grounding an amp

1.  Scrape all paint off the body where you are grounding.  You want bare metal of the car's chassis.  Do not use an existing bolt like a seat bolt or something as the bolts used for construction to not conduct electricity well.

2.  Be sure you are connecting the ground BEFORE you connect power.

3.  It's generally not the best idea to run a ground back to the battery.  You want your ground cable to be approximately 18" long or shorter.  The shorter the better.

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Support the12volt.com

Grrrrrr, unless the resistance on the ground return can not be made to co-operate, then ground back to the battery.

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Top Secret, I can tell you but then my wife will kill me.

ditto... i had an Acura in here last week that the cleanest i could get the system was to run a 4 gauge ground all the way from the battery which virtually eliminated the noise problem.... you really have to take it on a case by case basis... yes there are things you normally want to do first as mentioned above.....

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Kevin Gerry
Certified Electronics Technician
MECP First Class Installer

Owner/Installer
Classic Car Audio
since 1979

i grinded to bare metal and it still makes that wistling sound.

You need to determine how the noise is entering your system. Is your amp ground the proper gauge for it's current rating? Use the same gauge for ground as you did for power. Disconnect your amp's inputs and see if there is still noise. If there is you have either a ground or power problem or your amp is defective. Some brand of amps are known for producing lots of noise due to their design and choice of internal components. You could also have noise being induced into your speaker wires. Try using a short set of wires to any speaker and hook it up next to your amp to eliminate any problem from speaker wire routing. If the amp doesn't make noise you then need to short out the inputs to give the amp a zero volt input. If there is noise then retry the first few tips to troubleshoot. If there is still no noise, then short out the amp's input RCA cables at the radio. This will test if the routing of the RCA cables is to blame. You can also try running a test set of RCA's outside the vehicle to see if the RCA's or their routing is to blame. If there is still no noise you need to continue up the audio signal chain using the same methods. Adding anything into the audio signal chain raises the risk of adding noise.
Don't forget to check your battery's connections. Make sure they are clean and tight and that the ground from the battery to the body is good and clean.

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sparky

what kind of rca's are you running and do you have them ran on the same side of the car as you do your power wire.  btw, what kind of car is it?

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paint and body       
"semi-professional"

before you try anything. run a extra 4awg wire from your batt ground to your chassis. grind a spot clean, drill a hole and use a nice new clean machine screw to bolt it on. then try your other amp ground.

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Big Dave