Car Audio Alternator Whine, new head unit

Stereo, security systems, vehicle electronics, and electrical-related discussions
Post Reply
Posts: 1
Joined: Mon May 08, 2023 12:12 pm

Car Audio Alternator Whine, new head unit

Post by wjblevins »

I have a 2007 Pontiac Vibe that I bought used last year. The car had an aftermarket head unit and used the existing amp and speakers. There was no alternator whine. I installed a new head unit. That is the only thing I changed. There is now an audible alternator whine. I assume it is a ground loop. I've tested my HU ground and it looks good. I also tried grounding the HU directly to the battery. The whine continued.

I have yet to find any information about this problem when the stock amp and speakers are used. Everything discusses RCA cables, which I don't have. Could it still be the ground for the amp even though I haven't done anything to it and it wasn't there before?

I've played with all of the connections from the HU to the wiring harness. Nothing seems to make it go away. I don't know what else to do about the ground loop if my ground seems to be good.

I have read lots of proposed solutions but most don't seem to relate to my situation and those that do haven't solved the problem. Could there be a problem with the ground inside of the head unit itself?

Edit: Just to be clear, I've read tons of posts here and watched tons of videos elsewhere. I know there are a lot out there.
User avatar
Posts: 9882
Joined: Fri Mar 21, 2003 5:19 am
Location: SMC MD

Re: Car Audio Alternator Whine, new head unit

Post by joatmon »

welcome to genvibe!

odd that it would pop up when only replacing the head unit. Perhaps the new one is more noise sensitive than the previous one. If the noise is coming in the power line, you might try wrapping the power wires around a ferrite core, or putting a capacitor between the power leads, close to the head unit.

crutchfield has some tips on identifying the source of the noise at ... guide.html

sorry to not be of more help, but if you get it fixed, let us know how
Posts: 57
Joined: Mon May 23, 2022 2:50 pm

Re: Car Audio Alternator Whine, new head unit

Post by chromelampshade »

I have came across the same issue when I replaced my unit with the ILX W650

It seems like the problem lays either in between headunit, or factory amp. I also noticed the noise I personally have is ONLY carried through the rear channels. So what im thinking is, there might be some sort of correlation between hi level current & the factory amplifier.

Here pretty soon I am going to entirely get rid of the factory amp and replace with a after market 4ch, rewiring each speaker, and utilizing low level input (RCA out) from headunit. It will be much easier to dial in the source of the ground loop.

Might I also mention, after years of doing car audio on this vibe. I have came to realization that the factory amp provided IS NOT a good option to utilize. The wiring is overcomplicated and makes installing aftermarket headunits a challenge, as you have to know exactly what wire is for what. Factory amp has leads for remote turn on, mute function, power antenna, etc... just junk the factory amp entirely for a decent 4ch with sufficient power @4ohm.

You'll then be able to dial down the source of the noise, headunit ground, amp ground, other grounds etc..

I believe if you utilize low level signal (RCA OUT) for sub amp and or door amp, less noise will be carried through as the RCAs are shielded, etc.
Remember, ground loop is the number one killer for sound quality car audio builds, its so common and difficult to pinpoint, ever case is different with every vehicle.

As someone else mentioned above, you can use noise filters inline to prevent this, but if im not mistaken it comes with some disadvantages, you'll have to research more on it. But me personally, I just play the music loud enough to the point where I dont even hear the wine anymore haha.

EDIT: I've even tried to dedicated ground like you have, but it did not solve it, 50% certain problem lays in the factory amp, probably has horrible noise filtering.
2003 Pontiac Vibe AWD Base "Bass Mobile"
320A Autotech Engineering Alternator
1/0 Oversize Sky High "Big 4"
Optima Yellow Top 55aH AGM
B2 Audio Rage 2500.1D V2 > DDX 10
6th order bandpass series tuned 27/50hz
Posts: 1126
Joined: Mon Jun 05, 2006 4:02 pm
Location: Seattle, WA

Re: Car Audio Alternator Whine, new head unit

Post by SeattleJeremy »

Same thing happened when I installed amps in my car. It need inline isolators.
*Sold* 06' Vibe Base - Mono Platinum - Manual
15' BMW 328i Sport - Jet Black - Auto
Post Reply