[byrds8]

I had new 6x9s installed along with a 4ch amp for the cabin and a mono sub amp for the sub. There was also a PAC LP7-4 LoC installed as well. Now there is a buzzing sound when the lights are on for any reason. This is to include the DRL. If I turn the lights off the sound goes away. Also, if the car is not running and the lights are on there is no buzz. The pitch and volume of the sound does not change with the RPM of the engine itself either. Anyone have any ideas how to get rid of this noise? Its not coming from the amp because I have unplugged the RCA inputs and the noise goes away. Thanks in advance.

 

[patriotpa]

Simple. You've got a ground loop.
Noise isolator on the RCA leads to the amp. https://www1.crutchfield.com/p_127SNI1/PAC-SNI-1.html?tp=61807

 

[byrds8]

I thought the ground loop was for alternator noise? I get no noise if the lights are off at all. Minimum if the lights are hand turned on and a lot more if they are on auto.

 

[byrds8]

It seems the buzzing is only slight when the headlights are on vs the DRL. Does anyone know if the headlights and the radio are on the same circuit?

 

[patriotpa]

Different fuse.