I originally planned to use a single Infinity 10VQ 10″ sub, in a partial fiberglass enclosure using only half of the rear cabin floor. Since I had plenty of power to work with, I decided to go with two 10VQ’s. My measurements said it’d be tight, later I decided it would be too tight. So I sold the Infinitys and went with two SoundSplinter rl-10. These subs had good reviews and a more manageable mounting depth. These are dual 4Ω voice coils, and would be wired for a total 4Ω load, or about 425w RMS to each. This would be the third sub box I’ve built for the Titan. You can see my other boxes here: Sub Box I and Sub Box II
My first design was to downfire the subs, but this would have proved very difficult to do, so I scratched that and went with a more traditional approach. Each sub would have its own seperate air-space, of about .72 ft^3 or so. A length of 10ga speaker wire would run through the center divide to connect the two speakers to a single terminal cup. I originally planned to paint the enclosure using Duplicolor’s spray-on bed liner. That turned out to be a bad idea. The spray on bed liner turned to a tar-like goo that I eventually had to scrap off, totally ruining the hours and hours of primer, sanding, and body filler I had put into this box. So in the end I carpeted the box in the same manner I had with the other two boxes. I suppose pictures are better than words, so here you go:
This is the very beginning. I basically designed and redesigned as I built, test fitting as I went along.
The small strip of wood laying next to the incomplete box was added to give the box a little more length that I originally hadn’t designed for. You can also see the two holes cut out of the bottom of the box to allow for a little more clearance on the bottom of the subs.
Here you can see the chop mat fiberglass. This helped increase the mounting depth by approximately 1/2″. I used aluminum foil underneath the hole to keep the resin in. I also made a series of cuts into the edge of the hole to allow the epoxy to seep into the wood.
In this picture you can clearly see the two layers of MDF on the rear of the enclosure. If you look at the bottom of the “U” you’ll see where I used a router to remove about a 1/4″ of material from the bottom of the box. I did this because the box was resting too much on the transmission hump.
Here’s the box completed except for the top. I used caulk to help seal off the enclosure. You can also see the small wedges used as bracing along the top. Just like my Sub Box II, this box includes a 3/4″ lip along the forward edge so that the floor mats fit neatly underneath it.
In order to have the subs sit flush with the top of the box, I had to make their mounting surface 1″ below the top. To do this I built a router jig, so that I could remove 1/4″ of material from the MDF rings.
This is a test fit of the MDF rings. You can see where the material was removed from the center portion of the rings.
Here are the rings mounted to the top board. I used 4 3/4″ fine thread dry wall screws on each ring and carpenter’s glue to secure the rings. Then a layer of epoxy and fiberglass was added to the edges to strenghten the spots made thin by the router. The subs would be secured using 8-32 x 1″ allen head bolts and T-nuts. I had to grind off the edges of the T-nuts for clearance between the sub basket.
This is after the 1st coat of primer. Because I was originally planning to paint the box, I had counter-sunk all the screws, then filled all the holes. I also used a 1/4″ round-over router bit to give all the external edges a clean look. After 3 coats of primer and a little body filler it was looking good.
After the disaster with the spray on bed-liner, I decided to carpet the box. Rounding the edges helped the look, as well as the flush mounted subs. It took me several tries to mount the subs, since I kept knocking the T-nuts out. Eventually I used a dab of super glue to keep them in place. With everything cranked down, the box sealed up perfectly.
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