What s behind your chair?

Having been the butt of jokes for last week's "What's in front of your chair?" thread, I will once again stick my neck on the chopping block and start a similar thread.

Right now, I have a cloth covered oriental folding screen against the wall 4 ft behind my seat. It definitely helps with imaging compared to a bare wall. However, I am considering putting my floor to ceiling bookcases behind my listening position filled with records, CDs and books. There is enough variation that it should be a pretty good diffuser.

Does anyone have an opinion as to what works best behind'ya: absorbers or diffusers? With what audio specific products have you had great sound? e.g. RPG skyline. How about DIY Tweaks? Let the games begin.
F. Alton Everest ("Sound Studio Construction on a Budget", "The Master Handbook of Acourstics") and Robert Harley ("The Complete Guide to High-End Audio") seem to agree that on front and back walls, diffusion is best. I put an array of four RPG Skyline diffusors on my back wall, and am extremely pleased with the sound. I have DIY designs for imitations, also for RPG's "Omniffusor", which should work about as well as the Skyline--contact me if you're interested and able to cut Styrofoam accurately into "towers". Your bookshelf is a pretty good potential diffusor already: try varying the depth of the books. It might look odd but sound very nice.
Post removed 
When I put two bookcases (about half-filled), one floor-to-ceiling and one 4 ft high, in the back of my home theater room, sound became richer. Putting tube traps in the front corners got rid of the boominess. The room is only 7' x 11', so I didn't expect a big, rich sound, but I pretty much got it.
I put a rug pad on the wall behind my chair. My friends keep asking why my systemsound so "quiet". I think I know.
Good for you for having the courage to withstand further ridicule. Behind my listening chair, I have many 2 x 4 foot acoustic panels made from Masonite, convoluted packing foam, and acoustically transparent white fabric. These homemade panels were inexpensive, yet they are surprisingly effective. I have experimented many times with and without them under differant listening conditions, but I always put them back.
Out of the extreme jealousy I have for Angela and her husband, I've found the only way I can deal with it is recognizing I have the Pacific Ocean behind my listening position. O.K. is 1600 miles behind, but I'm talking survival here.
I recently put a rug on my back wall, it hangs about 2.5" out from the wall. It made the frequency response in the room nearly perfectly flat, except for a bass problem I am woking on solving now. The rug is about 6'X8', short fibers and fairly light weight. Beneath the rug is a fabric covered couch, with another rug in front of it.

The rug on the back wall made the sound settle down; highs are less harsh, the soundstaging improved significantly, and the whole system just sounds 'calmer' now. Not too laid back, but finally not too aggressive anymore.

Both this thread and your previuos one are excellent subjects, so please do put up with the jokes... I know I mean well when I post em.
....the rug in front of the couch is on the floor, in case you're wondering... :)
meta, if yer wall is only 4' behind ya, i'd suggest absorbers extending at least 3' either side of the *sweet-spot*. if the wall is a bit further back, but still in the vicinity, then i'd go w/diffusors. if ya got lotsa room behind ya (i'm fortunate to have >20'), then i am a follower of the *dead-end/live-end* room set-up, where the walls to the sides of, & behind the speakers are *dead*, ie - w/absorbers & diffusers, and the walls in front of the speakers are *live*. my only mod to this would be to place absorbers at the 1st-reflection-point to the listening position along the side-walls, if they are close to the speakers.

doug s.