# Polyfill question



## jivitup (Nov 2, 2009)

In a small sealed enclosure, are you supposed to glue or secure the polyfill to the box? Or just stuff it in there? If you are supposed to glue/secure it what did you use to do it?


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## naiku (May 28, 2008)

I think (could be wrong though) that you just stuff it in there. At least that is what I assumed when reading about adding polyfill to a sub box, and it is what I did with mine.


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## zblee (May 18, 2010)

naiku said:


> I think (could be wrong though) that you just stuff it in there. At least that is what I assumed when reading about adding polyfill to a sub box, and it is what I did with mine.


x2, that is what i did, no glue


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## Duncan345 (Apr 30, 2010)

Just stuff it in there. It's not going anywhere.


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## jivitup (Nov 2, 2009)

Thanks for the replies! Does it have to stay a minimum distance away from the sub?


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## [email protected] (Jun 12, 2008)

You can stuff it or glue it to the walls. Either will work, I usually line the walls with Eggcrate foam and glue that, then stuff the rest with loose polyfill.


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## havinnoj (Sep 9, 2009)

It will be fine. I stuffed a bunch of it in there and then used a sheet-type polyfill on around the magnet, spider, cone so none of the loose stuff would move around in there. Works well. No glue needed.


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## Robo65 (Mar 3, 2010)

jivitup said:


> In a small sealed enclosure, are you supposed to glue or secure the polyfill to the box? Or just stuff it in there? If you are supposed to glue/secure it what did you use to do it?


 I have read up on this topic for over 20 years. The correct way to install polyfil is to loosly stuff it into the box but making sure the area directly behind the subwoofer is clear of the polyfil cause you don't want the sub sucking in the polyfil material and blowin out your VC. Do NOT use fiberglass it ain't the same. By adjusting the amount of polyfil you use, you can actually make the sub think it is in a bigger box. I have read a ratio of 1.5lbs polyfil for boxes up to 3 cubic feet can make your subwoofer perform like it's in a box 30% larger. I hope this helps.


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## Oliver (Jun 25, 2007)

What kind of Ratio does that equal ? Robo65

EX: *1.5 pounds to 3 cu ft*


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## jivitup (Nov 2, 2009)

Thats 0.5lb/ft^3. I kept on reading around that 1lb/ft^3 was the right ratio??


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## Lanson (Jan 9, 2007)

1.25lbs per cubic foot.


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## Robo65 (Mar 3, 2010)

zblee said:


> x2, that is what i did, no glue


I do not think it's wrong to glue the polyfil, hell I've used my trusty ol hot glue gun on previous boxes to secure the polyfil mostly up in the corners of the box. I just wouldn't glue the entire polyfil to the inside. I hope this helps.
Robo


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## [email protected] (Jun 12, 2008)

Here is a great write up on poly fill

Ultimate Polyfill Subwoofer Enclosure Resource [audiojunkies]


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## radarcontact (Oct 28, 2010)

Robo65 said:


> ...The correct way to install polyfil is to loosly stuff it into the box but making sure the area directly behind the subwoofer is clear of the polyfil cause you don't want the sub sucking in the polyfil material and blowin out your VC. Do NOT use fiberglass it ain't the same. By adjusting the amount of polyfil you use, you can actually make the sub think it is in a bigger box. I have read a ratio of 1.5lbs polyfil for boxes up to 3 cubic feet can make your subwoofer perform like it's in a box 30% larger. I hope this helps.


This info is absolutely correct, to the tee! Except...I don't think 30% is realistic. I give myself about 15%. It's usually a tradeoff between the volume you lose through magnet size and bracing, compensated by fiber volume "increases". In other words, if you design the speaker box correctly, you can almost consistently ignore the additional space taken up by the misc items (magnet, bracing unless extensive) by loosely filling with fiber fill (Wal-Mart type is fine, BTW). It's basically a wash.

(I assume we're talking about a basic, sealed speaker enclosure)


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## beyondredline9k (Nov 28, 2010)

Thanks for the info


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## whitedragon551 (Oct 3, 2009)

I hate to bring this back from the dead, but Im taking on my first Polyfill application.

I have a 1 pound bag with a 1.1 cube enclosure that my Evo is going in. It doesnt seem like I can get the full 1 pound in without stuffing it. I thought it was supposed to be loose?


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## Lanson (Jan 9, 2007)

whitedragon551 said:


> I hate to bring this back from the dead, but Im taking on my first Polyfill application.
> 
> I have a 1 pound bag with a 1.1 cube enclosure that my Evo is going in. It doesnt seem like I can get the full 1 pound in without stuffing it. I thought it was supposed to be loose?


1.25 lbs per cubic foot is fine. It isn't really "stuffed" at 1 cube, 1lb. There is still tons of air in there, that's the idea of course. Keep going!


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## radarcontact (Oct 28, 2010)

whitedragon551 said:


> I hate to bring this back from the dead, but Im taking on my first Polyfill application.
> 
> I have a 1 pound bag with a 1.1 cube enclosure that my Evo is going in. It doesnt seem like I can get the full 1 pound in without stuffing it. I thought it was supposed to be loose?


Just stuff it loosely, don't worry about math equations. Stuffed, like a "stuffed" animal, as in to replace the air with the fiber-fill; not "packed". Should still be spongy.

You'll know.


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## whitedragon551 (Oct 3, 2009)

My box is only about .3 cubes off of ideal taking into account the transfer function of my car. I used probably about half a bag lightly stuffed covering all of the interior MDF. Good or no?


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