Diffusion versus absorption behind speakers?

Dracule1,

Even if you actually provided information on the size, shape, construction, furnishings, etc. of your particular room, it would be quite hard to guess what would work for you. This is mostly a trial and error process. I've heard numerous rooms designed by acoustic experts and they all sound very different and vary greatly in the amount of improvement achieved.

As for treatment of the front of the room, I agree with those that, aside from corner bass traps, most other treatments give equivocal results. The best "treatment" tends to be moving the speakers as far out from the back of the room and the corners as is practical.

I use, and like, ASC tube traps in the corners of a room. I use double stacks of 16" diameter traps. The bigger the traps, the lower the frequency that they remain effective at controlling the bass response.

A friend of mine in the home theater/audio business has had good success treating the side walls of rooms with absorption/diffusion panels and with corner bass traps from the following company:

http://www.kineticshometheater.com/index.html

Their treatment looks really good too. Also, they don't take up a lot of room in terms of being really thick.

The following source also make a variety of diffusion and absorption products that work well for dedicated listening rooms and home theaters:

http://www.rpginc.com/

I hope some of these have something that might work for you.

I would consult with GIK on this. I think that wall should be third on your list behind bass traps on corners, ceiling etc, then high frequency absorption at the side wall reflections. But get some advice from the pros at GIK and Real Traps too.

Generally, if you don't have dipoles, then things like quadratric diffusers would go on the wall behind your head if your listening position is far enough away from that wall.

Using tube traps requires extreme patience. I have had them since 1988, and having the seams pointed towards the speakers will usually yield quite good results. HOWEVER, the seams will sometimes need to be slightly oblique and they must be moved in 1/64" increments (or less). Additionally, you must move them along the walls -- both sides and rear -- in miniscule increments, so small you can carely tell you moved them.
On side walls behind the speakers, Moncrieff suggested orienting the seams towards the speakers. Forward of the speakers, he suggested pointing the seams towards the speakers. This must be done over a period of weeks. One should move them one at a time. I have around 40 or so, stacked floor to ceiling. If you have jogs in the room, you MUST have traps in those jogs, or the upper bass/lower midrange will sound thickened. When I had an addition built onto the house, there was a jog, so the room narrowed from 13' to 12'8" and I heard the thickening, but it wasn't until a couple of years ago -- 5 years AFTER the addition -- that I looked at the jog and thought, "Hmmm...sound COULD be building up there, too." I put 2 traps in there (8' height) and the thickness disappeared.
It is crucial you move them exceedingly small increments in whatever direction you move them. Forget 1/8" as "exceedingly small." I mean small enough that you can barely see that you moved them. Tiresome? Yes. But the amount of spatial detail, low level detail, transient info, room size, image focus and an actual sense of how instruments sound in a real room will leave no doubt. You must also, when you think you have them moved in exactly the right spot, then move them BACKWARDS a tiny fraction. You will either find high frequency (i.e., bells, triangles, harp) transients better or worse. At that point, either move them back to where they were or leave them.
Seamson traps directly to the side of you are generally best (on cones) pointed at 45 degree angles INTO the room, but again, they require extremely small turns.
I also have the ASC's room damp setup with resilient channels. In this setup, no walls touch each other, not even on the floor, so there is no connection. An adhesive is used to seal cracks between foor and side walls and ceilings.
There's an article on ASC's site by Moncrieff back in 1989.

Hello ,
I prefer to absorb than to diffuse behind the speakers and to use diffusers behind the listening position.

regards,