AudioCircle
Audio/Video Gear and Systems => The Acoustics Circle => Topic started by: Syrah on 16 Nov 2016, 08:51 pm
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Hi All,
I've finished a bunch of corner traps with OC 705 that I received (4" thick each, with the wall cavity stuffed with fluffy insulation). Since they had a bulk discount, I've got a good dozen extra 705 bats kicking about.
I'm wondering whether I should try making a soffit type trap for the front floor of my room. The soffit designs I've seen online seem to consist of solid Roxul type insulation in a 2' by 2' rectangle.
What would be my best design with the dozen 705s? I could make a box with 705 on the outside and stuffed with fluffy insulation on the inside? Or I suppose it could be a half box with double 705 on the top and front and nothing on the floor and wall, stuffed with insulation?
Any thoughts as to the best design? My goals are broadband bass absorption as deep down as I can get it.
Thanks.
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Build similar to corners, but I'd leave the space behind empty (don't stuff). Standard residential soffits extend 12 inches down from 8 ft ceiling and out 14 inches from the wall. Anything of a different size and they could look weird.
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One option is to double up the 705, to make 8" thick panels, but that's not really a soffit shape. And, 705 doesn't perform as well the thicker you make it (relative to other less dense materials). 3-6" thick seems to be the sweet spot.
So yes, if you "frame" soffits with 705, and stuff behind with regular fluffy fiberglass, I imagine that would work well. Would work even better for bass if you put some sort of membrane on the front face of the 705 that faces into the room.
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One option is to double up the 705, to make 8" thick panels, but that's not really a soffit shape. And, 705 doesn't perform as well the thicker you make it (relative to other less dense materials). 3-6" thick seems to be the sweet spot.
So yes, if you "frame" soffits with 705, and stuff behind with regular fluffy fiberglass, I imagine that would work well. Would work even better for bass if you put some sort of membrane on the front face of the 705 that faces into the room.
Interesting. What type of membrane would you recommend? And why does the membrane work for bass?
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Getting 705 with FRK is a common way to easily get a membrane happening. If you don't have the FRK then you can use various things. I've heard of people using cardboard, butcher paper, plastics.... it just has to be the right mass and stiffness to work correctly.
As far as how it works.... it's a physics thing. The membrane will tend to vibrate at lower frequencies, and then the fiberglass damps the vibration. This affects the low end absorption. Plus, the membrane is likely to become reflective at higher frequencies which is often helpful.
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What is FRK?
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Foil Reinforced Kraft paper. Rigid fiberglass sometimes comes with this on one side.
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Kind of like the paper from a brown grocery bag, with some foil glued to it, and the whole assembly glued to the fiberglass.
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Build similar to corners, but I'd leave the space behind empty (don't stuff). Standard residential soffits extend 12 inches down from 8 ft ceiling and out 14 inches from the wall. Anything of a different size and they could look weird.
Since when has "weird" looking bothered a true audiophile? :eyebrows: