Car Audio Experts needed: Added amp in my car and now get the alternator buzz.

[Skiguy411]

I recently added a somewhat cheap 4 channel amp to help drive my speakers in my car. However, now there is a buzz when the car is on that changes pitch when the gas pedal is pressed. How do I get ride of it?

Things have I tried:
Tried a entirely different head unit (I had not tried to use this head unit with an amp before).
Purchased and added a power filter from crutchfield.com (tried putting this on both the ignition line and 12 volt line)
Routed a power and ground connection outside of the car directly to the battery.
Routed line level cables directly to the amp (not near any other metal)

The only time I was able to get clear sound is when I:
Routed the power and ground cable to a battery in a totally different car
Connected my MP3 player to the amp and not the head unit
when the car is off


What can I try now? I have no idea what could possibly be causing this .

 

[Cattlegod]

go to radio shack and buy a ground loop isolator. put that inline with your RCA cables to your amp and it should resolve the problem.

link

 

[imported_nerve]

Ground the RCA's

Ground the HU to the batt

Reground the amp

 

[spidey07]

Ground.

Get a good ground for everything involved.

 

[Skiguy411]

Originally posted by: nerve
Ground the RCA's

Ground the HU to the batt

Reground the amp

when you say ground the RCAs, what is the best way to do that?

 

[Pepsi90919]

nobody mentioned this, but ground everything

 

[MrPickins]

Originally posted by: Pepsi90919
nobody mentioned this, but ground everything

do what now?

 

[imported_nerve]

what head unit is this?

 

[Skiguy411]

I have grounded everything including cutting the ground wire from the headunit and connecting it directly to the battery ground.

The radio shack thing seems interesting...although more expensive than what I would like since I have to get two of them.

 

[Skiguy411]

Originally posted by: nerve
what head unit is this?

I currently have JVC KD-HDR1, but I also tried my old Pioneer HU.

 

[imported_nerve]

disconnect 1 rca at a time and see if it goes away.

do you only get the whine from the amp'd speakers?

does the whine get louder w/ more rpms?

and then ckoutText

 

[Skiguy411]

Originally posted by: nerve
disconnect 1 rca at a time and see if it goes away.

do you only get the whine from the amp'd speakers?

does the whine get louder w/ more rpms?

The whine is basically the same loudness from all 4 speakers (perhaps slightly stronger in the rear speakers). So when I disconnected one at a time it was still there.

The problem started when I added the amp, so unamped speakers work fine.

It doesn't get really louder, just a higher pitch with more rpms.

 

[imported_nerve]

added link for rca grounding

 

[b0mbrman]

Originally posted by: spidey07
Ground.

Get a good ground for everything involved.

Yup. Sand the body if you have to.

And check to make sure every wire is insulated.

 

[Skiguy411]

Originally posted by: nerve
added link for rca grounding

Very interesting link! Thanks! Ill try that tomorrow.

 

[cKGunslinger]

Rock salt?

 

[Skiguy411]

Originally posted by: cKGunslinger
Rock salt?

huh?