Alternator Whine

danbrennan

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Mar 13, 1999
4,965
Brighton, MI
My '78 Z28 has an old(early 2000s) Kenwood KRC 2007 connected to a Pioneer 6200F, which is connected to the speakers and a Sound Ordnance subwoofer.

It's had annoying whine, related to engine RPM, since I installed it. So I guess alternator or spark based. I've just lived with it, but I finally decided to do something, and bought a 30 amp noise filter. But when I went to install it, I found that Kenwood had included a noise filter to their unit(and I had connected it).

So now I'm wondering if the Kenwood filter just isn't working very well, or if I need to install the new 30A noise filter on either the ignition or battery power to the 6200F? I've put chokes on my car radios in the past, and that always cleared up the engine RPM whine. So I'm a bit puzzled.

Can alternator whine come in through either the ignition or the battery line? I ran a separate 8 ga. power wire from the battery to the 6200F. I wonder if that's what needs filtering?
 

mallard

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Oct 3, 2013
2,043
SK, Canada
So that I'm understanding your question correctly, when you say "alternator whine" do you mean when you're outside the car with the hood up and there's a noticeable whine coming from the alternator itself? Or do you mean there's a whine like an "interference" sound through the sound system?
 

John Wright

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Aug 9, 2002
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Rustburg, Va
Probably need to isolate all of the power sources for all of the devices, not just the head unit...especially if there is an amplifier. Capacitors do a decent job smoothing out the power.
 

Bandit723

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Oct 1, 2016
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Waupaca WI
1654515532943.png
 

danbrennan

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Mar 13, 1999
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Brighton, MI
The whine is through the audio system. If I turn the radio off, it goes away. If I leave the radio on but turn the engine off, it goes away, too.

Just a capacitor, then? For some reason, from years ago, I thought an RF choke(inductor) was used. I wonder if I have that confused with a different problem, I do that sometimes.
 

Bandit723

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Oct 1, 2016
4,374
Waupaca WI
I also heard the noise can come rom spark plugs or wires.

Identified for letter R in the ceramic resistance. This spark plug incorporates of 3 to 7,5 k ohms (or in some cases of 1 to 2KΩ) ceramics resistance to attenuate the ignition noises generated during spark emission.
 

Jim Streib

https://www.flickr.com/photos/[email protected]/albums
Apr 6, 2004
566
Saint Louis, MO USA
Do you have the gains set properly ?.

If you can, post up the model numbers of the sub and how things are wired.

Are you also using good quality RCA's or are you running things speaker level ?.

Also double check for any speaker wires shorted to ground. Some amplifiers will still work but then might allow alternator whine to also come out through the speakers.

Possibly too there is a bad diode in the alternator allowing an AC signal to get into the DC line.

Jim
 

danbrennan

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Mar 13, 1999
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Brighton, MI
I added a ferrite bead and a 50A filter I found on Ebay to the battery power lead to the Pioneer GM 6200F amplifier, and that seems to have gotten rid of the alternator whine. Not sure I needed both, but the ferrite bead(right after the fuse) wasn't very expensive.

The Pioneer amplifier and Sound Ordnance subwoofer are mounted in the trunk.

FerriteBeadAndFilter.jpg


PioneerAmpAndSO_Subwoofer.jpg
 

mrfleet12

Veteran Member
Aug 8, 2014
1,358
West of Chicago IL
I added a ferrite bead and a 50A filter I found on Ebay to the battery power lead to the Pioneer GM 6200F amplifier, and that seems to have gotten rid of the alternator whine. Not sure I needed both, but the ferrite bead(right after the fuse) wasn't very expensive.

The Pioneer amplifier and Sound Ordnance subwoofer are mounted in the trunk.

View attachment 143287

View attachment 143286
How's that sub work, have pretty good bass?
 

danbrennan

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Mar 13, 1999
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Brighton, MI
I'm happy with it, although since I've only installed the two(I put the same one in my '74 Camaro, too), I don't have much to compare it to. I don't think it has the window rattling power some of the kids put in their cars, but I didn't want that much bass, anyway. It rounds the overall sound out well. I don't have the gain turned all the way up, maybe halfway, at most.

I don't have preamp outputs in the head unit of my '74 Camaro(like I do in my '78 Z28). I just used the line level inputs of the subwoofer there. So the bass, when playing cassettes in the ancient cassette deck, is not as pronounced. I'm guessing the bass frequencies in the speaker level outputs are just much reduced from the cassette tape, so the subwoofer doesn't have as much to work with. My point is, I found a noticeable difference using preamp outputs to feed the subwoofer, versus just using line level(speaker level) signals.
 




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