Polyfill and sub enclosure questions

[DDFrontier 10+ year member]

I have two Pioneer 8" subwoofers (model TS-W203C 4 ohm) in a sealed enclosure. Pioneer recommends 0.5 cubic feet of airspace per subwoofer. I have them in a small sealed box with 0.9 cubic feet of shared airspace (no divider). The subs sound fine at most frequencies, but struggle when going down low and sometimes sound 'boomy'. I know this is a characteristic of such a small subwoofer, but does the box being too small contribute to this? Can I add some polyfill to the box to 'trick' the subs into performing like the box was built to specs? If so, how much do I add?

They are powered by a Total Mobile Audio T500.1 amp running at 500W x 1 into 2 ohms. (the subwoofers are wired in parallel)

I e-mailed Pioneer technical support and this is the seemingly uneducated response:

"I have two TS-W203C 8" subwoofers in a sealed enclosure sharing a common

internal volume of 0.9 cubic feet. The subs are 4 ohm wired in parallel to an amp

delivering 500W x 1 into 2 ohm (250W RMS

per sub). This particular subwoofer requires 0.5 cubic feet of volume each. That's

a total volume requirement of 1.0 cubic feet. So, my enclosure is 0.1 cubic feet

too small. Should I add

polyfill to the enclosure to 'trick' the subs into thinking the enclosure is

bigger? If so, how much do I add?"

Pioneer's response - "Thank you for contacting Pioneer Electronics, Inc.

No, that is a wrong idea about adding a insolation. It make the box volume smaller.

You may want to have a box with two chambers. The subwoofer work well in it.

Thank You,

Khammy

Customer Service Representative

Thanks for your help.

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[Darth Audio 10+ year member]

Usually you use 1lb per cu. ft. of polyfill. So with your volume minus woofer displacement I'd suggest about 1/2-3/4 lb. When using polyfill or similar materials to stuff your enclosure you can make it 25% smaller. So your just about where you need to be.

 

[DDFrontier 10+ year member]

Thanks! That was my thought as well, but I was just looking for confirmation. 1/2 - 3/4 lb of polyfill is not going to pack this box. So, is it o.k. for it to just free float around in there? Also, the woofers fire down. Will the polyfill hurt them if it comes to rest on top of them?

Also, doesn't the manufacturer take into account woofer displacement when they state the recommended enclosure volume?

 

[Darth Audio 10+ year member]

I think your going to be surprised how much you stuff into that box if you use the whole 3/4 lb. I doubt it will be floating around. Try not to stuff right behind the woofers, but a little behind there will not hurt.

 

[briman1001 10+ year member]

So it is ok to just stuff the hell out of the box with the polyfill. I did not put that much in mine I guess. I will stuff more in there. Just stuff as much will fit is that the deal?

 

[DDFrontier 10+ year member]

No, he said add 1 lb. per cubic foot of volume.

 

[newusername 10+ year member]

This should answer your question pretty aptly:

http://www.soundsolutionsaudio.com/forum/index.php?showtopic=7168