#1902815 - 03/03/08 06:04 PM
Armstrong rigid fiberglass + fluffy fiberglass
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muratozer
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Registered: 03/03/08
Posts: 2
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Hi Ethan,
First, thank you very much for teaching us so much about room
acoustical treatment. I learned a lot from this page.
Question for you: As far as I understand from the tables you have
shown, 2 inches thick 3 pcf material is better than 1 in thick 6 pcf
material even at 125 hz. Hence, it sounds like, it is actually the
mass per sq ft of the material which determines low frequency
absorption. Still, a bit looser material with the same pounds per sq
ft will perform better since it will reflect less. Am I right up to
here?
Now, I have found 2x4 ft, 5/8 in thick Armstrong rigid fiberglass
ceiling material. My idea is to peel the plastic coating on it, put
12" (R38) fiberglass on it with paper facing to ceiling material,
finally cover them with burlap, so that the fiberglass is compressed
down to about 6". Then, the traps will be placed at the corners with
fluffy side facing towards the room. I don't expect 5/8" rigid
fiberglass to do a lot (except backing the fluffy stuff), however, I
expect the final product to be at least as good as 2" thick 705. How
do you think?
I ended up with such a cheap design because my room is pretty big
(about 15x30 plus a large kitchen on the side) and I need MANY panels.
Thanks again,
Murat
Note: Above is an e-mail I have sent to Ethan before I knew this forum.
So, of course, everyone is welcome to reply.
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#1903133 - 03/04/08 09:27 AM
Re: Armstrong rigid fiberglass + fluffy fiberglass
[Re: muratozer]
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Ethan Winer
MP Hall of Fame Member
Registered: 06/12/00
Posts: 5300
Loc: New Milford, CT, USA
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Hi Murat,
It's all about the depth of the material. The more "wave that fits" within the material, the more it's absorbed. Your idea to use fluffy fiberglass packed to 6 inches and fronted by ceiling tiles is perfectly valid and will work well.
--Ethan
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#1903425 - 03/04/08 07:40 PM
Re: Armstrong rigid fiberglass + fluffy fiberglass
[Re: Ethan Winer]
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muratozer
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Registered: 03/03/08
Posts: 2
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Thanks a lot Ethan!
Just to make sure about a detail: I was planning to put the thin panel to the back of the fluffy fiberglass, i.e. towards the wall in order to improve high frequency absorption with fluffy layer first. Maybe my poor English: Does "fronted by ceiling tiles" mean the same thing or did you mean the other way around??
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#1903705 - 03/05/08 10:43 AM
Re: Armstrong rigid fiberglass + fluffy fiberglass
[Re: muratozer]
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Ethan Winer
MP Hall of Fame Member
Registered: 06/12/00
Posts: 5300
Loc: New Milford, CT, USA
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I meant the other way around, with the tiles in front to give a nicer smooth flat surface. Or just use fluffy fiberglass. Tiles against the wall won't do anything useful beyond what you'd get from fluffy fiberglass.
--Ethan
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