alternator whine

[zerocover]

In not sure what I need to fix it.

IF the radio is turned off I dont get it.
However when the radio is turned on I will get the same whine regardless of volume. Its only rpm based with it only really comming on at 5k. I usualy turn up the music and drown it out. But sometimes I keep the volume low near 0 or mute it, and drive around thats when it bothers me/

[D323]

not a clue.

whine as in squeal from the belt, or whine as electrical directly from the alt itself?

Maybe the alt is going bad... you could get it load tested to be sure.

[goldstar]

Without knowing anything further, there are some general causes of alternator whine:

Corroded battery terminals or bad terminal connections.

One or more defective diodes in the alternator. This can cause excess ripple in the DC output that can produce whine in the audio.

Improper grounding technique causing a ground loop. Ideally, a ground point should be at zero potential. This is why single point grounds are recommended. If there are two or more ground points, particularly for high current devices such as audio components, there may be a potential difference between or among the different grounding points. In that case a ground current will flow possibly causing, among other things, alternator whine.

Unshielded or improperly shielded signal cable running alongside the power cable. This situation can induce noise in your audio circuits, heard as whine in the audio.

This is not an exhaustive list but merely things that come immediately to mind. Good luck in finding the problem.

Happy Motoring

[blue LEDz]

goldstar hit all the likely causes. the HU itself may also be defective, but before you replace that, check everything else first.

is the whine coming from speakers running off the HU, or are you running amps?

[zerocover]

I am running amps.
Im not sure however if the wine is comming from the HU or the amps. Ill do some rewireing to check.

[blue LEDz]

start by going to radio shack and buying some RCA splitters. then cut the input off, so you have 2 plugs left. on each individual plug, connect the wires together to ground out the plug. then plug them into your amp inputs and start your engine and rev it up. swap them from amp to amp to see if a specific amp is making the noise, or if the noise is gone. make sure your HU is on, in case you are using the remote turn on from that to power on your amps. if you hear no noise with the mute plug connected to your amps, then it's a problem with the HU. at that point, the next step would be to reground your HU, preferrably to the same spot as your amp grounds.

[jnorion]

You can get pretty cheap ground loop isolators from most audio shops... I had to use one in my Protege cause I just couldn't fix it any other way. It worked pretty well, the whine was only noticeable if I turned the volume completely off, revved the engine, and listened hard.

[zerocover]

Update everything seems to have gotten alot worse. I now have loud anoying alternaor whine as well as what I think is the spark noise. THe spark noise is only really audible at mute though.

I did the whole grounding out thing to find the amp was quiet when I grounded it out. Im running a 4 channel bridged to the front speakers with the rear speakers running off the HU and the sub amped. The sub has never given me any problems and the rears are fine. Could my RCA's be bad?

I bought the scorche ES034 ground loop isolator and it does nothing! Maybe its broken IDK, on the box it said it should help reduce all the above, its pretty useless though.

[jnorion]

The ground loop isolator has to be in a specific location in the system, right before the noisy component, to do anything. When I put mine in I had to try a bunch of different spots before I got it to work right. Even then it's not perfect. I think you would need to put it between the RCA's from the head unit and the amp inputs, but I'm not absolutely certain.

Most likely the amp is grounded at a bad spot or at least at a different spot than the other components of the system, and so it's picking up the whine. Is it possible to run the ground wire from the head unit back to where the amp is grounded, and then ground both amps at the same spot as well? This should take care of it, because then the grounding potential is exactly the same on everything.

[blue LEDz]

when you say the amp was quiet when you did the grounding out thing, are you talking about the mute plugs i recomended? if that's the case, then the problem is in the HU or RCA's. it could just be where the RCA's are run through the car. an easy and relatively cheap way to check that would be to buy a cheap set of RCA's from radio shack or walmart. run them over the carpet and away from other wiring. plug them into the HU and amp. if the same noise is still there, then the grounding of the HU is bad or the RCA outputs are bad. if the noise goes away, then it could be that your RCA's are bad, or they are run too close to something causing interference.

[jnorion]

If you have another set of RCA outputs on the head unit you might try using just one and then the other. I have two sets and one of mine (the one that has wires coming out the back) is bad and buzzes no matter what you do, but the other set (plugs recessed in the back plate of the deck) works fine.

[zerocover]

OK it seems like the rear amp is causing the problem, with the buzzing in the front.
Its almost totally quite if I just disconect the sub amp. So I put the gound loop isolator on the rear amp, and its alot better now.

Is this the fault of the amp, us acoustics usp-200. I checked over the ground (its on the bolt for the rear seat) and it looks fine.

Thanks guys!

[blue LEDz]

is everything grounded to the same spot? if not, it's the difference between the grounds that is causing the noise.