I hear a noise high frequency noise from speakers at 3000 rpm.
I have pioneer mp3 player and power amplifier with possitive cable connected direct to battery and the ground to the chassis.
I know that the easy way is to install a power supply filter but I think that maybe I have a missing ground or something wrong so I would like to solve the problem from the begining.
Any ideas to solve the problem?

 

Does the noise vary with engine RPM? Check the plug wires. They are supposed to supress RF but can cause interference when damaged.

Did the noise start when you installed the stereo or after the fact?

 

try moving the ground! and make sure speaker wires are not running next to power wires

 

check your battery, make sure your terminals are nice and clean, idk if its the case but when my terminal makes a shitty contace when the car is running , the speaker on my radar makes some weird *** noises...

 

Thanks for answer me.
I have new magnecor 10mm wires and new clean contacts on battery.
The cable of speaker is away from power cable.
Also I use rca to rca good quality from my stereo to rear hatch.
And yes the frequency of noise is change when rpm is change.

 

When grounding, make sure you sand off all the paint that is on the chassis, it should be to bare metal. Or try different grounds, i had that problem and it was a grounding issue.

 

You might have your amp turned up to high.

 

You didn't tell us when the noise started.

Did it start when you put on the plug wires? When you installed the stereo? After your car was struck by lightning?

Knowing when the problem started would be helpful.

 

I have do many jobs at the same day.
I have install amp,stereo,rca the same day so I can not be sure what is wrong.
But first of all I try to change the ground like pure_rx7 said from amp or clean well the chassis.

 

Make sure your ground cable is as short as possible too.......

example: If your amp is in the trunk, then ground to the closest metal part of the chassis near the trunk area.