I am fitting a new soundsystem in my bmw (e46). There's an amplifier in the boot (mb quart onx 4.80/500). A line out converter converts the high level inputs from the OEM headunit, into the low level inputs required for the amp. And a bluetooth module (GROM BT-3) which acts as a CD changer.
Setup: Bluetooth -> Headunit -> Line Out Converter -> Amplifier -> Speakers
Everything is great when I am using the CD player in the Headunit. No interference what so ever.
But when I use my bluetooth module for playing music, there is so much interference. A constant static sound which increases in volume as I turn up the volume on the headunit, with/without the engine being on.
It's clear my bluetooth module is causing the interference, but how can I get rid it and still use bluetooth?
Note: I had another OEM bluetooth module(hands free) installed in the car, that was also giving me similar interference and I have removed that which helped a bit. I have also tried moving the module from the boot, into the front of the car away from the amp. It made no difference. Using a different device connected to the bluetooth makes no difference either.