I am looking at upgrading to a projector, and do to limited space I want to have my M22 mains and VP 150 behind the screen. Problem is the screen with extensions will be 12" from the back wall. Does anyone forsee any problems with the M22s port being only a few inches form the rear wall? Should I have some curtain material behind the speaker or bear wall?

Nick is the resident expert at acoustically-transparent stuff. Check out his 4.0 build thread.

My opinion is that a few inches of space behind the speaker is plenty. And I don't think that having sound-absorbing material on the wall behind them could possibly hurt, and it might help.

Have you considered a vertical M22 as a center? I think that's what I might do if I'm ever lucky enough to be in your position.

Congrats on the projector!

Hey. I'll chime in (as if on command)...
I'll make this quick as I am supposed to be watching a movie right now...
Sound absorption behind the speakers is a good thing.
A few inches is fine.
What screen material are you going to use?
Depending on the material, determines how close to the screen material you can place the speakers from the screen material itself. Many work best with at least 4 inches between the screen and the speaker, but I know of some good stuff that actually does OK with the speakers almost right up to the screen.

Let me know what screen material you are going to use, and we can figure that part out, and from there we can see how much room you have for space behind the speaker and the wall and how much space you have for sound absorption material. A curtain may not do as much as you think.

M22's have a rear port. Thinking sound absorbing material behind speaker not a good thing.

I'd go minimum of 3 M60's for best effect. Can always move screen out a couple more inches. Spending other people's money is a lot of fun.

Cat, my m60s have rear ports and I have my entire front wall covered with absorbing material. It works great since you are still reflecting some sound off of the back of the screen and you need to "kill it" before it just keeps bouncing around between the wall and the screen making the sound muddied.

Plus, the absorption is for more of the upper frequencies (except the bass traps, but those aren't right behind the speakers) and the sound coming out of the ports would tend to be more lower frequencies (I know, these are smaller bookshelf sized speakers, and not deep bass producers) and those sounds won't be absorbed by the dampening material.

While your logic seems solid, and until I actually did it, I would have tended to agree with it, but in practice it is OK to put some absorption behind these speakers. Now, LFR speakers would be a different story, but I would not be sure that they would be good for behind a screen wall anyway.