Other sources of alternator whine....
 

ok fellas...... if my system is off and i have alternator whine..... what could cause this? it's not super loud but it is noticable when my stereo is off or at low volumes. how much should you hear? i don't remember ever hearing this when i had the stock stereo but if my system is off it has to be coming in some other way, right? any thoughts or comments would be great.
does upgrading the stock ground wires to the battery help any? right now i have 75x2 in the front and 500W rms to my sub. will soon have 100x4 rms inside plus the sub.

I asked about this a stereo shop yesterday. Their guess was it was caused by the line-out converter if you have the stock head unit still in. Upgrading the cables couldn't hurt but in my last car I as never able to get rid of it entirely.

Are your amps powered on when the stereo is off?

no converter....... i don't have the stock HU in.

the amps should'nt be on because i have a remote turn on lead from the HU but i'll check.

Try to isolate your wiring as best you can.

Speakers can pick up noise regardless of whether your HU/amps are on or not - just from electrical interference.

An example (kind of): A guy who lived near me had an illegal CB radio booster in his truck. Anytime he'd use it near my place, I'd hear the other end of his conversation through my computer speakers and stereo - even if the systems were 100% OFF! And his booster would also make my computer start going haywire - if I was working on something, all of a sudden the Start menu would open, windows would close, and eventually, I'd have a lockup.

I know you're not dealing with CB radio, but check all the wiring. Definitely could be a bad ground, or another power wire "leaking" interference into your system (remember, you don't need POWER for interference).

Could be so simple as having the powerr cable for your amps crossing the stock battery cable, or an alternator cable, at just the right angle or position. Shake things up a bit, check your wiring, and shift any close-contact wires around some.

~HH

See if any of the amps are on when the radio isn't. Visualy verify this don't assume.
How are the amps connected, RCA's or speaker level?
Are they run on the opposite side of the car?
WHere is the grounds for the amp?
Are they together?
Did you clear the paint before grounding?
Is the battery in the front of the car or did you relocate it to the back?

Pull the speaker wires out of the amp and see if it still happens. I had the same problem some time ago but I honestly can't remember what caused it. I think it was a combo of a shorted RCA with a relocated battery.
CHeck with a multimeter to make sure the RCAs are OK. If the ground is dissconnected internally then things like this can happen. Also pull the RCA's off the amp and see if the noise goes away. I have seen amps draw power through the RCAs or ground through them while malfunctioning and it cuases them to stay on also somethime the rempote wire has a loose strand by the amp and is touching the power terminal or wire.

Is there any way to get rid of the alternator whine with the system on? It gets kinda annoying after a while. However, I don't get a whine with it turned off.

I had problems with alternator noise recently, but I got it solved. I had this ticking/sparking noise that can only be heard when the system is on (with engine running) and the gains on the amp set to moderate levels. The weird thing was that it can only be heard on the passenger side but not the driver side.

Anyway, some things you want to check/do:

1. Check ALL ground to all your HUs and amps. This is the most common cause of noise. As 1st MP3 said you should clear the paint (use a file or sandpaper) where you secure your ground wire. Might even want to tap a new ground for your HU and forget about the ground in the factory wire harness. Keep all ground wires as short as possible.

2. Isolate the cause of noise. The most simple is to disconnect the RCA that goes into your amp and test it with another source (like a portable CD player) or use a muting plug, while having the engine running. If you hear noise, then the problem is with the amp wiring (power/ground, speaker wires etc). If you don't, then it's caused by the HU or the RCAs. Doing this will eliminate half of uncertainties/guesswork.

3. Check the RCAs. See whether they are are crossing any power or speaker cables. Also, I highly recommend getting some Unshielded Twisted Pair RCAs. This was what actually solved my noise problems (yeah, i couldn't believe it also) :D