3000W Chinese Gensets Info.

professor95 wrote:
That is when I saw three blocks of acoustic sound deadening foam in the trash wagon.


Difference? Amazing!! I don't have my dB meter with me to give actual sound levels, but my ears tell me just two pieces of this stuff really make a difference.

GREAT FIND! That stuff is good. I use it to tighten up the bass in by stereo by reducing room resonances. It has a good NRC rating, and is ideal for lining a gen compartment. It doesn't do much to block sound, but it just sucks it up so it can't get out the air in or out passages. It also works as a baffle placed to block line-of-sight sound travel while still letting air get around it. I believe, since all gen compartments are open for air flow, that absorbing the sound is far more effective than blocking it. In a sealed compartment, blocking is best. At work, we used high STC-rated material to block electrical and mechanical noise producers, but had to add NRC-rated material when openings for air were needed. Partially blocking the openings with NRC stuff really made a difference.

One other thing.....I cobbled up air blocking thingies by boring a bunch of 1/2 inch or so holes in cardboard. I even did experiments that showed that the same area of opening through a bunch of holes resulted in less noise than with one same-sized opening.