I'm planing to build a pair of sub risers 18" tall 20" wide and deep. To get a better idea of what I mean I'll refer to the ACS subtraps which can be found here: ASC Home Theater Acoustics: SubTrap
Below the sub there will be a cavity that I plan to dampen to reduce the energy of the vertical node. My question is what material would be most effective to dampen specifically between 20-60hz in the 18x20x20 space given? (which will end up being closer to 16x19x19 of actual space for dampening material) Traditional NRC absorption coefficients does little to help me seeing how the range I'm looking to dampen is well below the tested range. I know nothing will be truly effective that low, I'm not looking for perfect absorption, only the best of the options available in the range I'm looking to dampen. I'd be more then willing to test non-absorption methods for dampening, but only if they would be more effective in the space given. Any input would be welcomed. Thank you.
Edit: One other question I forgot. I plan to wrap the sides with a fabric for aesthetic reasons. I know at higher frequencies that higher thread fabrics can reduce the effectiveness of dampening material they are placed over, which is why burlap is transparent. Would this still apply to 0-60hz? I can understand how it would impede air flow but it almost seems like the there is so much energy involved that it would be negligible. I would prefer a higher thread fabric, but I won't sacrifice acoustics for aesthetics.
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Below the sub there will be a cavity that I plan to dampen to reduce the energy of the vertical node. My question is what material would be most effective to dampen specifically between 20-60hz in the 18x20x20 space given? (which will end up being closer to 16x19x19 of actual space for dampening material) Traditional NRC absorption coefficients does little to help me seeing how the range I'm looking to dampen is well below the tested range. I know nothing will be truly effective that low, I'm not looking for perfect absorption, only the best of the options available in the range I'm looking to dampen. I'd be more then willing to test non-absorption methods for dampening, but only if they would be more effective in the space given. Any input would be welcomed. Thank you.
Edit: One other question I forgot. I plan to wrap the sides with a fabric for aesthetic reasons. I know at higher frequencies that higher thread fabrics can reduce the effectiveness of dampening material they are placed over, which is why burlap is transparent. Would this still apply to 0-60hz? I can understand how it would impede air flow but it almost seems like the there is so much energy involved that it would be negligible. I would prefer a higher thread fabric, but I won't sacrifice acoustics for aesthetics.
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