F32/F82 Full Bass Upgrade L1


Full Bass Upgrade Level One for BMW F30 3-Series Sedan, F80 M3 Sedan with 688

The speakers underneath the seats of your F30 BMW are not ‘subwoofers”, even though many folks online seem to call them that. They play a lot of middle bass notes – bass guitar, snare drums, and the fundamental vocal notes – in addition to any sub-bass they can muster. Even if you add a subwoofer, these underseat speakers really do need to keep contributing, in order to handle those critical middle bass notes. However, even after you add a subwoofer in the trunk, those underseat speakers will still be trying to play sub-bass notes – and distorting in the attempt.

That’s where Musicar Full Bass Upgrades come in. We add a sub, but we also enhance the performance of the underseat woofers in a few ways:

  • We “band-pass filter” them, taking the sub-bass notes out so that only the trunk subwoofer plays them
  • We improve the power to the underseat woofers
  • We make them “tunable” to match the rest of the system

The signal and underseat speakers are interfaced using a plug-and-play harness (no cutting) which we prep for the specific system. The signal is routed through a high-voltage-capable attenuating buffer amplifier (the H/K amplifier can reach peaks of 28 volts to the stock 8-ohm woofers, so it’s important to reduce that signal to a level which the new amplifier can handle).

Then we send the sub-bass notes to the driver in the Musicar OE-Look Subwoofer Enclosure.

  • Corner-loading gets you more output than a comparable “on-the-floor box”.
  • The “OE-Look” upholstery has been hand-dyed to match your BMW trunk
  • As a Musicar design element, the woofer is recessed 19mm from the outer edge
  • All mounting hardware and wiring is included
Level One
  • 300 watts RMS for the subwoofer
  • 50 watts per underseat stock woofer
  • active crossover filters preset for the woofer/subwoofer “handoff”
  • plug-in integration harness prewired to high-voltage attenuator
  • loaded enclosure with 10-inch high-fidelity  subwoofer



Application Notes

This package does not fit the F30 sedan, F34 3-Series GT, F33/83 convertible, or the F31 touring. It is for F32 and F82 coupes  688 H/K audio systems (if you have 676 HiFi, contact us, thanks!)

The installation is plug-and-play to the HK amplifier, and our equipment rack bolts into existing trunk holes. The turn-on wire requires a single connection, without cutting. There are two holes to drill out of sight for wire passage – they are very hard to find afterwards. For these reasons, we recommend professional installation of the Full Bass Upgrade.

The enclosure mounts with a single bolt through the inside of the enclosure, to a receiver we provide which bolts to an existing bracket.

Our harness includes a center-delete loop, which allows you to easily test our recommended “surround off, center delete” setup for the H/K audio package.

The Level One package sends 300 watts of continuous RMS power to a high-fidelity 10-inch subwoofer with integrated grille. The underseat woofers receive about 50 watts each of “band-passed” power.


Additional information

Level One

300 watts for the subwoofer and around 50 watts per underseat woofer