I am starting the layout for my theater. The front screen wall will be 174" wide and the screen will be 120" wide, this leaves 27" on either side of the screen. I plan on also doing this 27" section in AT material. My question is if I should keep the L & R channel within the 120" screen or put them out side the screen in the 27" area. I would think further apart would give you better sound effects, but can you get them too far apart?

I would put them behind the screen. But thats just me, and I haven't set mine up (not even close, hell haven't even demoed the planned room yet).

I'm sure people with more experience will chime in.

The general consensus is that the L/R should be about at the outside edges of you 16x9 footprint presuming you are going for a Scope screen. My screen is 130x55 and this placement strategy works very well. It was a definite improvement when I moved from my BOC with the speakers on the outside of the screen to behind the screen closer together.

If you put the left and right speakers on the outside of the screen, that is an improvement to have some distance from the center channel.

But haven't we created another problem by putting the front L/R too close to the side walls? It seems those front L/R speakers would be projecting a lot of sound off the side walls, instead of straight towards the listener. How big of a problem is this, to have the front right/left close to the side walls?

Make your screen 168" wide and you can have wider set speakers and have them behind the screen! ;)

Putting them outside the screen are with that little space will cause boundary issues in the bottom end through lower mids. I'd keep them behind the screen.

Bryan

Make your screen 168" wide and you can have wider set speakers and have them behind the screen! ;)

Thats a smart man

same screen dimentions I'm going with - I'm putting them behind the screen.