Any guesses?

Archives of the acoustics mailing list

Any guesses?

Postby archive » Sun Apr 11, 2004 5:16 am

From: "CactusFire (A.S.)" <cactusfire@x??????xxxxx.xxxx
Date: Wed Dec 15, 1999 11:59 pm
Subject: Any guesses?

Does anyone have any thoughts about what the absorption coefficients for
1/2" or 3/8" of plaster over 2 layers of 5/8" drywall might be? I assume
that the plaster is going to reflect more high-end than the drywall, but
will it also reduce the drywall's bass-absorbing properties? What do you
think?

Andy
archive
 
Posts: 4697
Joined: Sun Mar 21, 2004 6:26 am

Postby archive » Sun Apr 11, 2004 5:16 am

From: "Rose, Max" <mrose@x?????xxxx.xxxx
Date: Thu Dec 16, 1999 12:23 am
Subject: RE: Any guesses?

From: "CactusFire (A.S.)" <cactusfire@c...>
Does anyone have any thoughts about what the absorption coefficients
for
1/2" or 3/8" of plaster over 2 layers of 5/8" drywall might be?

If I recall my remodeling days correctly, I'd say 1/2" or 3/8" to be quite
unlikely these days. The reccomended application over blue board is 1/32" to
1/16". You would see a thicker application in pre war construction where
plaster was applied directly to wooden lathe.

Max Rose
Mastering Engineer
Disc Makers/Seattle
mrose@d...
1(800)553-8906 (206)285-2642
archive
 
Posts: 4697
Joined: Sun Mar 21, 2004 6:26 am

Postby archive » Sun Apr 11, 2004 5:16 am

From: "CactusFire (A.S.)" <cactusfire@x??????xxxxx.xxxx
Date: Thu Dec 16, 1999 12:33 am
Subject: Re: Any guesses?

Yes, I should have mentioned, it's not old-style plaster, it's Structolite, a
perlite aggregate gypsum plaster. It's several coats, thickness ranging from
3/8" to 1/2", with a finish texture similar to stucco.

A.
archive
 
Posts: 4697
Joined: Sun Mar 21, 2004 6:26 am

Postby archive » Sun Apr 11, 2004 5:17 am

From: SRF7@x??x.xxx
Date: Fri Dec 17, 1999 1:41 am
Subject: Re: Any guesses?

In a message dated 12/15/99 7:34:58 PM Eastern Standard Time,
cactusfire@c... writes:

<< Yes, I should have mentioned, it's not old-style plaster, it's
Structolite, a
perlite aggregate gypsum plaster. It's several coats, thickness ranging from
3/8" to 1/2", with a finish texture similar to stucco.
>>

How fine grained is it? Considering:

MATERIAL SABINS/Sq FOOT AT (Hz) 125 250 500 1k 2k 4k
Avg.

CINDER BLOCK, UNPAINTED 36 44 31 29 29
25 0.32
CINDER BLOCK, PAINTED 10 5 6 7 9
8 0.08
GYPSUM BOARD, 1/2 INCH 29 10 5 4 7
4 0.10

I would think the number of little holes in the grain (interstices) makes a
big difference on the HF stuff ... enough to perhaps base your judgment of
the probable outcome primarily on this factor taking into account that since
the plaster is on a panel of gyp board and therefore able to vibrate a bit
that there will be some low freq. absorption either way

Scott R. Foster
archive
 
Posts: 4697
Joined: Sun Mar 21, 2004 6:26 am

Postby archive » Sun Apr 11, 2004 5:17 am

From: Dan Nelson <dprimary@x??????xxxxx.xxxx
Date: Fri Dec 17, 1999 2:07 am
Subject: Re: Any guesses?

The bass absorption drops considerably from 1 layer to two layer of drywall
already. I believe it doesn't drop much more as you add more layers so I
think adding a layer of plaster will be about the same. I have a list of
coefficients for building materials in the file area now, that I have
compiled from about 5 sources.

Dan Nelson
archive
 
Posts: 4697
Joined: Sun Mar 21, 2004 6:26 am


Return to 1999 posts

Who is online

Users browsing this forum: No registered users and 1 guest

cron