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View Full Version : poly fill question?



s.l.a.b
01-14-2012, 10:46 AM
i have a ported sub box , and i know poly fill is usually used for compact sealed boxes. somewhere on a website i read that poly fill can also be used for ported boxes but im not sure about that so my question is if thats true?

ThatChevyGuy
01-14-2012, 10:58 AM
You would have to use some adhesive to keep it from blowing out the port. In ported boxes it acts differently than sealed. I tried it and had no different results in a ported enclosure. Sealed, thats a different story, my low notes came out and the subs had a tad more excursion.

DoesDad
01-14-2012, 11:48 AM
The Kicker boxes with the CVR's and Comps have polyfill in em right from Kicker. Can't say if there's a difference either way though...

Flipx99
01-14-2012, 11:59 AM
What are you trying to accomplish?

wenn_du_weinst
01-14-2012, 12:10 PM
Poly fill is always a crap shoot. It may do something audible and it may not. The only benefit to it is stop standing waves.

UMWDawg92
01-14-2012, 12:22 PM
I've had good results using polyfill in ported boxes but you have to make sure it stays clear of the port so it doesn't clog it up or blow out.

UMWDawg92
01-14-2012, 12:30 PM
Poly fill is always a crap shoot. It may do something audible and it may not. The only benefit to it is stop standing waves.
not correct for subwoofers... with subwoofers the polyfill actually tricks the woofer into thinking the enclosure is larger than it really is by dissipating heat generated inside the enclosure. Normally without the fill the heat causes the air to stiffen in the enclosure but with some of that heat getting dissipated the air doesn't stiffen as much. This in turn tricks the woofer into performing like it is in a larger enclosure.

ThatChevyGuy
01-14-2012, 12:34 PM
I've had good results using polyfill in ported boxes but you have to make sure it stays clear of the port so it doesn't clog it up or blow out.

What kind of results?

UMWDawg92
01-14-2012, 12:41 PM
What kind of results?
I've noticed with some woofers I've gotten them to play lower and it sounds cleaner on the low notes... I've only done it with home subs, never tried it in my car but I'm assuming I'd get the same results. It is also woofer dependent since some subs are much more sensitive to enclosure size than others. Subs that are more particular to what size of enclosure seem to have more audible results.

wenn_du_weinst
01-14-2012, 12:46 PM
not correct for subwoofers... with subwoofers the polyfill actually tricks the woofer into thinking the enclosure is larger than it really is by dissipating heat generated inside the enclosure. Normally without the fill the heat causes the air to stiffen in the enclosure but with some of that heat getting dissipated the air doesn't stiffen as much. This in turn tricks the woofer into performing like it is in a larger enclosure.

no your not right, that is just a byproduct of using it. The correct usage is to dissipate standing waves.

UMWDawg92
01-14-2012, 12:53 PM
no your not right, that is just a byproduct of using it. The correct usage is to dissipate standing waves.

dissipating standing waves isn't worth the effort in a subwoofer the low frequencies hardly have any standing waves to begin with due to the wavelength being so long. Most people use polyfill in subwoofers because they have a smaller than optimal enclosure. Now when using fill with a mid then yes it's primary function is to absorb standing waves.

wenn_du_weinst
01-14-2012, 12:57 PM
most people use capacitors to supplement their electrical systems as well doesn't make it right.

ThatChevyGuy
01-14-2012, 01:00 PM
I have a sealed box with two 15s in it. They would not hit lows below 38hz. I filled each chamber with 1.5lbs of polyfill. My roof shakes on low notes now :)

UMWDawg92
01-14-2012, 01:10 PM
most people use capacitors to supplement their electrical systems as well doesn't make it right.
how is it not correct to use polyfill to make a small enclosure more optimal? It has been proven time and again that in many cases it can make a big difference in how low the woofer can play... So using it to get rid of standing waves is the only reason you should use it? Would you explain why it shouldn't be used for another reason?

wenn_du_weinst
01-14-2012, 01:13 PM
It's not correct because it's a band aid. The correct way is to build the correct enclosure before hand. Your also ignoring the fact that standing waves make the enclosure seem smaller and inhibit low end response and clarity.

ciaonzo
01-14-2012, 01:19 PM
It's not correct because it's a band aid. The correct way is to build the correct enclosure before hand. Your also ignoring the fact that standing waves make the enclosure seem smaller and inhibit low end response and clarity.Jesus, dude. Please go read a book or get some practical experience.

UMWDawg92
01-14-2012, 01:25 PM
wave lengths in low frequencies are too large for standing waves to be a problem in a subwoofer, the waves never even fully develop in the enclosure. For example the wavelength for 100hz is over 3 meters...

snyderd758
01-14-2012, 03:19 PM
Read This:http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=2&ved=0CDsQFjAB&url=http%3A%2F%2Faudiojunkies.com%2Fforum%2Fblog%2 F4777-ultimate-polyfill-subwoofer-enclosure-resource.html&ei=idQRT_f_N4WwiQKdj5nhDQ&usg=AFQjCNHuahSChU6oPQy-BESReyKcX5BUQw&sig2=aVBRWRAVRWoHzMunta5VPw Also in my experience stuffing a ported box doesnt work to well even if your enclosure is smaller then optimium. Just my experience though.

snyderd758
01-14-2012, 03:41 PM
I have had great results in sealed enclosures everytime though.