<a href=showthread.php?s=&postid=7782550#post7782550 target=_blank>Originally posted</a> by BeanAnimal
Dynamat is a waste of time. Egg cartons are also a waste of time.
Dynamat is primarily for low fequency damping and comes in several forms. In esssence it is asphalt based material that damps the resonances of whatever it is stuck to. The problem is that it's damping characteristics are focused in the high energy bass region. In other words it is to keep your quarter panels from vibrating with your sub woofers.
Egg cartons are pretty much sonically transparent and will do little but take up room.
The best noise absorbing material for our purposes would be melamine foam. You can get this from most industrial suppliers or sound proofing companies. There is also very EXPENSIVE foam used in aircraft manufacturing, but expect to pay big bucks for that.
People are misguided in thinking that all "foam" absorbs sound. Instead the opposite is true, most foam products absorb very limited bands of sound.