Installer Institute: Custom Sub Box

For a few years now it has been a trend for subwoofer manufactures to create huge monster subwoofer that require a crazy amount of power and can take up your entire trunk. I guess those of us that don’t have trunks are out of luck that is unless we remove one of our rear seats and drop in a square MDF box. Well I don’t know about you guys but that is not an option for me so I was glad that manufactures heard our cries and recreated a quality shallow mount woofer. In this article we will be taking you though a step by step of building an enclosure for a 2007 Nissan Frontier 4 door truck. This enclosure will be constructed completely out of fiberglass not wood was used in the final product. This build took a total of 10 hours to build and have a material cost of $65.00.

Step 1 The storage bin was removed from underneath that rear passenger seat and the Pioneer TS-SW251 was set into place to check the clearance between the sub and the bottom of the seat.

Step 2 2” masking tape was applied to the entire area to help protect the carpet. We applied some red electrical tape so the reader came see the outline of what the base of the enclosure will be. Once we had the outline we cut 5 layers of 1 ½ oz fiberglass mat.

Step 3 Aluminum foil was then applied over the tape, it was attached with 3M super 77 spray glue. When using this technique you should apply 2 layers of foil, this will make it much easier to separate from the floor when you are ready to remove it. Fiberglass resin was mixed up and applied to one layer at a time. After each layer you should roll any air bubbles out with a fiberglass roller.

Step 4 With the glass dry we popped the base out and begin to shape it. First, remove all the foil and retrace our line, then a jig saw was used to trim edges smooth. Next a speaker ring was made and the base and ring were set back into the vehicle to check the available height. Wooden supports were set into place and the seat was dropped again for a final check.

Step 5 With the supports made the next step was to tape up the top of the base and create a wall of tape around the edges of the part. Once completed the ring was super glued into place on top of the tape. 2 part expanding foam was mixed up and poured into the taped area. Special note: using a cheap blender to mix up the 2 part foam will give the foam even consistency throughout the entire project. Once the foam dried it was cut and roughly shaped with a hacksaw blade and a grinder.

Step 6 With the shape rough the project was sanded flat by hand and then set back into the vehicle for another test fit. When everything checked out we started to reshape the panel to give it some unique contours. With the final shape decided on the panel was covered with aluminum foil, then mold release wax and prepped for fiberglass.