what does polyfill do?

[tempest]

just wondering what is it exactly and why do you need it in a sealed enclosure. i didn't bother putting any in mine...

[92TripleBlack]

Polyfill gives the sub the feeling that it is in a larger enclosure. Sub boxes are supposed to be dead accoustically. This translates to the sub being fully seperated on the inside from the outside. The polyfill will trick the sub into thinking it is in a bigger box without loosing back pressure on the sub that it would loose if it really was in a bigger box. It is added by filling the box about half full with the stuff. I would try it. Costs $5 and is well worth the cost and very easy to reverse if you don't like it. I ususally put it in all sealed enclosures. In ported, they are already in an infinite box as they are open to the outside through the port so there is no reason for polyfill. Get if from a craft store. Its what grandmas use to fill up stuffed dolls with.
92TripleBlack :cheers: :smash:

[jfb]

Polyfill deQ's the enclosure. That is, it reduces internal resonances and smooths the frequency response making the speaker less "peaky".

[tempest]

thanks! i just realized that my enclosures are not completely sealed, but are ported. well, something to remember when i get enough $$$ for a sub.

[CO_Silver_Rush]

Is this something that I should add to a JL Stealthbox? Or should I leave it alone?

[92TripleBlack]

The JL is probably set up to work properly in its original form. This is however an easy change, just as easy to reverse, and will not hurt the JL so it can only hurt you to the tune of $5 to find out and let us know.
92TripleBlack :cheers:

[webdzynes]

Is there a difference in quality of this stuff? I used the speaker fill "sheets" from Radio Shack.

[dtorc4]

When a speaker compresses inside the box, the pressure increases, making the air inside warmer (we're only talking about a few degrees). The fibers of the fiberfill vibrate when the speaker moves, thereby cooling the air inside the box, therefore making the speaker operate as if it was in a bigger box. This happens because the pressure inside the box is not as great b/c of the cooler air. Pretty sweet, huh? :cool:
Fiberfill can be used in a ported box, but it will not yield as great of a result.
There is too much of a good thing. If you stuff too much fill into the box, it restricts the fibers' ability to vibrate. When you take the fill out of the bag, make sure you separate the fill well so that it is not tight. A good rule of thumb is approximately 1lb of fill per cubic foot of space. This will yield about a 35% "increase" in apparent box space (i.e. a 1 cu ft box will act like a 1.35 cu ft box).
I read this in an article in Car Audio and Electronics a few years ago and it has stuck w/ me ever since. :seeya