Asymmetrical Room Treatment

Chisar, while the foam based devices/absorbers are not as "good", assuming they have a shaped face, you may find the following somewhat helpful for the wall behind you.

Glue a strip of very thin plywood (even just a veneer board) to the top of the foam's back. Get a suction cup clamp with hook (ie. Lowes, HD, Michaels) and stick this to the top of the window behind you. Since the foam is so light, even with the strip of wood, you can hang it directly on the window. Easy to remove when guests come over. I do this as my side window is a 1st reflection point and it is much more productive than just drapes (but not as good as a full fledged absorber).

While there is limited absorbption in doing so, assuming again that it has pyramids or something on its face, it will also act as a diffusor.

Another thing to consider for the open doorway is to use a tension based curtain/shower rod and install drapes in the doorway. With the right material and lots of folds in it even in the closed position, this will provide some support to what you are seeking to balance the two sides.

I recognize that there are better solutions, but based on limitations of renting, higher costs, etc. . . mine are only intended to offer easily changeable, relatively cheap and not to require drilling - as opposed to being the perfect solution that allows us to ignore these restrictions.

I think Kevin has some very good answers, though I am not sure if the OP can take advantage of all of them due to his restrictions in renting.

My question is regarding a 4" diameter (I am assuming it round) or is it a panel type? If its round, doesn't the 4" diameter preclude it from acting as a bass trap? I was under the impression that for the round tubes, one need really about 16" to get into the bass notes?

FYI - I spent my evening installing some new Real Traps - Corners panels (mondos), a couple of PFZ (?) on the ceiling (suspctd about 4"). On one wall, left, I have four 2 X 2 X 4" thick Real Trap Panel sound panels (tilted, out 6" at the top and flush at the bottom) in a 2 X 2 pattern with 2" between each panel. On the opposite side where my window is, I glued laminate thickness playwood onto the auralux backing. They are 4 feet tall, 2 feet wide and 2" thick. The window is about 3 feet tall by about 5 feet wide. I basically bent the laminate so that panels are wedged between the top and bottom window framing - bowing outwards.

My back wall (behind me) is about 15 feet behind where I sit and am justing letting the physical aspects of what behind me defuse the sound (I have nothing specifically addressing the soundwaves behind me due to the distances involved and it doesn't sound like I need anything).

Finally, I have two of the auralex panels between the speakers (in front of the fireplace opening, positioned at about a 15 degree angle - with a point in the center).

I need to put some decent heavier drapes up over the window and auralex bowed panels, but already the room is sounding much better.

Bass is much tighter and I can play a much high SPLs without the sound breaking up, conjecting and just becoming over energized.

Anybody want to make any additional comments it would be fine. I think I need still some corner (wall/wall/ceiling triangles and possible raise higher my front wall corner traps which are pretty wide frequency ranging).