Box lining question

[Ruststang]

Is there any point to lining the inside of your subwoofer box with dynamat or undercoating? I work with a guy who says he did it with dynamat and it helps with the sound and I'm not buying it. I have every inch of my trunk lined with dynamat allready so thats covered I'm just wondering about the box insides.

[redgst97]

I have done LOTS of acoustical treatments within boxes, but they are to control/deflect back waves or standing waves.

This is usually done with some sort of foam product, or something like a Dynamat Dynaxorb, or whatever its called....a deflex panel.

[BanginJimmy]

I have used polyfill before but I can't see a use for spomething like dynamat.

[sina518]

you always want the inside of the box to be sealed were the edges of the wood meet so that the air doesnt leak out causing the box to rattles or sound like garbage, poly fill is usually used to make the speaker think it is in a bigger box than what it is. as far as what john said about using a foam product, well i think in his case its diffrent cause he competes so his music has to sound different but as far as the average jow who just wants a loud, brain rattling stereo i think what you have now is fine, also due to the fact that you say your whole car is dynamated so, i dont see why you would have to alter your box.

[Ruststang]

Ok cool thanks for the info guys. I was just curious since i have never heard of someone dynamatting the inside of an MDF box.

[lovinmydodge]

adding something that takes the back wave and shuts it down is the worst and most stupid idea i have ever heard. In a sealed box there is no need to worry about the back wave. and in ported boxes you don't want to deaden the inside of the box. Hell the only point to using a ported box is that when the sub plays the tuning freq or near it it allows the port to activate the rear wave giving you a bump in the amount of sound pressure.... stopping the back wave will basically decrease your total output... If you do anything to the inside of the box just hit it with some fiberglass resin and hardener. That will seal the insides up good as well as allow for a little better airflow. and other than that the rest of what I've seen here is crap!

[redgst97]

adding something that takes the back wave and shuts it down is the worst and most stupid idea i have ever heard. In a sealed box there is no need to worry about the back wave. and in ported boxes you don't want to deaden the inside of the box. Hell the only point to using a ported box is that when the sub plays the tuning freq or near it it allows the port to activate the rear wave giving you a bump in the amount of sound pressure.... stopping the back wave will basically decrease your total output... If you do anything to the inside of the box just hit it with some fiberglass resin and hardener. That will seal the insides up good as well as allow for a little better airflow. and other than that the rest of what I've seen here is crap!

You have suggested Parts Express as the place to get speakers and such.... Many of the enclosures they sell seem to come with some sort of box lining....

http://www.parts-express.com/pe/show...number=300-762
How does a layer of fiberglass help allow for better airflow?

[lovinmydodge]

Yes for home audio you have a small amount of acoustical dampening. because in home audio they usually have very little power and are designed to play in a large non acoustical environment. We are talking about car audio. With a ported box its designed to allow for the back wave to be utilized, so if you put something that removes the rear wave you have just made a sealed box with a hole... as for the fiberglass comment. MDF the should be used wood for building boxes isn't airtight so air will pass thru the box. adding a small amount of fiberglass will seal up the boxes porous wood and also allow the air movement to be channeled to the port. with having the vibrations being forced thru the port and not the wood, will allow the " fiberglass" to be used to create a better airflow.