Subwoofer inside of a Jeep Wrangler rear seat

[TerryMason]

After a year of listening to the stock speakers in my 2005 Jeep Wrangler I was ready for an upgrade. At one point I had installed a sub box behind my rear seat, but this used up the only storage space in my Jeep. After a little thought, and some internet research I found a guy who had installed a subwoofer inside of his rear seat. I decided that was for me.

This project took me several weekends to complete, as there is a lot of waiting for glue or paint to dry. The most difficult part for me was the woodworking, as my skills are lacking in this area.

I'm amazed at the final product. This box is better than I would have ever expected, and had no rattles at all. The down firing subwoofer is nice, as you don't have a speaker pointed directly at you drowning out the other speakers. The only negative I've found is that I've added about 25 lbs to an already heavy backseat, so removal is difficult. If you're into stereos, and don't want to compromise on storage space, then this is for you



Here's a video of the finished product:

 

[TerryMason]

After photos

After photos

 

[TerryMason]

Parts list
2 24x48 sheets of 3/4 MDF (medium density fiberboard)
2 tubes of Liquid Nails
1 can black spray paint
1 pint of paint for the outside of box
1 box of wood screws
1 can of rubberized undercoating / sound deadener
1 48" L bracket
1 terminal connector (best buy)
1 subwoofer (I used the Pioneer TS-SW1041D)
1 amplifier
8 Tee-nuts and bolts (purchased at Lowes)

Tool List
Grinder
Caulk gun
Drill, drill bits, and hole saw.
Several clamps
Saw (table saw makes things much easier)
Snips to cut L bracket (step 18)
Utility knife

 

[TerryMason]

First, you'll need to begin by cutting out the necessary pieces. This is about the toughest part of the whole process. You can find the cut sheet at Sirgcal's website

Once the pieces are cut You'll want to start assembly. I found the easiest way to assemble these pieces was to put some liquid nails onto one piece, then clamp the two pieces together. I would then drill a pilot hole, and use the counter sink bit to keep the screw head flush or slightly in-set into the wood (photo 3). Finally, I would screw the pieces together.

 

[TerryMason]

Initial box

This is the bottom of the box, where the subwoofer will be mounted. Once you have this bottom complete, we'll be able to test fit it into the seat frame

 

[TerryMason]

Preparing the seat

I was nervous about taking on this project - cutting up my back seat beyond repair, so I purchased another back seat for $75 from craigslist. In retrospect this probably wasn't necessary, as the project isn't that bad, but if I ever sell my Jeep, I'll put this back seat in the next one.

Here is a photo of the donor seat, and the zipper that you need to unzip to get to the internals.

 

[TerryMason]

Remove the internals

Now, you'll need to take the internals of the seat out (no big deal here), and unbolt the hardware the connects to the floor

 

[TerryMason]

Grinding the day away

Now, with your trusty grinder, remove the supports from the frame, grinding them down flush.

 

[TerryMason]

Adding the sides

This step involves alot of glue and positioning. The idea is to add the sides or wings that will support most of the weight of the box. These wings will go over the frame and support the weight of the passenger.

You can see in the photos how the box fits into the seat frame.

 

[TerryMason]

Adding to the box

Another piece on the side

 

[TerryMason]

Cutting the hole for the subwoofer

Now, using the cardboard cutout included with your sub, trace the cutout and drill holes.

Use a hole saw to start the main the main sub cutout, as well as installing your terminals.

 

[TerryMason]

Test fitting

Using a pair of vice grips, I pressed the Tee-nuts into the speaker mounts. It's a good idea to put some glue on the Tee-nut backs before pressing them in. It can be a real bear to get them into the MDF. I was then able to test fit the subwoofer into the cutout.

I would suggest that you use these tee nuts instead of screws, mainly because they are removeable (you can take your sub out if you need to). Remember that your box will experiance some significant pressure, and a screw may not hold.

 

[TerryMason]

Soundproofing

Once the bottom, side, and one half of the top are attached, and there is only one panel left, it's time for some sound proofing. I went over each joint with liquid nails again to make sure that it's airtight, then I shot the box liberally with rubberized undercoating.

 

[TerryMason]

Final panel added

After the undercoating had dried, I attached the final top panel. Here you can see the final construction of the box.

 

[TerryMason]

Bracing

With the final panel on, I was able to add the brace into the center of the box (inserted through the sub hole). This brace allows your hefty uncle to sit in the back seat, without crushing the box. It also keeps the force of the sub from expanding the box. The second shot is another round of undercoating after I had braced the box.

 

[TerryMason]

After getting the box together, I gave it two good coats of a waterproof outdoor paint. I'm sure this box will see water, so I wanted it to be well protected.

 

[TerryMason]

Weather stripping

In order to keep the frame and speaker box from rattling, I added some weather stripping.

 

[TerryMason]

Attaching to the frame

Now you'll need to attach the box to the frame. I used an L bracket, some more liquid nails (is there anything this stuff can't do?), some nuts and bolts, and more screws.

 

[TerryMason]

Mounted

Here is the box, mounted inside the frame

 

[TerryMason]

Removing the foam

I test fitted the foam cushion over the box, and used a permanent marker to outline the areas that I needed to remove. Then, just take a utility knife and cut the foam into squares and pull it out with your hands. This part was much easier than I had anticipated. I did mess up once, and just glued in some foam my my pile on the floor.

Before, during, and after photos