Can someone help me with alternator whine?

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Hi everyone.

I have done some forum searches, and searches on the net, and found lots of cures to this annoying problem. I am really confused and was hoping one of you could give me some clues as to what is causing my alternator whine. It is pretty loud, and very annoying. Along with the whine, I do get a hiss, and even some spark plug ticking. Yes I get it all! I don't know what to do!

Here is a short example of my setup, in my Lincoln LS:

Electrical components:
Stock radio system, running to a passive line out converter, 1 set of RCAs from that run to a Kenwood Graphic EQ, three sets of RCAs come off that, 1 goes directly to the SUB AMP, and two go to the Crossover. From the Crossover the RCAS go to the FRONT AMP, and the two BACK AMPS.

Wiring:
Battery is in the trunk. Two short 4 gauge wires + and - run off the battery to the + and - power distribution blocks and from there 10 gauge wires run to the amps. The remote turn on is a 20 gauge wire running off of some power wire I found behind the stock stereo. It splits off into 6 components to turn them all on.

All RCAS are nice Phoenix gold shielded cables, all power wires are run away from the RCAS. All components except for the head unit share the same positive and negative connections, off of those two power distribution blocks. The only thing that has it's own power is the head unit, because it comes off the wiring harness of the car, since its stock.

Any clues? I was going to try to eliminate components by using loopbacks to see if I can figure out where its coming in. I know it could be a ground loop, but everything is powered off two 4gauge cables coming straight off the battery and going to the blocks.

What could I try next? I thank anyone who had the patience to read through all this and answer my question. Thanks,

...Tim
 
I honestly don't know why, but alternator whine is usually a consequence of ground loops. I would suggest ripping it all apart and starting fresh...

Amps to speakers only, no input. Got whine?
Add crossover, no eq unit. Got whine?
Add eq, no LLC's. Test again...
Add LLC connection from HU. Test again.

You'll probably find that adding either the crossover or eq unit makes the noise come back. Evaluate your options from there.
 
Concerning Grounds

Concerning grounds,

I run a 4gauge wire off the battery and then branch that off to a bunch of 10 gauge wires going to the amps. do you think it would be better if I didn't run the 4gauge, and took the 10gauge wires right to the battery on their own?

A reason I am probably getting whine is because my head unit is powered from wires off the harness, while everything in the back of the car is powered using fat gauge wires, connected right to the battery -.

If this is the case, do I need to get a ground loop isolater to cancel out this?

Thanks for all the help guys! I will try the eliminate components troubleshooting technique when I get some time, thanks!

...Tim
 
Either you get alternator whine or not, all your devices should be grounded exactly to the same point. Cut the ground wire that is attached to your head unit, and pass a new grounding wire from your head unit to the point the rest of the devices get grounded.
Good luck
 
Don't use a ground loop isolator unless you really can't find the source. Think of it as a bandaid. Is the whine always there or does it only come on once in a while? If it's always there it's almost certainly a grounding issue. If it comes on only say when you're air conditioning or headlights are on, then it could be you just need to reroute your signal cables.
 
Always

It is always on. Every component in the entire system is grounded to the same point, except for the stock head unit, which is obviously grounded to the stock wire harness, and probably the shell of the radio is grounded to all the metal that it is screwed into. Since that is the case, I would have no idea how to isolate it.

I will have to run some tests, to narrow down what device could be introducing the noise into the system.

What a pain in the ***!!!! Thanks for the help guys,

...Tim
 
If you were keen enough (or desperate enough) you could always open up the alternator and put RC snubbers across the diodes. Also, a small inductor and then a filter cap on the output, just like in a normal mains transformer power supply.

With an alternator the 3-phase rectified output has in theory about 2% ripple if the stator winding was a pure sinewave. The only one I ever looked at had a slightly flat-topped waveform which was good from the point of view of ripple.

BTW, do you have a nice short, *thick* cable from the engine block to the car body?
 
At my previous post, I forgot to mention something important. Alternator whine has two basic causes:

1) Ground loops.
2) Electromagnetic interference from the power cables to the rca (low level signal) cables.

To avoid ground loops, ALL devices should be grounded to the same point.

To avoid e/m interferences, the cables that give power to your amplifier, shoud be as far as possible from the RCA cables, no matter if your RCA cables have good shielding or not. The best technique, is to pass the power cables from the left side of your car to the amplifier, and the the rca cables from the right side of the car, to the amplifier.

:)
 
This may sound strange

This may sound strange, but when I was routing my speaker wires from the front doors of the car, back to the amps in the back, I could hear alternator whine in the speakers, and the speaker wires weren't even plugged into the amp yet.

Is it possible that it was pulling the noise right throught he wire, and playing it through the speaker, without the speaker wire even being plugged into anything? Kind of an induced noise problem?

My battery is in the trunk. I haven't added any ground wires from my engine block to the chassis, but maybe I will try that, see what happens.

...Tim
 
I got the same problem =(
I had different head units in my car before and didn't have the alternator noise...and now I got the new radio and I got some really nasty alternator noise...
I tried everything and nothing seems to work...
Should I try getting the noise filter? and if I do would it decrease the quality of the sound?
Or should I try running both the positive and negative wires straight from the battery? would that help?
Someone please help...
 
It is kinda controversial in the car audio world, but I like to run all my component grounds back to the battery. It may be redundent, but it got rid of my whine. Some cars have the chassis spot-welded together and it increases the chassis resistance at the back of the vehicle making the system suseptable to ground-loops.
 
Re: This may sound strange

Timbers said:
This may sound strange, but when I was routing my speaker wires from the front doors of the car, back to the amps in the back, I could hear alternator whine in the speakers, and the speaker wires weren't even plugged into the amp yet.

Is it possible that it was pulling the noise right throught he wire, and playing it through the speaker, without the speaker wire even being plugged into anything? Kind of an induced noise problem?


Were the RCA's connected to the HU? Are you running the RCA's next to the power cables? Your long RCA will end up acting as an antennae
 
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