lgl`s soundproof HT - Page 6 - Home Theater Forum and Systems - HomeTheaterShack.com

Old 07-10-09, 08:30 AM
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Ted White

Join Date: May 2009
Location: Michigan
Posts: 888
Re: lgl`s soundproof HT

This can be calculated, but it's along the lines of a foor or two of airspace and 6-7 sheets of drywall on each side. Shocking, really

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Old 07-10-09, 08:54 AM
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patchesj

Join Date: Jun 2009
Posts: 372
Re: lgl`s soundproof HT

Quote:
Ted White wrote: View Post
This can be calculated, but it's along the lines of a foor or two of airspace and 6-7 sheets of drywall on each side. Shocking, really
Interesting. Would using MDF, concrete board, or some other high density material be of benefit? I would think that creating a sandwich of materials with varying densities would broaden the absorption properties of the wall.
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Old 07-10-09, 08:59 AM
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Ted White

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Re: lgl`s soundproof HT

Not really. The resonance of the system is defined by the whole system, not the parts. Mass is mass. If well damped, there's no advantage to using dissimilar densities of mass in a leaf.

The LF resonance point calculation looks at:

Decoupled leaves?

Absorption in cavity?

Air cavity depth (which is related to absorption).

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Old 07-10-09, 09:09 AM
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patchesj

Join Date: Jun 2009
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Re: lgl`s soundproof HT

I wonder how much depth lgl has at the rear wall of his room? In my case the rear of the room backs up to a storage area. Creating a high mass floating wall (2x4s with single drywall on both sides filled with some high density material like sand OR 3-4 layers of 1" MDF, not tied to the side walls or ceiling??) in front of a 2' filled cavity (fiberglass or cotton?), with the final isolated double drywall behind that would create this low frequency absorber?
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Old 07-10-09, 09:20 AM
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Ted White

Join Date: May 2009
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Re: lgl`s soundproof HT

Absorber is a term generally used to describe a treatment of sound remaining in the room. The sound we're describing has sufficient energy to enter (and leave) the room.

The object is to build partitions with as low of a resonance point as is practical.

Decouple the framing with a double stud wall.

Have as large a gap as possible between the two frames

Add absorption with standard R13 iberglass.

Add mass, generally double 5/8" drywall

These are the factors that lower that resonance point. Keep in mind that we're only able to significantly affect frequencies at 1.5X the resonance point and up. So if a wall had a resonance point of 60Hz, we're going to start to see a drop in performance at 90Hz and below.

Also your earlier question about a 45 Hz wall would be more along the lines of a 1' air cavity and 3-4 sheets of drywall. That's a guesstimate this morning.

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The Soundproofing Company
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Old 07-10-09, 09:35 AM
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patchesj

Join Date: Jun 2009
Posts: 372
Re: lgl`s soundproof HT

Now that I think about it, trying to absorb frequencies that low would be very difficult. My original concept was to allow a mass in the room to be "moved" by the pressure waves and try to dampen/translate the energy (a tuned mass damper??). And this is why I'm not a professional...
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Old 07-10-09, 09:37 AM
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Ted White

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Re: lgl`s soundproof HT

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Old 07-14-09, 03:47 AM Thread Starter
lgl

Join Date: Aug 2008
Location: norway
Posts: 146
Re: lgl`s soundproof HT

Hello again. Thanks for all the feedback in this thread,
have finally realized that it is not possible to build the room completely soundproof.
Thanks to all the feedback I now know how to build the room.
I will build it as solid as it is possible within the limited space I have, walls and ceiling get 2x 1/2 " drywall and 1x 1/2" MDF and green glue between the layers. I come back with pictures to describe the build
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Old 07-14-09, 07:18 AM
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patchesj

Join Date: Jun 2009
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Re: lgl`s soundproof HT

Looking forward to the pictures!! Good luck and keep us informed. Out of curiosity (maybe I missed it in the thread), why 1/2" drywall, why 1 layer of MDF, and what will the sandwich look like (dry W, dry W, MDF? or MDF in the middle?).

Thanks
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Old 07-15-09, 08:57 AM Thread Starter
lgl

Join Date: Aug 2008
Location: norway
Posts: 146
Re: lgl`s soundproof HT

Quote:
patchesj wrote: View Post
Looking forward to the pictures!! Good luck and keep us informed. Out of curiosity (maybe I missed it in the thread), why 1/2" drywall, why 1 layer of MDF, and what will the sandwich look like (dry W, dry W, MDF? or MDF in the middle?).

Thanks
Hi patshesj. It is drywall/drywall and MDF as the inner wall plate and i`ll use 1/2 " because it is the cheapest solution, 5/8" comes only in fire-plate design.
This is the type of MDF wall plates I`ll use
lgl
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