Dynavin alternator whine, help diagnosing
 

Hey guys,

I just recently installed the Dynavin head unit (replaced stock nav and DSP amp).

Setup:
'03 X5 4.4i
Dynavin head unit
Alpine 5 channel amp
Passive crossovers

I currently have an alternator whine (high pitch whine with rpm rise; revving the engine or accelerating during normal driving).

I've tried everything I can think of and researched on the internet; I'm out of ideas =(

1. made sure all unused plugs taped up with electrical tape
2. toggled the "Brake" option in the Dynavin settings menu
3. grounded the "Park" wire on the Fakra cable
4. grounded the Fakra ground cable (black wire) directly to a metal piece in the vehicle (also tried grounding to the same bolt as the amp's ground wire)
5. adjusted the gain down on the aftermarket amp (helps make it less obvious, but still there)
6. pulled all the RCA cables (Streetwires twisted pair) from under the carpet floor and had it running straight through the interior cabin from the head unit to the amp
7. installed a ground loop isolator (also helps make it less obvious, but still there)
8. cut the amp ground cable to the bare minimum
9. used a dremel to sand down the contact point where I bolted the amp ground cable to a medal piece in the vehicle
10. installed a power line filter on the yellow wire of the Fakra cable closest to the plug into the head unit
11. cut all of the FL/FR/RL/RR audio cable line outs in the Fakra and taped them up individually (using RCA output only)
12. used the shorter harness to connect the head unit directly in the trunk and running a short regular RCA to the amp

I had the head unit and amp on and RCA wires disconnected = no alternator whine. Plugged the RCA cable to the amp, but disconnected from the head unit, amp and head unit turned on = no alternator whine. Plugged the RCA cable into the head unit and head unit and amp turned on = yes alternator whine.

At this point, I am pretty sure I can rule out the passive crossovers, Alpine amp, RCA wires, and Fakra cable. Unless there's anything else I can try, the only thing left is the Dynavin head unit (head unit itself, or all the RCA output plugs). Do you think it could be a problem with the Dynavin unit itself?

Anyone know where's a good grounding point in the front dash area? It seems to be mostly all plastic. There is the metal tubing behind there, is it safe to use a self-tapping screw to make a ground point on those metal tubing?

Thinking of grounding everything to it: tapping into the Fakra ground wire, Dynavin chassis, and the power line filter

You need to put a filter inline somewhere? Maybe even a couple. Have the shop that looked at your X suggest the location?

Hey Mike,
Thanks for taking the time out to show me the Android version of Dynavin...really appreciate it. Sorry that I couldn't be of help with your alternator whine noises :(

I assume you are using shielded RCA cables, next I would use a different ground for the radio. i would run a new ground wire for the radio and terminate at the grounding post you used for your amp.

How To - Car Stereo - In Pursuit of a Noise-Free System: The Ten Commandments of Noise Prevention

I'm using StreetWires Zero Noise 5 RCA cables (twisted-pair). I'm pretty sure it's not coming from the RCA cables because I completely pulled the RCA cables out and ran it straight back to the amp through the interior cabin and it still had the same problem. Also tried regular RCA cables (when I tested with the shorter harness plug where I relocated the head unit in the trunk for testing).

At this point, I'm pretty sure it's a grounding issue with the head unit. The problem is that the ground wire is tied into the Fakra cable. So that means that it's running from the front all the way to trunk (~18 feet). Wonder if this length is too susceptible to noise being picked up? I've tried cutting the ground cable at the Fakra harness in the trunk and re-routing it to the chassis and also to the amp's grounding post without much success.

I'm wonder if the ground wire run is just too long? Should I try to cut the ground cable at the head unit harness' end and grounding it somewhere up front? I can't seem to find a good place upfront to ground to. Any suggestions on a good grounding point up front? I don't know what those metal pipes are behind the dash where the head unit slides into.

OK, finally fixed the alternator whine noise issue!!!

Installed a high/low converter on the output speaker wires and removed the output RCA plugs. That fixed everything. Perhaps the output RCA is somehow picking up the interference from the speaker wires on the Fakra cable.

So after trying ground loop isolators, power line filters, and high/low converter...I could've applied all that towards an AudioControl LC6i.

Oh well, next time. I'm just happy the alternator whine is gone and I can move on to upgrading the subwoofer to finish up the project

Nice! :thumbup:
Gotta update the other DIY thread! ;)

Yup. Already did, with additional pics.

I think if I had to do it all over again, I would consider going the AudioControl LOC route and just split out the speaker wires from the Fakra cable in the left trunk compartment. Not that much more complex, and you don't have to run the RCA cables so long through the cabin floor. Plus you get another piece of equipment to play with =D