# To polyfill or not to polyfill...



## lunchmoney (Dec 27, 2007)

I've got a sealed 1.3 cf box into which a JBL GTO 12" is going (volume does not take into account the volume that the driver will take up)... 

I also ordered a one-pound bag of polyfill, but a friend informed me that I don't really need it, since my box volume is pretty good for the driver...

I understand that the polyfill is useful if your box ideally wants to be larger... I don't have this issue, but I was under the impression that the polyfill also helped with overall SQ... but I could be mistaken...

The sub will see 300 watts rms, and will be in the trunk of my mazda 6.

Think I should bother with the polyfill? Or just return it?

Thanks


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## Thumper26 (Sep 23, 2005)

it makes the box seem larger.

did you order the acoustastuff from PE?

i say try it out and see if you like the sound. at the worst, you have it lying around for testing other boxes in the future.

if it is acoustastuff, can you compare it to the same amount of the cheap walmart polyfill?


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## 89grand (Nov 23, 2006)

You really don't need it, but you could try loosely stuffing the box, not using near the full pound just a few handfulls and compare it to without and see if there is a difference in sound.

Polyfill is cheap enough that I wouldn't even bother returning it. You could always use it for some other project later on.


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## lunchmoney (Dec 27, 2007)

Thumper26 said:


> it makes the box seem larger.
> 
> did you order the acoustastuff from PE?
> 
> ...


It's the stuff from Parts Express.

What are the pros/cons of making the box seem larger? The recommended volume for the sub is 1 cf...

Can I just stick all of it it in there loosely for now? I though you were supposed to use spray adhesive to adhere some of it to the inside walls, and then loosely stuff the rest...


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## 89grand (Nov 23, 2006)

lunchmoney said:


> It's the stuff from Parts Express.
> 
> What are the pros/cons of making the box seem larger? The recommended volume for the sub is 1 cf...
> 
> Can I just stick all of it it in there loosely for now? I though you were supposed to use spray adhesive to adhere some of it to the inside walls, and then loosely stuff the rest...



A lot of manufacturers rated enclosure sizes, aren't necessarily the best box for the sub, but often what is the smallest box possible while still sounding decent. Smaller boxes also increase power handling, but that won't be an issue for you.

I've always just stuffed the polyfill in the box, I never glue it to the sides.


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## Thumper26 (Sep 23, 2005)

yeah never glue it, just stuff it in. larger box makes the sub play lower.

it's an advantage when you don't have enough space for the box the sub needs. the polyfill helps get it there.

like most everything else, it's preference. give it a try and let us know what you think.


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## ErinH (Feb 14, 2007)

IME, it doesn't really make it play lower as it does make the response a little flatter. I used it a while back on a box to get rid of the boominess. Of course, that was a ported box and people were saying that I shouldn't use polyfill in a vented enclosure.


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## Thumper26 (Sep 23, 2005)

i use the quilted batting sheets in a ported box, and spray glue it to the side wall, just so it can't poof out of the port.

i try and use it behind round ports so they don't rattle at all.


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## FoxPro5 (Feb 14, 2006)

Search "polyfill and abmolech" or "polyfill and whiterabbit" 

http://web.archive.org/web/20041027...gracaraudio.com/caraudio/resources/fiberfill/


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## mvw2 (Oct 2, 2005)

bikinpunk said:


> IME, it doesn't really make it play lower as it does make the response a little flatter. I used it a while back on a box to get rid of the boominess. Of course, that was a ported box and people were saying that I shouldn't use polyfill in a vented enclosure.


Not shouldn't use, rather shouldn't use loose polyfill in the enclosure cause it can get sucked into the port. 

To me, polyfill is always good. It's not like it'll hurt anything, and it's not like it's expensive either.


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## ErinH (Feb 14, 2007)

mvw2 said:


> Not shouldn't use, rather shouldn't use loose polyfill in the enclosure cause it can get sucked into the port.


It was actually on ca.com. Dudes were implying that using polyfill in a ported box somehow makes the response worse.  
I used it with really good results.


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## lunchmoney (Dec 27, 2007)

Is it safe to say that it can only help? If so, I'll go ahead and stuff it in there.

Any downsides to it? (I've got a sealed box, I know there's a separate discussion here regarding ported boxes)


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## ErinH (Feb 14, 2007)

lunchmoney said:


> Is it safe to say that it can only help? If so, I'll go ahead and stuff it in there.
> 
> Any downsides to it? (I've got a sealed box, I know there's a separate discussion here regarding ported boxes)


It can't hurt, and it's not hard to do. Give it a go. Just make sure that when you do the comparison you put the box in the same place both times. And make sure that's the "final" position you'll use. Otherwise you'll get different results each time.


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## 89grand (Nov 23, 2006)

Try listening to it without, then add it and listen to it. 

It certainly won't hurt anything to use it.


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## JoelM (Nov 16, 2007)

No need to glue it but I've always used it in every enclosure I've built. It just seems to flatten out the response as someone else already stated. Enclosures sound kind of "hollow" without it to me.


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## Thumper26 (Sep 23, 2005)

lol, so how much do you need with an IB setup?


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## 89grand (Nov 23, 2006)

Thumper26 said:


> lol, so how much do you need with an IB setup?


Depnds on the size of your trunk.

It could be anywhere from 100-1000 pounds.


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## GlasSman (Nov 14, 2006)

Thumper26 said:


> lol, so how much do you need with an IB setup?


You call it the cotton ball install.


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## Thumper26 (Sep 23, 2005)

lol, i could do a "snow trick" instead of a "hair trick"


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## lunchmoney (Dec 27, 2007)

Thumper26 said:


> lol, so how much do you need with an IB setup?


3 good-sized dead sheep. Works beautifully.


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## durwood (Mar 7, 2007)

FoxPro5 said:


> Search "polyfill and abmolech" or "polyfill and whiterabbit"


 

http://www.diymobileaudio.com/forum/showpost.php?p=315575&postcount=18



> Enclosure's use the compliance of air (non linear) to change (add) to the drivers suspension. By increasing the suspension tension, we RAISE the Fs.
> Using polyfill converts more of the rear wave to heat Aperiodic for example will loss 3 dB to heat), this therefore decreases the compliance, at the expense of loss to heat.
> It can change the rolloff in a sealed enclosure from 12 dB to 6 dB for example.


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## Oliver (Jun 25, 2007)

On the sheep thang..baaadd idea !

Stuffing material :
fiberglass yellow
acousta-stuf
long haired wool fiber
fiberglass pink
polyfil

Why so many choices ?

Gasoline = racing fuel , premium , midgrade, regular, Sunoco economy  

Different octane ratings = do they all sound the same in your car, does it run the same on higher octane?

It's up to you !


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