How to Build a Sub Box for Vehicles

by Contributing Writer

If you want to put a subwoofer box in a Vehicles the chances are you'll have to build something yourself. The unique space constraints of the Vehicles cabin mean that most pre-assembled sub boxes will not fit. You can mount the box either behind the rear seat on the parcel shelf or on the floor between the rear seats and the front seats. Both have unique constraints and will fit a different size box, while one may take away passenger space.

Under The Hood:

 How to Build a Sub Box for a 3rd Generation Camaro

Measure the space in which you want to mount the box. Common places in the Camaro are behind the front seats and in the trunk.

Measure the sub you have chosen. Add two inches to the diameter and to the depth to calculate the minimum enclosure size. Calculate the volume by subtracting twice the width of the MDF from each dimension and multiplying the length by the width by the height. Compare this volume with the recommended volume suggested by the manufacturer in the documentation that came with the sub.

Adjust the dimensions until you have a box that satisfies the manufacturer's recommendations and will fit within the space you have selected in your Camaro.

Cut the pieces of the enclosure from MDF. Cut two pieces for the front and draw the outline of the subwoofer on both. Drill a hole in the middle of the material you need to remove, put the jigsaw through the hole and cut out a space for the subwoofer. Create a hole in the back panel for the terminal cup using the same method.

Assemble the box using the wood glue and screws to secure the sides together. Screw the large sides into the short sides for the most strength. Caulk the inside of all the joints with the silicon caulk for extra strength and to seal the enclosure.

Mount the terminal cup in the rear panel and secure it in place with screws. Attach the speaker wires to the terminals on the inside of the terminal cup, then run it through the box to the subwoofer. Attach the wires to the terminals on the rear of the sub and put the sub in place and secure it with the screws.

Items you will need

  • Measuring tape

  • Pencil and paper

  • Subwoofer

  • 1/2-inch MDF

  • Jigsaw

  • Drill

  • Terminal Cup

  • Screws

  • Wood glue

  • Silicon caulk

  • Speaker wire

 How to Build a Sub Box for a Dodge RAM

Measure the area behind the seats. This is the best place to mount the box, but the exact dimensions depends on whether you have a regular cab, an extended cab or a crew cab. Write down the dimensions on the paper.

Measure the sub and add 2 inches to the depth and diameter to get the minimum dimensions for your sub box.

Calculate the interior volume of the sub box by subtracting twice the width of the medium-density fibreboard (MDF) from each dimension and then multiplying the length by the width by the height. If you were using the recommended 1/2-inch MDF, you would subtract 1 inch from each dimension (2 times 1/2) before multiplying the dimensions together.

Read the documentation for the subwoofer to find out the manufacturer's recommended enclosure size. It should be listed on the documentation that came with the sub. Compare this volume to the volume of the sub box you have built and adjust the dimensions until you have a box that will fit within the space your measured in the truck and meet the recommended specifications for the subwoofer.

Cut the sides out of the MDF with the jigsaw. Cut out two pieces for the front so that they can be connected together and add strength. Draw the outline of the sub on the front pieces. Drill through the material you're going to remove, and then use the hole to put the jigsaw through and cut out the rest of the material.

Use the same method to make a hole in the back for the terminal cup. The terminal cup is a connector which has two terminals that can be permanently wired to the speaker on the inside, but can be easily connected and disconnected on the outside.

Assemble the box using the screws and wood glue to hold the sides together. Screw the long sides into the short sides. This gives the box more strength.

Caulk the inside of the box with the silicon caulk. This seals the box and gives it strength.

Put the terminal cup in place and secure it with screws. Attach the speaker wire to the inside terminals of the terminal cup. Run the speaker wire through the box and attach them to the sub. Put the sub in place and secure it with screws.

Attach the heavy-duty Velcro or similar adhesive to the underside of the box with the wood glue, and attach corresponding pieces to the carpet of the truck with fabric glue.

Run speaker wire from the amplifier in the truck to the position you are mounting the sub. You can lift the edge of the carpet and the trim with the screwdriver and hide the wire underneath.

Attach the wire to the terminal cup on the back of the speaker and put the speaker in place on the Velcro.

