frost king mod
It also does a fairly good job of insulating from temperature.
Alternately, there is a material called Ensolite, which is a thick closed cell foam. It's more effective than Frost King, as well as cheaper. It can be had from a company called raamaudio. One single layer, like frost king, is not that effective against lower frequencies. This one is NOT self adhesive.
There are more effective products, such as Second Skin's luxury liner. This is very expensive and heavy by comparison - its a thick open cell foam with a vinyl backing. This does a good job of attenuating frequencies down to 200hz or so, and a somewhat decent job under that. It's also hard to get panels to fit right after using it.
I've used all three products before.
Also with this type of material, you must cover EVERYTHING. Think of sound like water. One "leak" can let a lot in.
I'd start with Raamaudio. Both the BXT (base layer, damping material) and Ensolite (closed cell foam) are excellent and fairly priced products.
Rick over there is very helpful.
And whatever you do - stay the hell away from elemental designs dampening stuff. It's ca ca.










