acoustically speaking, could a soffit produce any benefits if built like this??

basically I want the side walls of my theater to be smooth (no columns or soffits if I can get away with it).

http://farm3.static.flickr.com/2283/2378003628_de2fb48e18.jpg

That's just a soffit in another room. ;) If you can keep your room free of HVAC and plumbing penatrations by moving into another space, go for it.

maybe this picture will help kinda describe what im thinking.... of course it would go around all walls (minus screen)

http://farm3.static.flickr.com/2024/2378169670_afc5fe918a_o.jpg

so basically since I have reversed columns, I have extra space between what would be a concrete poured cave, I could then use the extra space for the soffits and stuff them full of the correct products. This would then let me keep my walls smooth with no jut outs.

the side and rear columns would hold the subs (1 per wall) and then the side ones would also hold the surround speakers. Then the back wall has two window type boxes that would hold the surround backs.

I guess I'm not sure what your sketchup is showing. Is the right side your HT? Are you making a hollow in a wall? Are you making the hollow to be decorative, or are you trying to make a bass trap in the wall?

If you are looking for bass trapping, my only suggestion would be to move it all the way up to be as flush to the ceiling as possible.

(Cross posted with the previous picture)

Ok, I get it now. You are trying to make alcoves in your walls to hold your speakers? I was steered very hard away from that by this group last year. If you want speakers in the walls, you need to get speakers specifically made for it (with no baffle step compensation, essentially with a crossover network designed for in-wall speakers). You don't want to put any speakers into small alcoves if you can avoid it.

Looks like you will be "wasting" a lot of floor space between the room walls and the outer walls. Not sure what the value of your house is, but you may want to think about the square footage lost as lost value on the home.

yes for basstrap purposes is what Im thinking.... doing the soffit like this, would it do any good (just talking about the soffits right now)? As for the alcoves (or as I like, reverse columns :D) the speakers I am looking at are the Ascend Acoustic 340's for the LCR and Surrounds and the 170s for the surround backs... I thought there might be some sound wave boundary issues(i just made that term up), so I figured 24" wide for a 7.5" wide speaker might be enough... and then for down below for the subs, I figured the problem wouldnt matter that much as its kind of like sticking them in a corner... kinda but not really.

The house isnt built yet. (nor is the land bought). But Im designing the basement around the theater so the footage is not a concern to me. The design above is finished 13'x~25'x~9' or 21.5 from the screen wall to the back wall. (the ceilings are actually 10' but I know I'll need beams and hvac etc.

and while Im at it, im changing the title of the thread i guess lol -- err how do I do that exactly?