Baffleing Sub box

[Kingrye]

I was thinking about baffeling my sub box by lining it with 2in bed foam. Ive herd of people using polyfill. Does any one know any thing about this. Its the same concept as putting a blanket in a bass drum. The only draw back in my case is it will make the volume of the box smaller. what do you guys think.

[eric77]

I dont know if bed foam is the same as polyfill, but polyfill will actually make the box seem larger than it really is. It can also eliminate standing waves I believe. You can also use pillow stuffing to do this.

[Kingrye]

i was thinking egg crate foam is similar to what they coat walls with in recording studios
It cant hurt any thing right?

[JettaGLXdriver]

poly fiber fill from the arts and crafts area works as good as anything and it totally proven.

[jester614]

Perfectly cubed boxes have been said to create destructive or constructive waves as they bounce off the back but you also have to realize that to get this standing wave to create a constructive or destructive wave your box would have to be over 30' big.
Some studios use deadening to help prevent these standing waves at higher frequencies. This would be true in smaller woofers, where the size of the box may actually be close to the size of the length of a complete wavelength at the frequency that it is playing.
As for deadening, if you're talking about polyfill, it is used to make you box seem larger than what is actually is, and I have heard, but have no experience with, that adding filler will lower the resonant frequency of a box slightly.

[Kingrye]

explain resonant frequency, if you could.

[SierraNevada40]

everything on earth has a resonating frequency. have you ever heard of the tacoma narrows bridge? it swung back and fourth because the wind was creating a frequency that matched the bridges own frequency. when you match somethings own frequency, it will double and often times destruct it.

[Bremsen]

Taken from the12volt.com

Resonant Frequency - Frequency at which there is a response peak, due to a specific interaction of inductive and capacitive circuitry in an audio devise or system

On a speaker response curve (looks like a dyno graph) the peak output is the resonant frequency. What jester is saying is that by adding polyfill, the peak output of your sub will happen at a lower frequency (ie 40hz vs 45hz) b/c the sub thinks the box is larger than it actually is.

[m lew]

Adding polyfill is a harmless experiment. You can buy a cubic foot of the stuff for $10 from Crutchfield which is more than what most boxes should need. I used about half a cf in my 1 cf box and it noticebly improved the low end response. No, you're not going to hear a change in the speaker's output, but it will seem like the box is producing lower notes on the order of a whole octave. If you don't like the new sound, just take it out.

[Mister Green]

or you can buy about 3 cu ft at walmart for around $2. It says "polyfil" on the bag, and has pictures of stuffed animals on it. Its all just polyester fiber, the same stuff the car audio places will assrape you for.

I have the walmart stuff in my box.