I've been looking over the wide variety of DIY subwoofer enclosures posted in this forum and I'm thinking that my best bet would be something similar to bonz's setup posted in the subwoofer thread (see attached pics). Unfortunately I can't seem to find dimensions anywhere, and I'm at my wits end trying to figure out how to make everything fit.

Here's my situation. I'm trying to keep this project as low budget as possible. I already have a 12" Infinity Kappa Perfect Sub (Stats here,) and I have cannibalized the sub box from my previous vehicle as it was way too big to fit in the R50. This gives me plenty of 3/4" mdf to reuse. The sub is powered by a Premier GM-7150M mono amp. This leaves me with everything I should need, but no real idea how to make it fit.

Any help would be greatly appreciated.

 

Details:

• 12" 4-ohm subwoofer
• aluminum cone with high-roll butyl-rubber surround
• massive cast-aluminum basket
• suitable for free-air use (handles up to 175 watts in free-air applications)
• power range: 75-350 watts RMS (1,400 watts peak power)
• frequency response: 18-200 Hz
• sensitivity: 96 dB
• top mount depth: 6-1/8"
• sealed box volume: 1.0 cu. ft.
• ported box volume: 1.75 cu. ft.

Seems like you just need to get a measuring tape and get started. Begin with the base of the box, that is the most constrained dimension. Just measure your trunk space to get this.

Next consider the top-mount depth, 6 1/8". Then consider the overall enclosure volume, 1 cubic foot. Width x Depth x Height = enclosure volume. Remember to take into account the thickness of the MDF, you want 1 cubic foot of air inside the box, which is 12" x 12" x 12". You probably won't be able to make a cube box, but this gives you a rough estimate of what to shoot for. It doesn't have to be exact, just close.

Also, remember that your battery is back there, so you need a way to still access it in case of emergencies. I would just put extra wire to your sub and amp so you can move them onto your back seats if you need to access the battery. The amp can go wherever you want it, just keep it stabilized and in a place that can breathe.

Good luck.

 

Thanks for the encouragement, though I should have specified. I drive a 2004 R50 so my battery is actually under the bonnet, so I suppose I'll just have to run the wires a bit further.

I haven't had a chance to muck around with it this week, school managed to eat up all of my free time. However, now that the weekend is here I'll get out the measuring tape and try to mock something up out of cardboard. Hopefully I'll have the presence of mind to snap a few photos of the process.

 

Sadly, I'm several weeks in and still no real progress thanks to school, but with finals week at hand I might actually have a moment or two of spare time. Here's my question: I don't want to lose half of the boot to a sub box, which appears to be what would happen should I go with a square or rectangular box. However, if I go with a design similar to to the picture I first posted, according to the sub box calculators I've looked at online the internal volume would only be .61cu/ft. This is obviously well short of the 1cu/ft that the sub calls for. Is it still advisable to go this route? Would stuffing the box with polyfill make up for this?

 

Polyfil does act to increase the volume of your enclosure, but I don't know how much. 0.61 is a far stretch from 1.0, and it won't sound as good and could possibly damage the sub. Try to do some research on car audio forums and find out about the polyfil.

 

The car audio forums is where I came across the idea of using Polyfill. If what I've read is correct, using polyfill can make the sub believe it's in a box up to 40% larger than it really is, though all of the examples I can find are for enclosures larger than 1cu/ft. The 40% figure is what got me thinking,

http://www.audiojunkies.com/blog/134...osure-resource

I still have reservations about building an enclosure that's slightly more than half the recommended size, and I wanted to check with a more knowledgeable source before I committed to anything. If you think that it could damage the sub, then it looks like I'm back to the drawing board.

 

I don't know if you're still around, or if you've already built a box yet, but if I were you, I wouldn't use polyfil unless you know the exact dimensions of the box you want to build first. Also, here's a little tip. Your magic number when building a box is 1728. To figure out cubic airspace, you need to multiply LxWxH then divide by 1728. Don't forget that because you will be using 3/4" MDF, you need to make the box so the interior cubic airspace is correct. So if the cubic airspace is 12 x 12 x 12 then your actual outside dimensions will be 13 1/2"

 

My battery is in the trunk I also have 2 1000w 12" Bose Phantoms shallows, 1200w Planet audio 1200.2 Bridged and running parallel, I cheaped out with the desired board to use and went with interior/exterior 3/4" Ply reason being I have or had 3 sheets lying around unused I am also on a low budget. I just used up my entire trunk space with the 2 Subs in one box. I now have a bigger dilemma though my system is causing too much draw from the alt and battery looking for a location to place a secondary battery most likely gonna use the back floor boards for now till I can come up with a more perm solution

 

Adding another battery won't solve the issue of too much draw. You'll need to upgrade the alternator or turn the volume down. The extra battery will only extend the listening experience before the inevitable occurs, which is a battery too weak to start the car. On top of that it is very hard on the alternator when you draw a battery down like that and then expect the stock alt to charge it as well as power the car's regular electronics.

 

I have sorted out the power issue and since my post above I have upgraded my subs and amp 2 times
currently have a 3k wats mono block amp, and went to just 1 sub 12" 4k watts, as for power draw very rarely have any issues after I installed the 8.8 farid capacitor.
yes there is a but here also
I do have an issue with my hu cutting off while driving I feel it is to do with the safe driving volume control of the factory hu so I am swapping it out with an after market one that has BT steering control capabilities review cam and can play mp5.
If the cutting out persists then I am not sure what it could be