distance so you get the best bass response and image, but don't marry yourself to the actual distance- it's all relative. Do this using music with full-range sound and lots of percussion to give you timing cues. THEN, turn the sub on and work with the setting for that to get the best blend. Use your RTA software to find the flattest response with only the front speakers playing and watch the response dip when you turn the sub on. If the dip is extreme, reverse the polarity of the sub or main speakers. Another thing I would do is move the sub so it's not centered on a wall. Also, I see that you don't have anything
in, or at the corners to absorb energy. I would strongly recommend adding something thicker there- it made a huge difference in my room and I just don't think Gonzo is getting the job done. BTW- my towers' -3dB is at 38Hz from my seating location and the sub crossover in my receiver is set at 60Hz. With the sub on, the -3dB drops to 34Hz. Since it's a smaller room and I don't feel the need to go below this, it works for me. I still want musical realism and I don't listen to pipe organ music but I'm realistic enough to know that the lowest frequencies won't come without a high price. I'm very happy with the sound of bass guitar and all drums on well-recorded music. It's sometimes hard to get these "right", as well as have natural sounding human voices. Having played bass and guitar for a long time, I have a good way to compare the real thing with the simulation.
Changing the distance setting for the sub is like having a variable phase control because you can "virtually" alter the sub's position in .1 ft increments and that's a lot better than just being able to reverse the polarity. If you listen closely, you'll be able to pick out each separate incremental change which is great, but it becomes annoying. Once you find the best settings, look out- you're not going to want to do much more than listen to all of your favorite music. Hitting the spot is a real 'Eureka' moment.
Don't forget- your listening position plays a major role in how the system sounds. Use the Room Mode Calculator to find where the modes coincide and avoid placing the speakers or your seating in those spots.