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is there a definitive answer on polyfill?

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=98081
Printed Date: May 05, 2024 at 11:39 AM


Topic: is there a definitive answer on polyfill?

Posted By: dtundra578
Subject: is there a definitive answer on polyfill?
Date Posted: October 18, 2007 at 11:54 AM

I did some searching and found some useful posts but nobody actually identifies if you SHOULD or SHOULDN'T use the stuff. Or when should it be used? If you can avoid using it, is that a better way to go? If there is a thread answering these and I missed it please hit me up with the link. Thanks



Replies:

Posted By: haemphyst
Date Posted: October 18, 2007 at 12:49 PM
If the box is too small, you CAN use it. If the box is too large, you SHOULDN'T use it.

At most, though, polyfill can compensate for somewhere around 10% of the total volume; i.e. it'll make the box "appear" up to 10% larger.

In large boxes, it can help prevent/absorb standing waves, but I'm referring to LARGE boxes.

If recommended by the manufacturer, use it.

As you can see by the above scenarios, there is no definite answer.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: dtundra578
Date Posted: October 18, 2007 at 2:15 PM
maybe not definitive, but a heck of a lot better than the speculation or offhanded opinions in other posts. Thanks!

So is the "10%" effect realized because the polyfill distributes the sound waves? If so are there other ways to achieve this? For instance through the use of other sound dampening materials inside the box? Suggestions on others to use if so?




Posted By: DYohn
Date Posted: October 18, 2007 at 2:26 PM

The apparent size increase is caused by the additional paths created by the fill material that the air inside the enclosure must pass through.  It has nothing to do with any impact on the actual sound waves, it is a physical effect on the air.  Longer path between front and back of enclosure = larger enclosure.

As far as a "definitive" answer, I say build your enclosure, test the system with and without fill, and use whichever gives the best results.



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