quick soffit construction clarification

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CollinStore
Posts: 15
Joined: Tue Jun 08, 2004 11:41 pm
Location: Portland, OR

quick soffit construction clarification

Post by CollinStore »

I have a question about the "lower" divider which supports the speaker box in the attached diagrams. The one which is labeled as being made from 5/8" plywood.

It appears that this plywood sits on a frame attached to the existing outer wall on one end and the new soffit wall on the other. Is this correct? Wouldn't that acousticaly couple the two walls?

Also I see a similar frame directly above the speaker box. Is there a plywood divider attached to that frames as well? Or Is that entire area behind and above the speaker box meant to be open but filled loosely with insulation? Is that frame simply to hold the speaker box in place?

Thanks in advance. I've been searching old posts and haven't found specific answers to those questions.

Collin
CollinStore
Posts: 15
Joined: Tue Jun 08, 2004 11:41 pm
Location: Portland, OR

one more question, kinda

Post by CollinStore »

Sorry about the double-post... but I figured while i was asking questions....

The image attached below is my proposed control room design. It was suggested to me that the wall between the speakers (which i need to built out from the existing wall and at an angle) should be a slot resonator. Does the area behind that slot resonator need to be sealed from the cavity created by the angled soffit walls? Or is this whole area behind the resonator and soffit walls going to act as a giant bass trap?

thanks again in advance!

-Collin
etflutes
Posts: 14
Joined: Fri Feb 02, 2007 3:38 pm
Location: Northern California, USA

Post by etflutes »

I'd like to second the above question--I'm doing exactly the same thing right now.

Collin, my room design is totally similar to yours. I made the wall that is in between the soffits into a slot resonator (sealed from the soffit cavities).

However, after finishing my soffits and installing my speakers, I noticed some boomy/boxy sort of sounds. I then had a low frequency shelf filter made to reduce the exaggerated bass of my flush mounted speakers, and that helped a lot. But the boxiness could still be perceived and it became apparent that my speakers were coupled to the front baffle of the soffit, making it into a big resonator.

I followed the same soffit design plan that you showed above, and the shelf upon which the speaker sits was screwed to the same framework that the baffle was mounted to, so even though my speakers themselves were not touching the baffle, the shelf was.

So just today I took apart the front of my soffits to get at the "guts" and am redesigning them. They will still have a shelf for the speaker to sit on, but it will be self supporting (and attached to the wall behind the soffit), but not connected in any way to the front frame of the soffit. I'll tell you how it works out.

Nonetheless, I'd love to hear some other opinions on your original post.

Geoffrey
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