How to Treat the Inside of a Built-in Cabinet for a Subwoofer

Cut a piece of scrap carpet the same size as the bottom of the cabinet or shelf where the subwoofer will rest. The piece of carpet should be a snug fit within the cabinet so it doesn’t move around when you install the subwoofer or make changes to your audio settings. You do not have to glue the scrap carpet to the cabinet if it is cut to the appropriate size.

Cut a piece of closed-cell foam to fit the top of the cabinet above your subwoofer. Stick the piece of closed-cell foam in place with an appropriate spray adhesive. Allow the adhesive to dry according to the manufacturer’s instructions before moving on to the next step.

Measure the back of the inside back portion of the cabinet and cut another piece of closed-cell foam to fit that area. Using your spray adhesive, stick the section of closed-cell foam in place. Allow it to dry as recommended.

Cut the foam on the back portion of the cabinet where cabling runs through and out of the cabinet. You can do this by locating the hole on the back of the cabinet with one hand and making a small incision in the foam. After the incision is made, cut around the hole with a pair of scissors or a matte knife so cabling can run through.

Measure and cut foam to fit both sides of the cabinet. Secure the foam in place using the spray adhesive. Allow the glue to dry as recommended by the manufacturer.

Put the subwoofer in the cabinet on top of the scrap carpet. Connect the subwoofer to any audio cabling you are using and test the subwoofer to make sure it is working properly.