Items you will need

  • Measuring tape

  • Pencil and paper

  • Subwoofer

  • 1/2-inch medium-density fibreboard

  • Jigsaw

  • Drill

  • Terminal Cup

  • Screws

  • Wood glue

  • Silicon caulk

  • Speaker wire

  • Heavy-duty Velcro

  • Fabric glue

 How to Build a Sub Box for a Single Cab Truck

Adjust back the seat behind which you will place the subwoofer box. From the floor, measure how tall you want your box. At the desired height, measure the distance between the seat back and the back wall of the cab. If the last measurement is not at least 9 inches, adjust the projected height of your subwoofer down until the top is at least 9 inches wide, to accommodate at least an 8-inch speaker and a grille frame.

For any given woofer, find the published closed box volume. This volume is expressed in cubic feet or a fraction thereof. Your box size must be calculated to this volume plus the thickness of the MDF. Multiply the woofer's stated closed box volume requirement by 1,728: that is one cubic foot, or 12 by 12 by 12 inches. The speaker's size plus 1 inch is one of your outside dimensions. The inside dimension subtracts twice the MDF thickness, or 2 times 3/4 inch = 1 1/2 inches. Multiply that dimension times the inside dimension of either the desired height or the width of the box. Divide the resulting figure into 1,728 to get the remaining inside dimension. Adjust either the height or the width until you get the right volume.

On the MDF sheet, mark the outside dimensions of all six box sides. Allow for the width of the saw blade and cut. On the top panel, mark a circle large enough to match the woofer's inside flange diameter and cut with a saber saw.

Assemble the box with wood glue and screws. Drill a 1/4-inch hole in a side panel for the speaker wire. Thread speaker wire through the hole and toward the speaker hole, leaving 1 foot of wire in excess on both ends.

Split the wire 3 inches at both ends. Strip 1/4 inch at each end. Crimp on terminals to fit the speaker tabs, or leave bare for spring terminals. Connect the speaker. Stuff the box with pillow stuffing and drop in the speaker. Apply putty to the back of the speaker flange and fasten the speaker in place. Silicone seal around the wire exit hole. Connect to the amp and test.

Items you will need

  • Woofer

  • Measuring tape

  • 4- by 8-foot sheet of 3/4-inch MDF

  • Table or skill saw

  • Saber saw with rip blade

  • pencil

  • electric drill

  • Countersink drill bit

  • 1/4-inch wood bit

  • 1 1/2-inch Phillips countersink wood screws

  • Speaker wire

  • Cutting pliers

  • Wire stripper

  • Terminal crimper

  • Slip-on terminals

  • Dacron pillow stuffing

  • Wood glue

  • Seal putty

  • Silicone sealant

 How to Build a Sub Box for a Chevy Avalanche

Measure the space where you'd like to mount the sub. Record the measurements on paper.

Measure the sub you have chosen. Add two inches to the diameter and two inches to the depth in order to calculate the minimum size of the enclosure. Calculate the internal volume by subtracting twice the width of the MDF from each dimension and then multiplying the length by the width by the height. Compare this volume to the recommended volume from the sub manufacturer, which should be written on the sub's documentation.

Adjust the dimensions until the enclosure meets the recommended volume specifications and will fit in the space you measured.

Cut the sides of the box from the MDF using the jigsaw. Cut two pieces for the front. Draw the outline of the subwoofer on the front pieces. Drill a hole through the center of the outline, then put the jigsaw through the hole and cut out the rest of the piece.

Use the same method to cut a hole in the back panel for the terminal cup.

Assemble the box. Use the wood glue and screws to hold the sides together. Screw the large sides into the small sides for the strongest box. Use the silicone caulk to seal the box and to add extra strength to the joint.

Secure the terminal cup in the rear panel with the screws. Attach the speaker wire to the inside of the terminal cup and run it through the box. Connect the wire to the terminals on the back of the subwoofer. Put the subwoofer in place and secure with screws.

Items you will need

  • Measuring tape

  • Subwoofer

  • 1/2 inch thick MDF

  • Jigsaw

  • Drill

  • Terminal cup

  • Screws

  • Wood glue

  • Silicone caulk

  • Speaker wire