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Posted: 4/1/2006 1:39:34 PM EDT
Changed out my POS Rampage amp (pos, but no alternator noise), with a "higher quality" Jensen amp. I was just using the Rampage to power my sub, but "upgraded" to the Jensen, which will now run my 3 ways and a sub at the same time.

Everything is hooked up correctly, but I now get a little alternator noise. Why?

Thanks.

vmax84
Link Posted: 4/1/2006 1:43:21 PM EDT
Try re-grounding all of your components to the same point. If that fails, unhook one part at a time and you might be able to figure out what component it is.
Link Posted: 4/1/2006 1:47:00 PM EDT

Originally Posted By H-barCarbine:
Try re-grounding all of your components to the same point. If that fails, unhook one part at a time and you might be able to figure out what component it is.



Forgot to mention that I am using a couple extra patch cords, of probably lousy quality. I'll have to check that as well with the grounds.

Thanks.

vmax84
Link Posted: 4/1/2006 1:48:19 PM EDT
With higher current devices, you're best bet is to run heavy gauge cables directly to the battery.

I've had high current amateur radio amplifiers suffer from alternator whine when connected only to the fuse panel, but the whine disappeared when I went direct to the battery with 8 AWG wires.
Link Posted: 4/1/2006 1:51:48 PM EDT
You have a grounding problem. To make a long story short, you need a "common" grounding point for both your CD player and the amp.

Here is how to fix it. First take out your deck and find the ground wire. If it is in a wire harness with a bunch of other wires snip it off and strip it. 90% of the time it will be a black wire. Then attach some new wire to the piece you just stripped. Use good crimp connectors or solder it and tape it. Run that new wire to the heavier ground wire of the amp, yes, even if it is in the trunk. Put a good ringed crimp connector on these. Next scuff the paint off a peice of metal from the chassis of the car next to the amp so you can see the metal underneath the paint. Drill a hole or use a self tapping scew and screw the connector right to the chassis. Problem solved.....

It doesn't mean that the amp is defective, it is just unpredictable why a certain combination of components will do this while another will not.

Another solution would be to get an in-line preamp filter, but that is more of curing the symptom rather than removing the cause.
Link Posted: 4/1/2006 1:55:45 PM EDT
Ground loop



Grounding problem,like others have stated,ground at same location.
Link Posted: 4/1/2006 3:03:51 PM EDT
[Last Edit: 4/1/2006 3:05:50 PM EDT by INI]
Also make sure that your power and line level audio cables are not running together, I usually do power down one side and the signal cables down the other side of the car.

If the signal cable is pinched or shorted to ground because it got nicked by a screw, it also makes an instant groud loop, causing noise.
Link Posted: 4/1/2006 4:35:20 PM EDT
Thanks for the help. Give me something to do tomorrow.

vmax84
Link Posted: 4/1/2006 7:40:38 PM EDT

Originally Posted By SWS:
With higher current devices, you're best bet is to run heavy gauge cables directly to the battery.



This is true.

By its nature, an alternator produces pulsating DC voltage ("ripple"), which is smoothed out by the battery. The lowest amount of ripple is present at the battery posts - the further away from the battery you connect the stereo components, the greater the amount of alternator ripple that remains.

Make all DC power connections directly to the battery posts. (Note that if you do this for both the positive and negative sides, you'll also automatically eliminate most ground loop problems.)
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