static

hi i have a friend that says when he breaks his subs will play static like sounds. now the first thing that came to mind with me is ground. but i was wondering what all of you knowledge able people could help.

Probably picking up interference from either an ABS system, or the brake lights. But the ground is a good place to start.

could be induction

the RCA's to the subs are picking up "pops" from the lights to the brakes. Try moving te RCA's.

i found the problem the rca was lose he told me he checked it but when i went and looked it was almost about to fall off.

it's cool you found the problem, it threw me off 'cause you said it only happened when the brakes was applied.
maybe it was moving around with the car movements since it was barely connected...

there wasn't a ground on the one that was loose, so everytime the brake lights when on it induced a pop

oh ok i get it

heres something: 2 weeks ago i put up my backseat because i went to a busy mall that has a theft problem and i have my amp's on the back of my seats and during the putting it up it pulled 1 rca off just enough to make that channel have really bad alternator whine so i am wondering how could that make it have alternator whine when that rca was not even close to any power/ground wires.

the signal voltage going thru rca cables are so small, (mV) its very easy to pick up
noise, as a matter of fact, it can induce thru ground easier than it can thru a
grounding cable...

yep, this was one of the reasons they went to 4-8V outputs on the headunit - it has more immunity to noise. As for the half unplugged RCA, the signal ground was gone so it was a LOT more suceptible to noise.