Poly-Fill ?
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=20242
Printed Date: May 14, 2024 at 3:03 PM
Topic: Poly-Fill ?
Posted By: AudioBAHNvlcm
Subject: Poly-Fill ?
Date Posted: October 17, 2003 at 8:32 PM
does adding poly-fill to a sub box really make a difference? does anyone have any personal experience with it? and also, how much do u need to put into the box? thanks for the help
Replies:
Posted By: philaf
Date Posted: October 17, 2003 at 9:34 PM
i've never heard a big difference, but i have a friend that swears by the stuff. supposed to slow down the sound waves or some-such. if it does, slower soundwaves make deeper tones. hence, lower bass. although i can't tell for sure either way, there's nothing wrong with a little experimentation on your own part. you can get a big bag of the stuff in walmarts craft section for like $3. if you try it, make sure you let us know your take on it. cheers
Posted By: promodeepcycle
Date Posted: October 17, 2003 at 9:54 PM
it depends on the box design ..... usally on ported boxes ...... it does "slow" down sound waves.. typically getting rid of hard corners.. better resonance
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Posted By: Ketel22
Date Posted: October 18, 2003 at 12:54 AM
poly fill delays the sound waves to create a "larger" enclosure. using about an inch of polyfill on all sides can increase the relative box size by 20%. using more polyfill than that is not reccomended. also if the polyfill touches the heated magnet you get an aweful smell from the port and or enclosure.
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Posted By: DYohn
Date Posted: October 18, 2003 at 11:18 AM
To absorb internal standing waves and to prevent reflections into the woofer cone, some sort of acoustic dampening material such as poly-fill should be added. Adding this material to an enclosure will increase the apparent internal volume. This is important to note, especially with sealed box designs, since the enclosure should be filled close to 100% and equivalent volume increases of 10 to 25% are possible depending on the amount and type of material used, so you must undervolume the enclosure to achieve our target. For example, calculate the target volume of the enclosure and then undersize by 10% when you build it, and add a pound of poly-fill for every 1 cuft of enclosure volume. This will allow you to build a somewhat smaller enclosure for a given woofer.
Posted By: funnycar
Date Posted: October 18, 2003 at 10:38 PM
Ketel22 is right, definitely do not overfill the enclosure, the polyfill acts as an insulation then and overheats the magnet structure because the venting system of the voice coils can`t breathe.
Posted By: italnpimp59
Date Posted: October 19, 2003 at 7:37 PM
wow so polyfill actually increases the volume? i didnt know that, ive never used the stuff before but i always thought it took up airspace, but i did know it helps give deeper bass. well i learn stuff everyday from this site
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Posted By: AudioBAHNvlcm
Date Posted: October 19, 2003 at 10:50 PM
Ok, i hear some people saying you put in a pound of poly-fill for every cubic foot of box space you have, and then i hear, you put an inch layer on the inside. so which is it?
Posted By: crazyray
Date Posted: October 20, 2003 at 2:28 AM
Adding polyfill can increase the "apparent" box size by up to ~20% in a sealed enclosure. More than lining the walls of a ported enclosure may do more harm than good. https://www.win.net/audtatious/audio/fiber.html https://www.geocities.com/kreskovs/Box-1.html 
Read and enjoy.
Posted By: DYohn
Date Posted: October 20, 2003 at 10:11 AM
It's better to loosely fill the enclosure than to "staple" poly-fill to the sides of the enclosure. You want it to be loose and to fill the space (even though it will settle over time.) Use between 1/2 and 1 pound per cuft. I usually start with 1 lb and then if the bass is too "flabby", pull a little out. It works best in sealed enclosures, or in the sealed chamber of bandpass enclosures. I never use it in ported systems. The dacron quilt batting you can buy in fabric stores will work just fine, and there are several brands specifically designed for audio. NEVER use fiberglass house insulation!
Posted By: AudioBAHNvlcm
Date Posted: October 20, 2003 at 3:41 PM
okay so i went to Walmart and bought 2 bags of poly-fill. i stuffed my boxes with it. it didnt really make that much of a difference but i can tell that in the beginning of a thump, it thuds harder at first. if that makes sense.
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