how much polyfill do I need to add to a box that is .85 cu ft and make it sound like it's 1.0 to 1.25 cu ft?

I've been told 1 pound per cu ft, so do I need 1 lb or 1.25 lb or do i just need .15lb-.35lb?

its not a solid answer, but i don't think you need 1 POUND of the stuff. I needed my box to be about .2 'bigger' and all i used was a generous handful. like i said, its not a real answer but i hope it helps

Generally, up to 1.5lb/ft^3 will provide benefit. Any more and it starts to have a negative effect. The stuff has a fairly minor effect, so generally the more the better up to that point. I'd say stick with a pound and distribute it evenly in the box.

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If the sub box is made to exact specs of the subs, will polyfil make it sound better? And if the sub box is a little on the large side can you just glue a piece of wood to the bottom to take up the extra airspace?

I like to use a little poly fill in all boxes unless they are too big for the sub, because I tend to like the smoother frequency response that it provides. It's really a personal preferance thing at that point though.

If a box is too big you can take up space by filling it with basically anything solid. I prefer to use more of whatever material the box is made out of so that you don't get unexpected resonances. Whatever material you choose, I suggest that you screw it to the bottom of the box. That way it can be removed later, and you don't run the risk of it coming apart. I usually like to use a little silicone inbetween to help hold it and to eliminate the possiblilties of rattles.

------------------
The IROC Homepage
<A HREF="http://www.rit.edu/~jli4307/camaro" TARGET=_blank>
View the restoration of an 85 IROC</A>
"I didn't know a bored out Ford could go so slow" -Shenandoah