earthing problem

[TegCrazy]

i helpd to hook up my mate system on his vti coupe but theres a horrible engine noise cumn thru the speakers. the amps are mounted to the rear seats. the weird thing is if the seat are down then theres no noise at all. whats up with that ?? as soon as u lift up the seat and they click in the noise is back

[Fhrx]

Like I said on the other forum, check your signal cables are no where near any power cables.

Secondly, check the earth is secure. Also check the cables are not being squashed by the seat when it is down.

[nedgeworth]

What size ground cable are you using and where have you got it grounded too?

[poid]

i assume the amps are screwed into the rear seats, and there is metal back there?

Could possibly be some wierd ground loop or somethign happening...when clipped in the metal in the seat is grounded, and then so is the amp and its creating engine noise?

If thats the case then simply screwing some MDF onto the back of the seats and then screwing the amp onto that may work.

Otherwise it'd have to be something like cables getting squashed, cant think of any other reasons

[Rowie]

i had a very similar experience with a head unit install I did on my old car.

What had happened was like what the other guys pointed out. I had put a screw through the side of my cable going down the passanger side door/floor panel.

Just double check any screws you have going down the side of any mouldings or seats are not getting squashed or folded up together.

Also check for kinks in the cable when you move the seats up and down

[Rowie]

and yes, would help if you tell us where you are grounding it to.....

[TegCrazy]

POID- ur a legend mate. you were rite cos the amps were screwed to the back of the seat, we were gettn that engine noise. so i screwd a piece of MDF down and now there no noise at all. by any chance could you explain how screwing the amp one the back of the seat was creating that group loop?
thanks again.

[Rowie]

Could possibly be some wierd ground loop or somethign happening...when clipped in the metal in the seat is grounded, and then so is the amp and its creating engine noise?

Theres your answer right there

[Rowie]

The metal screws screwing directly into the metal backing of your seats, created an extra ground when the seat was up. Due to the metal on clipping mechanism on the seats connecting to the "GROUND" chassis of the car.