Originally Posted by 666666
Just wanted to follow up and mention that I took some of the existing Auralex foam panels and carefully measured / weighed them to try to determine the density... I arrived at a figure of about 1.5 - 1.6 pcf density. Sound about right? I measured / weighed several 4" wedge panels and several 3" wedge panels, came up with 1.5 - 1.6 pcf every time.
Again, I realize that density is not the only factor in determining a material's ability to absorb low end, but... it's all interesting.
Andre's right, of course. Rigid fiberglass or mineral wool is what you want for low end. Foam, regardless of density just isn't a stellar performer on the low end for the reason you stated...there's more to it than density.
The point Andre's making about predictability and repeatable results is a very important one. You want your treatment solution to be as dependable as possible.