Audio Buzz

[MeMyselfandI]

Hi,

I have a 2015 M3 (F80) with an OEM Harman Kardon system. I'm experiencing a problem that I suspect is either the amp or the subwoofer.

A few months ago, I had the music up really loud. There were no problems on that trip but the next day I noticed a buzzing type sound from the center dash speaker when I played the music loudly and/or when the active sound kicked in. That sound persisted for many days without any change. In an attempt to isolate the problem, I tried turning the music up when the car was off. The same buzzing persisted. I then reduced the bass and repeated the experiment. The same problem persisted but only when the music was louder or had more bass in it.

At this point, it seems like the problem is the subwoofer. However, this is where I become confused....

I hadn't dealt with the problem and then one day a couple of weeks later it went away. No buzzing when active sound was pumping and no buzzing when I was listening to music. Fast forward a few days and I've dismissed the previous occurrence as a fluke and turned the music up. Boom... the problem returned. That was about 1.5 months ago. I've been playing the music at a more reasonable level and driving mostly in comfort 'mode' to avoid the annoying sound. Fast forward to today... I was driving down the road and someone needed to be taught a lesson in speed. I switched out of 'comfort' and hit the gas hard. No buzzing...

Now I'm confused... if the bass speaker was blown I'd expect the problem to be consistent. If it was the amp I'd expect it to be consistent and affect all types of audio including the phone (which has been fine). One thing to note... I think the evidence here is weak as there aren't enough samples but... one the day the audio problem started it was hot (high 90s) and the car had been sitting in the sun for a couple of hours before I drove it. The days it seems to have returned to normal were cooler (high 70s/low 80s). The second time the problem returned was also hot.

My working guesses are a) some type of problem with wiring/wiring connector(s) on the subwoofer; b) a heat problem associated with the amp.

I haven't pulled the speaker or amp yet. I thought I'd seek advice on what this might be and how I might go about diagnosing it without buying a new sub or amp.

Thanks!

[Kevin @ Integral Audio]

Most likely a specific speaker and not the amp. Get yourself a test tone disc and step thru from low to high. Pure tones do wonders highlighting these things.