I just finished my 0.565 ft^3 fiberglass subwoofer box for the spare-tire cubby. It will hold my 10" Boston Pro LF... which Boston recommends a 0.5ft^3 sealed box for.

My question: I have a few extra bags of polyfill sitting around... supposedly polyfill makes a box volume "appear" sonically larger than it is. Has anyone used it? What effects will it have on sound, resonance frequency, etc...

Come on Pinky + MacGyver... I know you can help me!

 

I have actually read reviews on Polyfill that go both ways. Some installers say that yes it works, and some installers say no, polyfill does nothing.

My opinion on polyfill:
I have used polyfill in some custom kick panel enclosures I currently have in my SUV. The reason why I used polyfill, is because the enclosure I made for the component speakers that went into the kick panels was a little bit too small for the recommend size of the woofers. So, after a little research, polyfill was a inexpensive, and time saving alternative instead of re-building the enclosures. (This was my first time working with fiberglass, and I it took alot longer to make this than I expected, but I did learn from my mistakes!) So, I stuffed the enclosures with polyfill. Did it make a difference? I think so. The bass was a little smoother, and hit a little lower. So I do think it works.

From what I can remember from the articles I read, their is another type of fill out there that works alot better. What is it? I don't remember right now... let me try and find those articles... But if you have the polyfill right now... It can't hurt to use it.

Only my opinion.

 

Polyfill works by slowing down the sound waves in the box, which basically makes the acoustic equivalient of a larger box. Be aware, though, that you can only get about a 10-20% increase in size with padding, and too much will make the equivalent box even smaller.

If you use the sheet stuff, cover all sides, if possible. If you use the loose stuff, don't pack it in, fluff it up and lightly place it in there. You might want to staple in a couple of places, but make sure you fluff it up after stapling.

For tight spaces, like in the stook, polyfill makes a lot of sense. Glenn, feel confident that what you're hearing isn't just in your head (no pun intended)...polyfill really does work, and you'll find it in professional installations (by professional I mean concert halls, theaters, etc.).