building an enclosure too small

Printed From: the12volt.com
Forum Name: Fiberglass, Fabrication, and Interiors
Forum Discription: Fiberglass Kick Panels, Subwoofer Enclosures, Plexiglas, Fabrics, Materials, Finishes, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=30197
Printed Date: July 21, 2025 at 10:52 PM

Topic: building an enclosure too small

Posted By: nyguy4u
Subject: building an enclosure too small
Date Posted: April 11, 2004 at 8:18 PM

I am almost done with the frame for my glass box. Question though, I am putting 3 15" subs in a box, all chambered off. The left and right sub is fine, but the chamber for the middle sub will be smaller then the other 2. I measured the middle space, and it's 16"D, startes off at the sub at 15"W but then as it heads towards the back of the box, ends to 9"W and 21"H. Now being that is smaller then recommended, would it be a smart idea to stuff the middle chamber with polyfill?. If so, how much?

Another question, like I said, the box will be chambered. But it's very hard to chamber with so many curves in my box. Does each chamber have to be airtight?. Or can there be a 1-2" gap near the top of the box?

Replies:

Posted By: xtreamcc
Date Posted: April 12, 2004 at 5:38 AM

Polyfill it! thats what I say anyway. Just stuff maybe half a squar foot or so, like 3 of those $2 walmart bag into it, and add/remove till it sounds right. As for the chambers, the whole purpose of chambering is to separate each subwoofer from the others to allow for independant movement, if your leaving a 1 to 2 inch gap you might as well not have a divider at all. A tip, if you only have a 1 to 2 inch gap, get some fiberglass mat, cut out oversized pieces for the gap and hot glue it to the frame, the resin over it. Add about 3-4 layers of glass to each edge and that will solve the little gap problem.

-------------
"Shiny chrome when used in conjunction with bikini models is particularly effective in inducing brain deficit disorder"

02 Jeep Grand Cherokee

Monster System on its way.

Posted By: sam1
Date Posted: April 12, 2004 at 11:57 AM

shouldnt hurt it much. id definately use polyfill tho. as for the gaps, id seal them off. like xtreamcc said, if you have a gap, you might as well not have the divider. just make sure the box isnt too small. i did that once with a set of 10s. they sounded great for 2 days until i blew the cone apart from the surround.

Posted By: kickerstang
Date Posted: April 12, 2004 at 1:17 PM

i would recomend not chambering the box. if you have 1 sub that has different airspace than the other 2 it is going to sound like a$$. just put some internal bracing and cut some good size holes in you already existing chamber walls. this will make all 3 subs have an equal amount of airspace resulting in better sound. and polyfill isn't a necessity. in my opinion it doesn't make a big difference. none of the boxes i have ever built have polyfill. find a website that has professional competitors and look at the boxes that have plexi on them, do you see any polyfill?? didn't think so

-------------
what!?!?! you want some??

Posted By: xtreamcc
Date Posted: April 12, 2004 at 1:18 PM

just another point that sam made evident, if you dont seal them off, 15's will probably blow each other apart (I mean like cones flying, voice coils frying etc) because their air displacment is like 2x that of a 10 and putting that much stress on a sub will tear it to shreads.

I lost 2 of my 3 RF's doing that, it was loud! about 130 db but it lasted about a week and has almost no sound quality, I later divided them and borrowed a friends MTX's and they were tighter hitting and alot clearer. Just some first hand stuff I think you might find interesting towards dividing posted_image

-------------
"Shiny chrome when used in conjunction with bikini models is particularly effective in inducing brain deficit disorder"

02 Jeep Grand Cherokee

Monster System on its way.