Diffusion versus absorption behind speakers?

Thanks Clio. I think your approach is making more sense to me. Leave the front wall alone and treat the corners of the room and possibly side wall first reflection point.

I am using diffusors from Core Audio Designs behind my speakers. The speakers, which are a front radiating cone design, are just 28" from the front wall (measured from the tweeter), due to space limitations. Adding the diffusors behind my speakers increased perceived resolution, added depth to the soundstage, made the speakers less localizable, and enlarged the image sizes.

I also experimented briefly with absorption, but in my setup, the only improvement was increased perceived resolution. Soundstage depth, speaker localizability, and image size either stayed constant or got worse. I'm not sure what the results would have been if my speakers were farther away from the front wall, but I suspect it would have been similar in kind while less in degree.

The Core Audio Designs diffusors are also among the most attractive room treatments I have seen. I have no connection to the company.

Good luck.

One of the pieces of advice I received regarding diffusion is that the larger the room, the more effective it is. Makes sense considering that diffusion works by spreading the sound around.

These are the diffusers I used:

http://www.decware.com/newsite/room.html

There is some good information on acoustics and room treatment from Decware too.

The Core Design diffusers are extremely nice. Wish I had the space to try those out.

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.