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High density fiberglass as bass absorber?

I've read for days concerning various DIY bass traps. Tubes, resonating panels, Helmholtz resonators, and all manner of rigid fiberglass designs with and without air gaps and with and without limp mass membranes. For the moment I am interested in quick and dirty bass absorption with no regard for aesthetics. Rolls of insulation stacked in the corner are said to be useful.

From what I've been able to gather, generally the effectiveness of fiberglass products increases with increasing density. Owens Corning Atticat fiberglass insulation comes packaged in plastic bags having dimensions of about 9"X 20"x 38" (about 4 cubic feet of volume). The weight is about 35lbs. Therefore, as packaged, it has a density of about 9 pcf. With OC 705 having a density of about 5 pcf, would we not expect Atticat to be a bit more effective at bass absorption than OC 705 per unit volume?

I don't find any mention of anyone trying to use this product as a bass absorber. I'm gonna try it, but before I do, perhaps someone out there can tell me that it doesn't work or why it won't work. Anyone?
der
sns
3,068 posts
 
I use semi rigid fiberglass (Johns Manville Micro-Flex) in my DIY tube traps, highly effective. I suppose this could be a quick and dirty solution, just roll the fiberglass around something circular. Take the reflective foil off and glue the ends together, easy and very effective.
der OP
38 posts
 
The product is a bag of fiberglass, pretty tightly compressed and intended to be taken out of the bag and spread in the attic. No foil or backing. Its not a sheet or a roll or anything like that. Its unique feature is the high density as packaged. If absorbance increases with density (I believe it does), I am hoping that stacking these bags in a bass-heavy corner will be effective.

Shoot, I've heard of people using rolls of insulation still in the bags, and even trying to compress the rolls to increase density. In Atticat, we have pretty cheap and very dense fiberglass product on the Home Despot shelves. So I'm rooting for it.
sns
3,068 posts
 
I would be leery of anything in a bag, bags may be very reflective confusing soundstaging, perhaps affecting tonality. The reason I take the reflective foil off the semi rigid fiberglass. I too have read of people using the bags of insulation, hard to tell how effective or ineffective these schemes are without hearing them. If the insulation would hold together out of the bag it would be better. The guys I've seen using the roll insulation most often attach it to rather rigid screening so that it holds it's shape. You need a well defined inner space to be effective, that seems hard to attain with loose fiberglass.
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