Wondering about sound dampening and boxes

[phantom240 5,000+ posts]

Okay, ive been wondering about some things ive heard and seen. Searched and found no conclusive info on the subjects. Okay, first, ive seen and heard of ppl putting polyfill on the inside of their boxes saying it makes the sub hit harder or something. Is this true or are they blowing smoke up my āss? Also, ive seen ppl post pics of their boxes and they have poured resin inside the corners of the box... im guessing it seals it better. Can someone elaborate? last, i was wondering about the effectiveness of sound dampeners like dynamat or second skin if used inside the box lining the walls. Would that have any affect on the sound output or anything? I was jsut wondering, cuz i gotta remove my subs so i can re-seal my box... it has a major leak... i guess i should make my own next time eh?

Click to read more...

 

[PV Audio 5,000+ posts]

If you're using MDF, Dynamat would do nothing. All that deadening does is to add mass to the panels to lower vibration and resonance. Poly fill CAN work, you just need to put it in the right quantities.

 

[Ingleside 10+ year member]

Okay, first, ive seen and heard of ppl putting polyfill on the inside of their boxes saying it makes the sub hit harder or something.

from what i understand it "fools" the sub into thinking you put it in a slightly larger box by slowing down the pressure waves within the box. my old set up sounded a little cleaner once i put the right amount of polyfill in due to the fact that the box it was in was a bit small.

Also, ive seen ppl post pics of their boxes and they have poured resin inside the corners of the box... im guessing it seals it better.

yes

Last, i was wondering about the effectiveness of sound dampeners like dynamat or second skin if used inside the box lining the walls. Would that have any affect on the sound output or anything? I was jsut wondering, cuz i gotta remove my subs so i can re-seal my box... it has a major leak... i guess i should make my own next time eh?

it's not going to do much. you cant just try to fix things on a box sometimes.

sometimes you need to rebuild it or replace a panel.

 

[phantom240 5,000+ posts]

so the dynamat crap would be for like fiberglass boxes to keep em from rattling and cracking themselves?

 

[Ingleside 10+ year member]

so the dynamat crap would be for like fiberglass boxes to keep em from rattling and cracking themselves?

the dynamat crap is to be used on the inside of your trunk, doors, floor etc.....

dynamat and dynamat like products are made to deaden and add mass to panels that vibrate or resonate.

 

[PV Audio 5,000+ posts]

so the dynamat crap would be for like fiberglass boxes to keep em from rattling and cracking themselves?

It would have no effect.

 

[joeldirt 10+ year member]

sound dampening is for two reasons. With higher frequencies, batting will help prevent resonant distracting noise that is actually audible to an educated ear from the enclosure. Subwoofers generally do not carry this high of frequencies for the most part, so for that reason batting is not necesary. The second reason is that it slows down the air waves inside the box, giving the woofer an illusion that it is in a larger enclosure. If the air can't respond as quickly because of the batting in the box, it almost is like adding more volume to the enclosure in a sense. That way in a space saving design where volume isn't at your luxury, batting would be a suitable and inteligent solution to get lower bass response. As far as dynamat in a fiberglas enclosure goes... I tried it out of curiosity once just to see what the difference was, and there was no audible difference. The fiberglass wall was 3/8 to a half inch thick on a curved surface ( wheel well of a trunk) so it was ****ed sturdy. That is a waste of an already expensive product. It would be the best and most cost effective way to reduce rattling by proper bracing and proper layer build up.