Alternator Whine from Tweeters

J

Juice0517

Member
Hey all,
I have a 2009 Z4 30i and I just got it back from the shop. I put in JL Audio C5-653 3 way component speakers, an 8 inch custom JL subwoofer in the place of the storage compartment between the two seats, did a custom kenwood receiver with a custom mold since there was no kit for this model, and went with a JL XD 500 amplifier. I had new quality RCAs put in, T Spec cables. I am getting terrible whine out of the tweeters even when the receiver is totally shut off. It seems to get worse when the car moves faster like at 70 mph on the highway. Also, when listening to the music you can hear the whine behind it. My shop said they tried noise filters and a ground loop isolator which didn’t help. The RCA cables are apparently as far away from the power cables as possible. I honestly don’t know what else to do at this point. Could it be a problem with my alternator diode? Has anyone had this problem? Any suggestions and help would be appreciated.
 
Did they use the standard earth point for the Kenwood head unit that's in the loom or run a new earth so it's at the same point at the amp
 
Have you tried unplugging the sub rca cables from the amp? Id start there at least and report back

also Im amazed you fitted a different head unit, never seen it done on an e89 and Ive done a bit of research, be interested to see pics.. my thoughts are an rca issue if grounds have been checked as good and a ground loop isolator hasnt helped
 
As others have mentioned, most likely something to do with the grounding of the radio and or amplifier or the RCAs. I recently upgraded the system on my 30i with new speakers and and a 4 channel amp integrated into the car's original head unit via a LOC and it all works well no noise at all. I would go back to the shop you paid to have it installed since if they are pros they should know how to solve it. I would be interested to see how you integrated the Kenwood head unit and the sub between the seats, do you have any photos? I am soon going to be adding subs to mine.
 
Hey all. Thank you all for the replies! I really appreciate it. Yes unfortunately the shop has given up on the noise issue with me. I will try the comments suggested and report back. Here are some of the pics of the KENWOOD and JL sub install.
 

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Whatever storage sleeve that was in the middle of the seats I had taken out and then they built a custom sub box to fit in that squared space. I didn’t want the sub box going too deep to take up my trunk space because as you know it’s already limited. The sub is good it’s nothing super crazy deep bass but for the size of it, it’s plenty good sounding for my taste.
 
Overall the shop did a good job a lot of custom work was done and especially getting the KENWOOD receiver put in since there was no kit for 30i I was told. But the noise. Geez it’s so annoying. I am really hopeful something can work out. I’ve actually had the car back to the shop 3 separate times complaining about the noise and each time they’ve tried things with no success on it.
 
The sub that is mounted on the panel, is that panel flush with the trim behind the car seats? or does it protrude out a bit into the netted storage area? I assume the size of the custom sub box is basically the size of the original storage box that was there?
 
Regarding the noise if you have tried what has been suggested here and it still does not solve the problem, maybe then it is time to take it to another reputable shop and let them have a look at it?
 
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