Polyfill... too much?

[busky2k]

I've got a 2 cu ft sealed box with an Adire Tempest and I decided to polyfill it. I bought 2 x 1lb bags of the stuff and I can only get 1 bag worth in! I know I'm sposed to use at minimum 2lb in 2cu ft but I'll be really squashing in the other lb. Is this right? I figured if its so squashed it wouldn't work as well?

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[bigbassman Premium Member]

squash it in there, just don't crowd inside the sub's basket..

Loyd L.

 

[snoopdan 5,000+ posts]

lol, just try it with 1 bag first....see how it sounds.. polyfill is tricky sometimes, you got to play with it if you want it to behave right.

 

[ViperGuy 10+ year member]

Good timing, I was just going to post about this. Does pollyfill really work, will I hear a difference?

 

[coolahan 10+ year member]

Good timing, I was just going to post about this. Does pollyfill really work, will I hear a difference?

Yes.

 

[bibby 5,000+ posts]

From what I uderstand, polyfill makes the sub think the box is bigger than it really is. Kindof the opposite of what it actually does, by taking up airspace. //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[busky2k]

Alright I'll jam the rest in there. Just figured it works because the fibers absorb some of the wave's energy and thus simulates a bigger box. But because its crammed so tight it doesn't seem as if the fibres could move at all!

 

[Volenti 10+ year member]

From what I uderstand, polyfill makes the sub think the box is bigger than it really is. Kindof the opposite of what it actually does, by taking up airspace. //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

The change in resonant frequency (apparent enclosure volume increase) is actually pretty small, on the order of 2-3hz, it's the increased damping that the fill provides that causes the change in the subs sound.

The air in the sealed enclosure acts like a spring, when you add fill to the enclosure it acts like the shock absorbers on your car, restricting the movement of the "spring".

note; a well built enclosure with no fill can be up to 3db louder than a filled one, just keep that in mind.

 

[hemmer05]

from what ive heard polyfill also turns the energy into a type of heat energy which helps the subs reach their max excursion. idk if that is correct tho

 

[ViperGuy 10+ year member]

I just bought two 20 oz bags, I hope it works.

 

[CBFryman2 5,000+ posts]

The change in resonant frequency (apparent enclosure volume increase) is actually pretty small, on the order of 2-3hz, it's the increased damping that the fill provides that causes the change in the subs sound.

//content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

Filling airspace with fiber does one of two things (well a little of both always, but its purpose is one of the two). First it vibrates with the sound and disipates sound energy as heat. Why is this good? It is the equivilant of having a larger airspace. In the polyfill instance it you have less energy in a given volume be cause some of the energy is disipated, in a larger enclosure you have less energy in a given volume because you have the same ammount of energy in a larger area.

That didnt really make much sence at all, but that is what is going on.

Fiber filling will also disipate sound vibrations as heat slowing the speed of sound down. In this instance it is very helpfull in enclosures where the frequincy the driver is playing can actually exist as a wave, and not just pressure changes. It also makes the 'length' of a transmission line or quarter wavlength enclosure increase.