Adding Polyfill to an enclosure
 

The first thing that comes to mind with Polyfill is to add
it to an enclosure and TRICK the woofer into thinking
it is in a larger enclosure...

first of all a Sub Woofer is NON LIVING...it does not think
it is in a larger enclosure when polyfill is added..

I have experimented with Pollyfill in all sorts of enclosures
and these are my findings

Polyfill does 3 things

#1..
Polyfill dampens the echoing sound waves inside the enclosure...
a thin layer on the walls of an enclosure will reduce the amount
of soundwaves rebounding off of the inner enclosure walls and
it also reduces the amount of soundwaves rebounding off of the
back of the woofer cone...

in a perfectly square enclosure it will
reduce the amount of standing waves...

used correctly it will deaden the sound between the notes
creating a smoother sound from the front of the cone

#2...
Polyfill eats up inner volume...if your enclosure is too small and
you add a pound of pollyfill you will reduce the inner cf3 of the
enclosure and the output and low end extension will decrease
doing the exact opositte of the desired effect

#3...
Polyfill traps heat...it works like insullation
in high power systems adding polyfill will
increase the inner temperature of the enclosure..
this is not good for those who like to pound their subs
hard for long periods of time


I have read articles by Richard Clark in Autosound Magazine
regarding on pollyfill and his comments were there was little
or no audiable difference by using pollyfill in an enclosure

this subject is highly controversial and is surrounded by
many different opinions

these opinions are my own...done with several different types
of enclosures and woofers....

there is no substitution for a properly made enclosure....





here is an article by Richard Clark (from Autosound Magazine)




Richard Clark11-14-2002, 12:07 PM
guys--------stuffing the box with polyfill has the effect of converting SOME OF THE PRESSURE CHANGES INTO HEAT-----adiabatic means the the system would be loseless regarding applied energy and really does not relate to pressure specifically-------with any spring (except a textbook perfect one that does not exist in nature) there is at least some isothermal effect------the air in the box is a reactance (spring) and when energy is applied (the spring is squeezed)------ the spring returns the stored energy when released------since there are no perfect springs all the energy is not returned-----the energy is lost as heat when the material in the spring flexes------this is no different with an air spring in a woofer box or a car suspension spring------the polyfill makes the box a more lossy system by absorbing SOME OF THE ENERGY by converting it to heat-----that leaves less spring pressure to push on the speaker cone------but the system by no means becomes totally isothermal (meaning all the energy would be converted to heat)-------if it were the box would behave like it was an infinitely large resistance and would resemble a transmission line-----------bottom line?????-------like i have posted about a jillion times-------the effect is subtle at best and does not make a very large (if any) audible difference..........RC

[ November 14, 2002, 12:09 PM: Message edited by: Richard Clark ]

thnx for sharing ur insight with us thumpper!

since you're reading...read this as well. I agree that there is little audible difference, but in my case it was noticable...slightly deeper.

http://www.audiojunkies.com/blog/1348/ultimate-polyfill-subwoofer-enclosure-resource

with the small sealed enclosures I did notice a small difference..I only go this route
in one of those small custom stuffed in the corner sealed fiberglass enclosures in
places where space is a real issue
it is basically a bandaid for an out of wack box...I know some manufacturers recommend
pollyfill in sealed enclosures but they are usually really small to fit in most vehicles

in reality if some woofer companies recommend the enclosure sizes that were best for performance
they would never sell the product

although there are some woofers that do like the small enviroment


like I said..it is highly controversial and opinionated but this is a good debate
to get things hopping around here:smilie_da

When it comes to sealed enclosure, the biggest difference that I've ever heard was having acoustic felt vs not having acoustic felt on all the inner walls. The difference was day and night. Needless to say, having the felt truly dampens internal reflection. It's definitely more significant than having polyfill. Regardless, I have felt and polyfill in my box and I can't live without them.

My enclosure is definitely on the smaller side...1.7 cubes for 2x12" type R's. It's to Alpine specs, and it pounds...much louder than I'd ever listen to it for any prolonged amount of time. It plays 20hz tones with enough authority to be satisfying...that is if you like super low bass, it's forte is it's incredibly tight, punchy bass...kick drums, bass guitar, and tom toms sound fabulous. My prior box was a 3.5 cube ported with 3 12's and 1200 watts, and this one is slightly less noisy with the same power. Can it get louder? ofcourse it can! Do i need it to? Hell no!

I wish I was happy with a small sealed box and one sub......it would
save me a ton of money and the car wouldn't be draging on the ground
from the weight of all the equiptment

I remember a guy coming over with a ported enclosure stuffed with pink
insulation....when the sub pumped little particles would float around the interior

can anyone say itchy:eyes:

Pink insulation = fiberglass = bad....

I'm surprised that ppl can't see the difference between fiberglass-fill and poly-fill LOL I hope that person didn't try to DIY pillow out of fiberglass-fill.

I put dynamat in mine...its weird how much of a difference it made...the sub (1 JL W1v2) sounds totally different...in a good way!

I have used carpet underlay a few times to line the enclosure....
you have to account for the displacement with the build but it
really created a dead sounding enclosure
also tried the spray insulation
(the hardening foam that is used to insulate campers exc.....)

lining an enclosure that is lacking bracing will reduce the ringing