Nordo
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Posts: 118
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Post by Nordo on May 18, 2008 2:12:20 GMT -7
I am currently building my IB sub which will be located in the floor of my Home Theatre, between joists. The details with photos is here ibsubwoofers.proboards51.com/index.cgi?action=display&board=projects&thread=1087&page=1. The joist area is an open-air crawl space. I have a cheap source of 17mm structural plywood which I am building my manifold iwth. I am also going to line the underside of the joists with the same 17mm plywood (like a ceiling), mainly to help isolate the rear external sub sound from the front sound emitting from the manifold into the home theater. My question is, before I fix the ply sheets to the joists, is there any absorbtion material worth placing between the joists that will help isolate the rear and front IB sounds?  My understanding is that materails such as fibreglass/polyester batts don't do much for absorbing low frequency sounds. |
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Post by fvoelling on May 19, 2008 6:55:55 GMT -7
I'm not quite sure what you're trying to accomplish, but check out Ethan Winer's web site for info on low frequency absorption (and acoustic treatments): www.ethanwiner.com/acoustics.html |
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Post by ThomasW on May 19, 2008 6:59:43 GMT -7
Insulation won't do anything because it can't be thick enough to absorb the low bass
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Nordo
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Post by Nordo on May 19, 2008 14:17:42 GMT -7
I'm not quite sure what you're trying to accomplish, but check out Ethan Winer's web site for info on low frequency absorption (and acoustic treatments): www.ethanwiner.com/acoustics.html Thanks for that. I've actually been to his site a while ago. I forgot about it. All I'm trying to do is separate the back wave from the front wave. At the moment the only separation is particle board floor and carpet. The 17mm plywwod is cheap, so for a small price I can add a 250mm compartmentised void and 17mm plywood to the floor system separating the two sounds. |
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Nordo
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Post by Nordo on May 19, 2008 14:19:23 GMT -7
Insulation won't do anything because it can't be thick enough to absorb the low bass Thanks Thomas. I didn't think normal insulation would do much for low frequencies. Just wanted to make sure. |
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Post by chrisbee on May 19, 2008 14:36:59 GMT -7
Much thinner plywood or even hardboard would absorb low frequencies by sympathetic vibration. Your 17mm would isolate to some degree but would be connected to the same jousts as the floor above. Rockwool is heavier than fiberglass wadding so would further improve isolation at some cost. It is most unpleasant working with insulation fibre overhead so I'd avoid this if possible. Or delegate responsibility for that work to somebody else. ;D
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Nordo
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Post by Nordo on May 20, 2008 6:04:34 GMT -7
Much thinner plywood or even hardboard would absorb low frequencies by sympathetic vibration. That's an interesting thought. Obviously thinner plywood would be cheaper. 4mm ply is commonly used in the building industry in my area (used as wall bracing against cyclones). Your 17mm would isolate to some degree but would be connected to the same jousts as the floor above. Rockwool is heavier than fiberglass wadding so would further improve isolation at some cost. It is most unpleasant working with insulation fibre overhead so I'd avoid this if possible. Or delegate responsibility for that work to somebody else. ;D I put in all the fibreglass insulation in my home theatre walls and ceiling in hot humid weather. The sweat makes the fibreglass stick in the worst places. My wife loves listening to movies and music in the home theatre, but I have trouble asking her to hold the end of a tape measure, let alone stuffing fibreglass or rockwool inbetween joists.  |
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Post by ThomasW on May 20, 2008 6:53:33 GMT -7
All I'm trying to do is separate the back wave from the front wave. At the moment the only separation is particle board floor and carpet. Here's a thought. Setup and run the IB, see if you actually have a problem, if you do we'll fix it. Bass traps like those sold by Ethan aren't the solution for this kind of problem. |
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Nordo
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Post by Nordo on May 20, 2008 14:40:29 GMT -7
All I'm trying to do is separate the back wave from the front wave. At the moment the only separation is particle board floor and carpet. Here's a thought. Setup and run the IB, see if you actually have a problem, if you do we'll fix it. Bass traps like those sold by Ethan aren't the solution for this kind of problem. OK Thanks Thomas. If I have any problems, I'll post them in my project thread. ibsubwoofers.proboards51.com/index.cgi?action=display&board=projects&thread=1087&page=1 |
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