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Post by mrseven on Nov 2, 2016 13:22:26 GMT
Hi, I saw the plans for the bass traps on Ethan Winers site. They are designed to be fixed to the wall or ceiling by bolt. If I were to make these free standing, what would be the proper backing material in place of the wall? Thanks!
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Post by Hexspa on Nov 3, 2016 23:37:30 GMT
Hi mrseven.
If they're free-standing then no backing material is required.
A front-facing membrane is useful to get more low-end absorption at the expense of some mid-high absorption.
So, you'd use forward-facing membrane in non early reflection applications.
-m
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Post by rock on Nov 4, 2016 14:59:05 GMT
But if you're referring to the plans for resonant membrane absorbers using a plywood membrane, the back must be solid and screwed or bolted and sealed to the solid wall is best. For free standing, rigid 3/4 plywood or MDF. You only want the front membrane to resonate. Also, because these are pressure type absorbers (as opposed to velocity type absorbers), the best place for them is at the boundary (against the wall etc.) so free standing may not be the best except that you are free to move them around to find the best location if you are experimenting.
Now the bad news: this design is not recommended. The effective bandwidth is narrow, about and octave, and achieving accuracy to the center frequency is tricky. The recommended approach is porous absorbers as hexspa above describes. The front facing membrane is foil, plastic or paper that is spray glued to the front surface.
Cheers, Rock
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Post by Hexspa on Nov 5, 2016 12:52:03 GMT
Oh geez, I forgot about pressure absorbers gah
Don't know much about 'em. Never seen one in the wild.
I'd listen to Rock.
-m
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Post by mrseven on Nov 5, 2016 15:29:30 GMT
Thank you all for the replies. Very helpful!
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Post by Ethan Winer on Nov 8, 2016 17:48:49 GMT
Rock gave the right answers, as usual. I've made wood panel bass traps with a rigid back, and they work as well as when on a wall, but they're very heavy! And thick rigid fiberglass traps are better in most applications anyway.
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