Just a few question's I have built a sealed box in fiberglass for the rear trunk recess in my car. I have a huge amount of air space. If fact I have not even measured it yet but the estimate is 24*16*16. or 6144 in ^2 or i think ~3.5 cubic feet of air space. My little 8w0's only want about 1/15 of that to run correctly in the sealed box. Minus the sub space of course.


So my question is this. I can step up to dual 12's in the box I have built but can this space handle that sort of speakers. For the time being can I fill the box with 2X4's or the like to decrease the space or am I simply stuck. someone once suggested filling the box with polyfill but I believe that it will cause the oppisite effect and make the box seem larger to the sub. Or can I port it and get a little more sound out of the speakers I have now.

I am pushing about 200 or so true to the subs that I have now and need some suggestions on 12's If you got them .

 

I think 3.5 cubic feet is a bit on the optimistic side. My fiberglass enclosure took up the entire trunk well (including the space used by the tools) and was just over 1 cubic foot. 1-1.5 cubic feet is more realistic.

The amount of space back there is well suited to a pair of 8s, 10s, or a single 12. But IMHO 8's (especially W0s) don't really have the oomph to penetrate into the cabin so I recommend 10s or a 12.

If you want to get precise, find out the exact internal volume of your box by pouring a measured amount of water into it. Once you know this, get the Thiele/Small parameters for whatever subwoofers you're considering, and plug it all in to a subwoofer design program like Blaubox.

A pair of JL Audio 10W3 subs receiving at least 500 watts RMS is a known-good arrangement.

Random thought:
You might be able to get good results by dividing your enclosure into two separate ported boxes, each holding an 8" sub. I've had good results with 8" JL subs in .5-.6 cubic foot ported enclosures - but - haven't tried it in the S2K so I don't know if it would be enough.

Good luck!

 

Maybe I did my calculations wrong but I thought that was on the high side as well. I have the e3xact same size box as you. I can't get two 12's in for the life of me, I can get to 10's in easy. with what you are saying as the true box volume then I should simply be able to go to the 10w3 or comparable sub and keep the box as it stands. I don't get any penatration through the cabin above 55 or so and very little with the trunk down but when you open it up I get huge nice tight bass. So I guess it's off to go find some used 10w3's to play around with.

 

i got 1 12" in my trunk and it takes up all that space includin the tool part but dont get w0's man atleast w3's if ur gonna go with jl and if u got a little more money go with diamond m6's theyre so much nicer i got the 12" diamond m6 with an autoteck 1200 watt amp goin to it and a pioneer 9400 head unit and im lovin it