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PostPosted: Wed Nov 23, 2011 4:36 am 
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Hi! I'm looking forward to building a broadband bass trap to hang in the front wall of my mixing desk. I would like it to absorb bass frecuencies as the measurements I have done of my room with REW peak at 60Hz and 144Hz and have a dip in 77 Hz. I'm a newbie but I have made my research in the web, I would like to know what density of Rock Wool should I use for 4" bass traps of this characteristics. In my local store I find 144 Kg/m3(9 lb.pcf) and 80 Kg/m3(5 lb.pcf) . Thanks, any other suggestions wil be helpfull.


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PostPosted: Wed Nov 23, 2011 2:46 pm 
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Hi hernangil. Please check the forum rules for posting. You seem to be missing something! :)

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In my local store I find 144 Kg/m3(9 lb.pcf) and 80 Kg/m3(5 lb.pcf) . Thanks, any other suggestions wil be helpfull.
Both of those are way too dense. For bass you need something much lighter, around 40 kg/m3.

Having said that, absorption will not do much for such low frequencies, unless it is very thick, and/or spaced a long distance away from the wall. A quarter wave at 70 Hz is already 4 feet, so theoretically you should space that insulation 4 feet from the walls, for maximum effect.

- Stuart -

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PostPosted: Tue Dec 06, 2011 7:38 pm 
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So as far as I understand, 40 kg/m3 is the best variant. But what about a bit heavier, 60 kg/m3 which I'm going to use)?


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PostPosted: Tue Dec 06, 2011 11:13 pm 
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Contrary to popular belief, higher density is NOT better for bass: it is WORSE. For good bass trapping, you want lower density.

- Stuart -

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