BMW weird noise on speakers

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I would start by looking to see if any water is leaking in the trunk or under the seats. Let the customer know to be patient as it only occurs every couple days.

I would start by seeing if it one or several speakers. A stethoscope would help. What about the mic for the handsfree? If it’s involved, covering it up should change the squeal. If more than one speaker, it is more likely to be “upstream” of the amp. I notice the radio is off. So a warning message module could be feeding the amp. Is there any known condition to cause it? Pulling fuses for the…

I like your mic idea Steve, it sounds like feed-back, like the old microphone vs. PA on an auditorium stage thing

I’m sure that the squeal is a feedback. The feedback path, output of amp back to input, is not evident though. It is unusually high pitched, indicating a short path between the input and output elements. I wondered if the actual feedback was thru a tweeter, then being broadcast by the main amp? That might be a clue to the high pitch. Or maybe it is only a tweeter that is sqealing. Do those cars…

Lastone I had had an amplifier in the drivers side trunk taking a bath from clogged drains and a water leak. If it's not too far gone, disassembly and cleaning all the green crusties off of the board will help. otherwise It's off to ebay.

I know that this is an old thread but thought I would post this as it may help someone else, this noise does seem to be emanating from the amplifier in the trunk, the problem with pulling a fuse only is it won't isolate this radio circuit correctly, as this system utilizes a M.O.S.T media oriented system transport and you must effectively bypass potentially defective components of the circuit by…