[apexxx6789]

Hooked up a JL 500/1 amp and a polk audio sub using the Technic Logic7/HK (677/688) add-a-sub harness. Set my sensitivity using 50hz and played a bass heavy song. Lost all bass to include stock subwoofers.

Audio is still present, has anyone experienced this?

[Jay0Hx]

I had a similar issue in my 335D E92. I lost ALL bass after installing an apple-car play unit and after some research it was due to how the car passes audio around.

For me it was because the car play unit was using the AUX input as its main audio feed and the AUX quality is AWFUL. I swapped out to a Mr12Volt which uses the CD/FibreOptics as the main audio feed and that solved my issue.

You may have a similar issue depending on which audio system you have in your car and how you've wired your amp and sub in?

[apexxx6789]

I do have a basic car play unit, none android that only works off the phone. No issues since install a year or 2 ago.

Had intermittent SOS/MOST issues that were resolved a couple weeks back for no audio. Since i had trunk covers off, decided to install technic harness, rca out off of logic 7 amp inputs, with equipment laying around.

Initially durint install with very low rca input settings i blew my main fuse to JL amp. Replaced fuse and everything was fine. Adjusted sensitivity settings per JL manual, ran a bass song for a minute or 2 and all bass turned off. Still have audio, just no bass.

JL amp turns on, aftermarket speaker is not blown, no voltage at rca inputs.

Dont know if i blew the logic 7 amp or not.
Have not looked for stock radio fusses yet, but figured if i blew the stock amp i would have no audio... havent messed with sound systems in yrs and not bmw.

I guess will see, waiting on a bass knob since it was pounding lol