# Keeping Polyfill in a ported box



## victor's gt (Dec 4, 2009)

Is it ok to use speaker grill cloth over the port to keep the polyfill inside the box?


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## fish (Jun 30, 2007)

You don't want to use loose polyfill in a ported box - it'll block the port. Get some polybatting & staple multiple layers to the walls of the enclosure.


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## 89grand (Nov 23, 2006)

Yeah, you don't really need any polyfill in a ported enclosure.


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## victor's gt (Dec 4, 2009)

89grand said:


> Yeah, you don't really need any polyfill in a ported enclosure.


I am using it to overcome .3ft^3 (my enclosure is a tad bit small)

I see plenty of people using polyfill in ported box. Some manufacturers even suggest it.


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## 89grand (Nov 23, 2006)

I wouldn't use it, plus who knows what it's doing to the tuning frequency. It's better left to sealed enclosures.


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## gymrat2005 (Oct 4, 2009)

could he use something like a variovent or small AP mat to make the box seem bigger, even though it's a ported enclosure? I know they are typically for sealed enclosures, but would it work for him?..that way he doesn't have to use any other type of box filler.


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## Austin (Mar 12, 2009)

Any filter on the port will cause noise and possibly even resistance that you don't want. I have used it in ported boxes and it helps a bit. I just stuffed it tight in between one of my braces and kept it away from the ports.


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## 89grand (Nov 23, 2006)

I don't see them working. An AP mat is designed to be vented to the outside of the car or in a sealed off trunk like an IB install. The variovent, I'm not sure how he'd ever calculate the "perceived' size of the enclosure after installing it, plus I think they should also be vented to the outside of the car, like an AP mat.


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## Ray21 (Oct 19, 2009)

fish said:


> Get some polybatting & staple multiple layers to the walls of the enclosure.


I'd do this.


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## audiogodz1 (Jan 5, 2010)

victor's gt said:


> Is it ok to use speaker grill cloth over the port to keep the polyfill inside the box?


As earlier suggested you'll want to put it around the walls, keep it off the port. I've been doing it since 1993 and it works very well to even out a stubborn sounding box in most cases. Good luck!


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## victor's gt (Dec 4, 2009)

Poly batting will do the same thing as polyfill for what I am trying to do? Which is make the enclosure appear slightly bigger?


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## chad (Jun 30, 2005)

not really


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## Thumper26 (Sep 23, 2005)

x2 to the poly batting. and I always used spray glue to stick it to the walls. it doesn't need much to keep it in place, just fluff it up before putting it down.


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## victor's gt (Dec 4, 2009)

Im a bit confused now....for ported box.....

Use poly batting to increase effective enclosure size
OR
Use polyfill to do so?


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## chad (Jun 30, 2005)

My vote is to make the enclosure larger.


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## fish (Jun 30, 2007)

chad said:


> My vote is to make the enclosure larger.



This is always the best option, but if you can't do that then polybatting is the better option for a ported box.

Chad, the quote in your sig, it took me a bit to realize where I heard it... Anchorman?


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## chad (Jun 30, 2005)

yep YouTube - SP by Odion


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## benny (Apr 7, 2008)

In BassBoxPro, the sim shows that stuffing a ported box lowers the tuning frequency slightly and knocks down the tuning peak. I stuffed my box to eliminate some boominess, but I made sure there was a clear path to the port opening and I stapled some grille cloth over the opening inside the box.


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## t3sn4f2 (Jan 3, 2007)

I have some Infinity Kappa home speakers that have a thick dense foam wall that divides the 8" woofer's enclosure. On one side is the woofer with some of the enclosure space and on the other is the port with the rest of the woofer's enclosure space. 

It's a fairly tall tower and uses a dome mid, so since the woofer plays fairly high they probably use it to keep midbass resonance down and to keep some of the midrange from coming out the port.


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## pionkej (Feb 29, 2008)

My opinion is you should try it both ways since polyfill is cheap. As long as you won't strip out the holes removing your sub, I would start with it empty (but go ahead and put something over the port--grill cloth or pantyhose both work in my experience) and then start adding polyfill. 

It obviously doesn't work in every situation, but I have had success with it in the box I built for my 300zx. I lost a bit of impact in the subbass to midbass transition but I also lost some of the boomyness and it was a good compromise for me. I put around 3 bags in a 3cu/ft enclosure and didn't experience any port noise even at low frequencies. 

Again, it may or may not work, but it wouldn't hurt to try and see.


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