Features

Mounting: The ISUB BMW 4 is a direct replacement for the factory under-seat subwoofers in select BMW models. In most cases, the new sub has the same screw hole pattern as the factory sub and is a perfect fit, but there are a few instances where the factory sub was glued in place and new screw holes need to be drilled in the plastic factory enclosure. The factory grille is re-installed over the new subwoofer. This sub is packaged individually, so you will need to purchase two. Please enter your vehicle information to confirm fit.

Wiring: The BMW factory wiring harness plugs directly into the subwoofer frame.

Polyglass Cone: The subwoofer cone has a cellulose pulp base and is coated with a uniform deposit of hollow glass microballs. The addition of the Polyglass layer significantly increases the cone's rigidity without adding much weight. This combination takes advantage of the accuracy and neutrality of the hard outer surface, but maintains the superior damping characteristics of the cellulose pulp. The subwoofer has a built-in cover, so the cone isn't visible during installation.

Magnets: The sub uses a neodymium magnet to minimize size without giving up magnetic field strength.

Reinstalling Seats: When researching a previous generation BMW replacement subwoofer, I found a warning about not reconnecting the battery until the seats have been reinstalled and the wiring reconnected. The warning stated that reconnecting power too soon, to test the new subs, can damage the seats and airbags. I found no such warning related to this ISUB BMW 4 sub, but to be safe I recommend heeding the warning in this case as well.