#1917467 - 03/27/08 10:22 PM
Treatment for music venue
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nee
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Registered: 03/27/08
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Greetings! We are investigating treatment to improve the sound of a live rock music venue.
The room is approx 11m wide x 28m long, with a fairly low ceiling - about the same as a suburban house. The walls are concrete block. The floor is concrete, with about 50% covered with carpet. The ceiling is hardboard.
As you can no doubt imagine, the sound - even with a high-quality PA system - is very noisy and boomy, with low speech intelligibility.
We have done a lot of research on this and other sites, but with such a large expanse of wall (and corners!) we are not really in a position to be building large numbers - 100s?! - of bass traps! We would like to investigate the most economical methods of improving the sound. Any suggestions are warmly welcomed.
Regards,
iang
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#1917636 - 03/28/08 08:45 AM
Re: Treatment for music venue
[Re: nee]
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Ethan Winer
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Registered: 06/12/00
Posts: 5406
Loc: New Milford, CT, USA
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The larger the room, the more treatment you need. No way around that. For a very large space you don't have to build hundreds of 2 by 4 foot panels. In that case it makes more sense to buy rigid fiberglass in 4 by 8 foot sheets. A few years ago I helped a local church treat their very large space, and they bought 4-inch thick 703 in 4 by 8 sheets. Volunteers wrapped them with nice fabric and hung them on the walls and ceiling.
--Ethan
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#1917979 - 03/28/08 04:56 PM
Re: Treatment for music venue
[Re: Ethan Winer]
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nee
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Many thanks Ethan. Can the panels be fixed directly to the walls, or would it help if they were attached to wooden battens to provide an airspace between panels and wall? And if we're primarily trying to control the boom, will the type of fabric wrap make any difference?
iang
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#1918193 - 03/29/08 07:34 AM
Re: Treatment for music venue
[Re: nee]
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Ethan Winer
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Loc: New Milford, CT, USA
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An airspace helps, as described in the forum FAQ. You really should read that because it answers all of your questions, plus the questions you haven't even asked yet. 
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#1918352 - 03/29/08 01:37 PM
Re: Treatment for music venue
[Re: Ethan Winer]
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nee
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Thanks Ethan. The FAQ is a wonderful piece of work, and I did in fact go over it a couple of times before posting - I'm slowly absorbing (pun possibly intended) it.
My confusion about the air gap is because you say:
"... fiberglass works better when spaced away from a wall or ceiling."
and then:
"... irregular absorption is most severe with thin absorbing materials, and gradually diminishes as the material is made thicker. You can avoid the reduction in absorption either by using thicker rigid fiberglass, or by filling the entire gap with material instead of using only a thin piece spaced away from the wall or ceiling. When the entire depth is filled, material is available to absorb all of the frequencies whose 1/4 wavelengths fall within that depth."
... which implies that it's better not to have an air gap. (I'm also unsure of your definition of "material".)
No doubt I've grasped this wrongly.
iang
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#1918658 - 03/30/08 07:16 AM
Re: Treatment for music venue
[Re: nee]
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Ethan Winer
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Registered: 06/12/00
Posts: 5406
Loc: New Milford, CT, USA
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In this usage "material" means rigid fiberglass or mineral wool or acoustic foam or acoustic cotton.
A gap is a "free" way to make an absorber behave as if it were twice as thick. The ideal air gap is equal to the material thickness, so 2-inch fiberglass with a 2-inch gap is almost as good as having rigid fiberglass 4 inches thick. The point about "thin" material is you don't want 1-inch fiberglass spaced two feet away.
--Ethan
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#1918833 - 03/30/08 01:25 PM
Re: Treatment for music venue
[Re: Ethan Winer]
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nee
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The ideal air gap is equal to the material thickness, so 2-inch fiberglass with a 2-inch gap is almost as good as having rigid fiberglass 4 inches thick.
--Ethan
Ah! Click! Thanks!
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#1920255 - 04/01/08 04:50 PM
Re: Treatment for music venue
[Re: nee]
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nee
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Ethan, I'm in a country that doesn't have the Owens Corning products (New Zealand). There are a couple of fibreglass products I have found and I'd value your opinion on which would be better:
80kg/m3 available only in 25mm thickness,
45kg/m3 available up to 100mm thickness.
Obviously price is a major factor, but could I assume that 50mm of 45kg/m3 fibreglass would have roughly the same effect as 25mm of 80kg/m3?
Thanks!
iang
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#1920648 - 04/02/08 10:20 AM
Re: Treatment for music venue
[Re: nee]
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Ethan Winer
MP Hall of Fame Member
Registered: 06/12/00
Posts: 5406
Loc: New Milford, CT, USA
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The only way to know for sure is to compare published absorption data. Most of these products are very similar. So what matters most is having enough thickness. 4 inches thick of any mineral wool is better than only two inches thick of any other mineral wool.
--Ethan
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