Absobtion on front wall and diffusion on back or vice versa?

[Soits]

Oops, I meant Absorption

Getting confused here so i'm looking for some advice. Many different, reputable sites have conflicting info regaring the placement of Absorption vs. Diffusion on a control room front wall(behind speakers). I've placed some Auralex absorbtion squares on the left and right walls halfway between the speakers and my listening position as well as 2 bass traps on each of the front wall corners. Also, if it's helpfull to know I have 5'x3' window on the front wall facing the control room. The back wall is somewhat u shaped.

Thank you for any advice or opinions

[Ed Belknap]

If there *is* a rule of thumb (and there really isn't -- or rather, for everyone who claims there is, there's an equally reputable source who will refute it) it's that you want the front of the room (where the speakers are) absorptive and the rear of the room (behind the listener) diffusive.

But...

Unless the room is pretty large you may find diffusion is totally unnecessary.

...or unless the rear of the room is U shaped.

Seriously. You've got a U-shaped back wall? Can you say "parabolic reflector"? You absolutely *must* do something to scatter the reflections off that U-shaped back wall, and a healthy smattering of diffusors is just the ticket.

Depending on how large your room is and how "live" the existing surfaces are, you might only need to put absorption on the first reflection points. Do that first, then listen/measure to see if any more of the front of the room requires additional absorption.

[dpd]

What you are after is the reduction of 'early reflections' getting to your ears when the direct sound arrives. Conversations I have had with some very well-known studio designers/acousticians tell me to treat the '1st reflections' (those off the side walls, ceiling, and if needed, the floor, first.

Diffusion on the rear wall ('rear' being behind the listening location') is nearly a given in about any modern studio I have seen. Diffusion, probably more than absorption, is the better course of action - you want to smooth out the 'hot spots' from reflections. Too much foam will kill the reflections, but will also over-deaden the room (a problem I am attempting to fix in my own listening room by removing foam and replacing with diffusors).

Then, there's the ugly problem of bass response...

LOTS to read about this subject all over the 'net. Whole forums dedicated to this.

[Soits]

... quite Hellish on that back wall, probably due to the shape and material(cinder block) and maybe the 10 foot ceilings as well. The bass is fairly tight in the room thanks to the bass traps but i'll definately start moving some Diffussors into the room.

Any thoughts regarding placement (back wall OR ceiling)