HK subwoofer box - hack to fix the buzz from it

Psifire

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Joined
Aug 1, 2025
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3
Hi,

I've been looking around to see if anyone else tried the same solution to fix the buzz coming from the behind the head HK subwoofer box in the Z3. I don't see this anywhere; so, sorry if this has been mentioned before.

Anyway, the issue with the HK subwoofer box is that the plastic box is attached to a metal frame via 4 metal screws. This plastic-on-metal configuration is just poor engineering as it looks like no one at BMW ever tested the radio at high volume.

So, the solution I used? Weather stripping

Unscrew the box. Put weather stripping around and across the screw hole. Reattach the sub with the screws, but _do not_ torque it all the way down. What you're making is a grommet so that your subwoofer "floats" above the metal brackets.

Does this effect the sound? Probably. The alternatives are to live with the sound, to get someone to build a new subwoofer, or to get a commercial sub that will take up trunk space. My vote is for the weather stripping. :cool:

Thoughts?

Psifire
 
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