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Discussion Starter #1
Having followed along here and at the AVS forum, I'd come to the conclusion that I'd do the wall behind my AT screen with 2" OC703 and use 2" OC703 for corner bass traps. But, I was going to line the side and back walls with 1" Linacoustic covered by GOM. However, it turns out that the local supplier has 1" OC703 much cheaper than Linacoustic and is suggesting it shouldn't make any difference.

What do you think bpape and others? Should I go with the 1" OC703 or hold out and pay for the Linacoustic?

Your advice is greatly appreciated.

-Mike
 

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1" 703 is fine but you don't want to cover the whole thing. On the rear wall, you'll want thicker and likely with an FSK facing on it to keep the surround field lively but still help with bass control.

Bryan
 

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Discussion Starter #3
Thanks Bryan for the quick reply. You are the best! One of these days I'll get a construction thread going with pics. In the meantime...

1" 703 is fine but you don't want to cover the whole thing.
I'm planning to do a simple, clean look with Fabricmate track and GOM floor-to-celiing. I had a feeling you wouldn't want me to do the insulation behind it the whole way. What should I use for a substrate behind the fabric in the areas that won't have the 1" insulation?

On the rear wall, you'll want thicker and likely with an FSK facing on it to keep the surround field lively but still help with bass control.
In addition to the corner traps behind the screen, I'll have a 12" x12" soffit around the perimeter that I'm planning to stuff with either cotton (from you?) similar to Sandman or fiberglass insulation. With that in mind, do you think I'd be okay with the 1" on the back wall or do you still suggest 2"?

By the way, this is a small room (13' W x 18' L x 8' H), that will have big sound including Klipsch THX Ultra 2 and an IB sub with four 18" drivers.

Thanks again,
Mike
 

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What we're trying to accomplish on the rear wall is to deal with bass cancellations at the seating position. If at all possible, I would do 4" with FSK facing. In the soffits, I would also use some sort of facing if for nothing else than to minimize absorbing too much high end.

Where there is no insulation on the walls, just leave a gap. If you want to have something firm behind there, plywood, MDF, drywall, etc. work just fine.

Bryan
 

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Discussion Starter #6
I'm back with more questions for Bryan :)

So, I modified the back wall furring layout to accept 2" OC703 with FSK. Can I use the same stuff for the corner traps? Or, do I need to also buy OC703 without FSK for the corners?

And, should the 1" OC703 I'm putting on the side walls also have the facing?

Finally, do you still sell the cotton that I would put in my 12" x 12" soffits around the room's perimeter?

The reason I'm asking about the FSK is that my local source for OC703 says its a little nicer to install with the FSK and also I'd like to keep it simple by ordering just two varieties (1" and 2") rather than four (with and without FSK).

Thanks,
Mike
 

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For the corners, it depends on how you're going to do it. If cutting into triangles and stacking, the FSK would be fine in the front corners. We want the front to be fully absorbent.

Side walls definitely not FSK faced (though if you're going to get it faced, all you have to do is put the facing toward the wall instead of facing out into the room).

Honestly though, the FSK faced is a lot more expensive than the unfaced.

GIK does not carry the cotton. Sorry.

Bryan
 

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Discussion Starter #8
When I asked for OC703 I got Knauf. According to the data at Bob Golds, I'll assume it is okay. I bought it all un-faced. Next question...

I've been searching to see how people attach the board to the wall. I see some used 3M Super 77 spray. I saw one guy mentioned dry wall screws and washers. What's the best method?

Thanks,
Mike
 

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Personally, I like to use a few screws with fender washers. Even the plastic washers are fine.

The Knauf should be fine as long as it's the same 3lb/cu ft density.

Bryan
 
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