Using a curtain of MLV as a "Limp mass" inside a staggered wall - AVS Forum
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post #1 of 9 Old 01-13-2010, 06:33 PM - Thread Starter
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According to this page:

http://www.greengluecompany.com/greenGlue-vs-MLV.php

The best theoretical sound absorption would come from a limp mass barrier (see the appendix).

I'm planning to use green glue+double drywall and decouple the studs with 2x6 footer/header and 2x4 studs. This seems to be the standard setup.

Would hanging a curtain of MLV inside the wall (weaving it between the studs) help absorb sound travelling through the wall. It would be the ideal "limp mass" since it would be a curtain, and I've got access to a bunch of free MLV from a different project.
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post #2 of 9 Old 01-14-2010, 07:03 AM
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Quote:
Originally Posted by snurf View Post

Would hanging a curtain of MLV inside the wall (weaving it between the studs) help absorb sound travelling through the wall. It would be the ideal "limp mass" since it would be a curtain, and I've got access to a bunch of free MLV from a different project.

It adds some mass, which increase medium to high frequency isolation. But you also creating a "triple leaf" wall, which in general makes low frequency resonances worse. Put extra mass on the double leaves, where they belong.

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post #3 of 9 Old 01-14-2010, 07:06 AM
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Quote:
Originally Posted by terry montlick View Post

it adds some mass, which increase medium to high frequency isolation. But you also creating a "triple leaf" wall, which in general makes low frequency resonances worse. Put extra mass on the double leaves, where they belong.

+1

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post #4 of 9 Old 08-23-2012, 07:31 PM
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I had heard that because mlv is a limp mass and gives a little when hung as a curtain as opposed to a rigid barrier, that this would allow the air gaps to still behave as a single air space, negating the triple leaf; is this just theory or bs in general propagated by mlv sellers?

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post #5 of 9 Old 08-24-2012, 06:03 AM
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bs

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post #6 of 9 Old 08-24-2012, 07:37 AM
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Why are we opening up ancient threads?

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post #7 of 9 Old 08-24-2012, 03:42 PM
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relevance; this one of the few relevant posts that came up when I typed in 'mass loaded vinyl'. Beyond the first couple pages, all I got was 'vinyl records'.

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post #8 of 9 Old 08-24-2012, 08:58 PM
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Snurf,

I completed my theater room addition (on the 2nd story) last year and used the same double wall construction method you are using. I did use two layers of mass loaded vinyl on the floor but not in the walls. I separated my double walls by about two inches with double 5/8 drywall on each side with Green glue between the drywall. This makes for a tremendous sound barrier. Really amazing. At reference levels you can hear some sound but it is incredible the damping and sound reduction that is present in my house. It is so good that my wife and I can watch a movie at normal but not reference level and the kids can be playing or watching another movie in the game room next door with no problem.

Not sure what the effect of the mass loaded vinyl in the walls would be. I would space out my walls a bit farther vs trying to use the mass loaded vinyl. I have also used the mass loaded vinyl in an outdoor fence project and it is not easy to work with (due to the weight). Make sure that you seal under the drywall with the acoustic sealant that the Green Glue manufacturer makes.

The weak link for sound passage in my room is the door even though we customized a solid wood external door with mass loaded vinyl and additional wood. A double door system is best.
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post #9 of 9 Old 08-25-2012, 09:55 AM
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Mass is mass, so MLV works but is among the most expensive sources of mass. Often used under carpet if all you have is 1/4" to spare. Otherwise plywood, OSB, and drywall are all more massive choices for much less. Also easier to install. You also then have the option to damp the old and new plywood with a damping compound.

MLV, while itself internally damped, does not appreciably damp the mass that it in contact with, which is a really big deal.

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