copied/paste ....Stuffing a box with polyfill makes it seem larger and it all relates to thermodynamics. When polyfill is added to an enclosure, it changes the behaviour of the airspring in the enclosure from "adiabatic" to "isothermal". The term "adiabatic" implies that there is no heat transfer occurring. An isothermal process occurs once the polyfill has been added. As the air passes through the polyfill, the fibers wiggle and cause some of the energy created by the airspring to be dissipated as heat. This heats the surrounding air molecules warmer, causing the air to become less dense. Being that sound passes easier through a denser medium, the speaker interacts with your enclosure as if it is larger than it actually is. The effective increase in enclosure size can be as much as 40%!

This has some very obvious benefits that are inherent of a larger enclosure. Firstly, it becomes more efficient (a larger enclosure is always more efficient than a smaller one for any given driver). Second, the f3 (or the frequency at which SPL is down by 3dB) will be lower, providing a little bigger bottom end. While these are both great advantages, they decrease the effective damping of the speaker as well, meaning the speaker can be more likely to bottom out or over-excurt itself. Naturally, this is speaker, frequency, and power dependent. If used in a ported enclosure, you will also see the Fb (or the resonant frequency of your port) drop lower.

There are some additional worthy considerations. Adding polyfill to an enclosure can be a great choice. However, too much polyfill can be a bad thing. At a certain point, the stuffing becomes too dense and the fibers no longer wiggle. At this point, not only have you taken away the size benefit of adding polyfill, you have actually decreased the effective volume as the polyfill is now taking up room inside your enclosure. It is also worth mentioning that polyfill is not as effective in a large enclosure. Let's combine these two thoughts into two simple rules:
1. If the enclosure is less than 2.5 - 3.0 cubic feet in size, you should use no more than one and a half pound of polyfill per cubic foot available in your enclosure.
2. If the enclosure is greater than 2.5 - 3.0 cubic feet in size, you should use no more than one pound of polyfill per cubic foot available in your enclosure.

Specific examples of polyfill's effects on various enclosure sizes (with varying amounts of polyfill in each size) can be found in The Loudspeaker Cookbook by Vance ****ason or in an article written by Tom Nousaine for the March/April 1995 edition of "Car Stereo Review".

 

eeeer not qiute that simple, because polyfills mass itself is largely air, it is nothing new that polyfill will increase your dampening factor and allow you to push your sub harder, as well as give you actual sound production far below the factories frequency range, as apposed to a some what deep flapping sound. I know a site that did a very in depth test of this effect, both with sealed and ported boxes. I will try and dig it out of my bookmarks but that could take a wile, for now i have some charts of their results of their testing.[IMG][/IMG][IMG][IMG][/IMG][/IMG]

but even shown in these charts, you can have too much of a good thing.
once again i will try to find the original site because if nothing elese its a good read

swift

 

Audiojunkies website:
http://www.audiojunkies.com/blog/134...osure-resource

In ported enclosures it effectively lowers the tuning a bit as well.

Good stuff!

 

Well then that makes sense. Sorry about the arguement guys, I never thought about the thermodynamic application of it. It does make sense when the air warms up, but in a sealed enclosure where there are almost no air holes, warming the air would create a greater air pressure, wait a minute...Resulting in better compression...Okay, you guys got me, lol. It makes sense though! Thanks for the infor guys! Yeah I've never been against using polyfill, but I never took thermodynamics into consideration.

 

Here's how i had the box setup (the sub is old but i have my kicker in it)
http://www.youtube.com/watch?v=us53flyey3c

 

sundevil please enlighten everyone on this matter

 

Im going to keep my CVR for now, and get a L5 12' later on down the road. i will look into the fiberfill stuff. but for now, i just want to get my system operating again!