Posted: Fri Apr 23, 2010 11:01 am
Airforceyooper wrote:I'm well aware of how deadening works Bill, thanks. lol. You don't have to be so defensive. The constrained layer stops reattles and lowers the resonant frequency of whatever it's stuck to. MLF
It doesn't really stop rattles, and it has a lot less effect on resonant frequency that you might think. Stopping rattles COULD be a side effect
Adding mass lowers RF, and stiffening raises it. CLD does both of those things so it kind of doesn't change the RF all that much. Besides, lowering the RF of something can be bad, especially if it was previously above the passband of a nearby speaker for example.
The TRUE use of CLD is to dampen vibrational/acoustical energy in the substrate by using sheer force to convert it into heat energy. Basically the foil layer is an actuator that thru the adhesive layer places pressure back on the substrate in order to lower the vibrational energy.
Your cheap CLD mats, that have mylar foil, pretty much do just lower the RF without adding much stiffening.
ALL CLD is not created equal, even if it has the same thickness, there are other factors.
I know that Don has developed the butyl compound used in his tiles, worked with the producer of the product to improve it many times over before selling it.
As far as testing against other products, I haven't gone farther than subjective testing at this point, I'm getting to the point where I realize it wouldn't be worth my time because no buddy gives a shit, they still buy 4x the amount they really need of the cheapest shit they can find and put it everywhere 2-3 layers thick. Its also very hard to reduce the variables in this test to properly prove which material is truly the best.
I can pretty easily show you that the cheap stuff is worse than the good stuff tho. Get 2 12x12" panels of sheet metal. Put a 3"x3" peice of deadner in the center of it hang them up by the corner and hit them with something. One will sound like a cymbal, one will sound a lot less like a cymbal.
