Mike
Try to spend some time getting the acoustic software to work. I will gladly help you if you want it. It is not hard at all. It will enable you to see what is going on, not only in frequency response but in the time domain too. You will be able to move speakers and treatment and instantly know whether it helped your specific problem or not. No wasting time with subjective judgement. Bass guitar's lowest note is E=40Hz. So you might be missing a null that is a higher harmonic. Most bass will be in the octace from 40-80Hz with overtones above that. There is no bass tones below 40, only organ (20Hz - rare) and a half octave of piano. You have to see the freq sweep to know what you're dealing with.
The guy you mentioned who makes bass traps probably can scan the room for you with a handheld analyzer, but maybe not for free?
If you have a subwoofer from HT rig, even cheapo, you can use it to map the bass in the room easier than moving speakers around. You can put the sub at your known listening position (even on the seat) and measure potential speaker spots for flatness. You can also locate good spots for bass trapping by placing sub in one corner with analysis mic in far opposite corner (ceiling even better), move traps for best flatness.
It sounds silly, but make sure you are getting a flat signal out of the speakers. With all that trapping, your bass should be coming through clearly, unless gear is not making it. Take your SPL readings up close to the bass drivers to make sure your getting what you think you're getting. I have a mp3 of Ethan Winer's 1Hz per second sweep that you can use with SPL meter to watch speaker response. If you jam the meter in low range up close to the driver you will reduce room effect by a large margin. At least you will learn something. Let me know if you want the mp3.
I found that leaning the 6" thick 2x4 panels (mondo) on the floor against the sidewalls with the end starting at the speaker line and moving out into the room was a great place to trap bass without affecting soundstaging at all. I am allergic to any absorbtion behind the speakers, except 8th nerve, which is reflective on the front.
Try some more radical experiments to get a better understanding of the problem. Put the speakers deep into the corners of the room, with and without absorbtion in there. You should get a lot of bass reinforcement from the corners. You'll also get problems, I know, but this will tell you something, and maybe show you how placement can help a little. If it helps, you can absorb or diffuse reflections behind them if you have to. Also try out in the middle of the room, close side by side, at say 1/3 length while you listen at 2/3s. These are ideal theoretical distances for minimizing bass nodes at least on the length dimension. Move them around without any preconceived notions of what is right and wrong and see what you can learn. Try the long wall as front.
At this point you have tried a lot of things and not getting traction. Now let your hair down and see what your imagination come up with for experiments! If you desire it this badly, then the answers are within you. Report what you find and Mike or Bryan can help interpret it. Pretend it is a fun hobby for just another couple days before you start throwing equipment out into the front yard!
Sorry it is being so difficult Mike. I hope you get it figured out soon. Let me know if you want the file or some help with the software.
Rich
