Mod Description
Mod Details
PremiumNo Difficulty






This is the 451 underseat bass box, it is available from smart (part A4518200302 for RHD) for a price of £125 at the time of writing, although smart part prices change almost daily.A better idea is to buy one second hand from someone who is upgrading.
Remember to get the correct one for your car depending if you have an RHD or LHD smart.

This shows the underside, you can see the speaker and the sound port.

Remove the driver’s side seat, run the wiring and place the bass box in position.

Amplifier Chip
Emmanuel N thought his amplifier chip had failed so took his bass box apart and sent a photo for the reference number.

TDA8563Q is a 25W amplifier chip attached to a massive heatsink. It’s unlikely to fail but if it does, they are easily available.