Tweeter buzzing when lights are on

[N20]

I fitted a new head unit on Tuesday an In-phase IPX1

everything has been fine with it until i turned my lights on tonight.

When i turn my lights on i get a buzzing sound which only comes out of the tweeter on the passenger side and it gets quieter when i dim the dash lights but does not stop.
If you turn the volume up the buzzing does not get louder and as soon as you turn the lights off it goes away

anyone know what is causing this???

[N20]

just adding no sound comes out the tweeter when it is buzzing,
but as soon as you turn the lights off the buzzing goes and the sound returns

[N20]

I have spent all morning trying to find the problem

if you take the key out of the car and turn the lights on all the dash lights up and so does the headunit but you cant turn it on because the key is not in.
the head unit lights up when you turn it on anyway.

This is the only thing which i can think could be causing the buzzing sound,
is there a way to stop the head unit lighting up when i turn the lights on??
This is probably a question for Mike

[lespurgeon]

My guess was you are picking up a ground (sorry earth on here) humm - I would pull the tweeter and make shure nothing is contacting metal body that shouldn't be.

[N20]

Thanks that is what i thought it was, i have pulled out the head unit and made sure everything is OK and nothing is touching and its all fine.
I will pull the tweeter out tomorrow and have a look its just strange it only happens when the lights are on

[N20]

I have still been unable to stop the buzzing which only comes out the passenger door tweeter when the lights are on.

i have been thinking of getting a GROUND LOOP ISOLATOR and putting it from my head unit to my amp, but i have no idea if this will fix it as i only run a sub off my amp no speakers.
the speakers run off the head unit.

do people think that a GROUND LOOP ISOLATOR may fix it even if no speakers run off the amp???