|
There are a few things I look for. One is the difference between the peak amplitude of the main resonant mode of the bare metal compared directly to the damped metal. Dynamat reduces peak amplitude by around 11db, while stinger reduces it by about 8db.
I also look at the steepness of the decay. This is easier for me as I can use rew and change gate times to see when the resonant mode decays into the noise floor. But, dynamat does decay faster, which is good.
It's important to note that all damping products are narrow band treatments, ie they only work well at the natural frequency of the panel they are applied to.
I will be retesting stinger, as I have enough material to test multiple runs of most products I have before finalizing the report. When I talk +/- 1db, I'm talking strictly about the reduction in peak amplitude with the same product. For instance, I tested 3 samples of SDS CLD Tiles a few months apart, and the difference in that reduction was within a db of each other.
Because there is an inherent error factor, I generally refuse to say a product is better than another unless it performs better than another by 3db+, and/or decays faster. In the case of dynamat vs raamat, dynamat decays about 20-30ms faster. Not a lot, but it's enough to make a difference when combined with the reduction in peak resonance amplitude.
I'm actually leaving town this weekend for vacation, but when I get back, I'll fire up rew and get some more detailed views that will show the difference in decay between products.
|