okay i just finished hooking up my amp (4 channel, sony headunit) and whenever the car is off no hissin noise comes out. whenever it is on with the engine it is making a hissing noise. please help as soon as possible since i still have everything apart. thanks!

 

Does the noise change pitch as you change the engine RPM? If so..... sounds like alternator whine. If not...... could be a few different things.

 

it only made noise when the car is on. when i put in in reverse to move it stayed about the same whine. does the fuse have to be screwed onto the frame for the amp kit? i have it just there. thanks. what other problems could cause it? i bought some rockford fosgate kit from best buy and the rca's have like a small ground wire coming from the middle. do you know anything about that? thanks again

 

Make sure everything is cleanly connected to the head unit and amp so that there are no loose wire ends anywhere. I got a scratching/hissing sound when one wire was loose and was tapping against my doors when i went over bumps. Double check that ur using a clean ground or factory ground too.

 

i think ill check that out. the wires are kinda just thrown back there since it is getting really late. some of the wires off the wiring harness were not used so i should just cap them off or something. thanks wheelmanz28. any other suggestions?

 

My friend's Jetta use to do this. Check the grounds.

...he would tell people it was a turbo

 

I would think if it was something like that, it would happen even with the engine off. He said it's only with the engine on. So I would think it's engine noise of some kind. My guess is alternator noise. Also, I would try to avoid factory grounds if at all possible. Is you head unit connected to the factory ground wire? If so, I recommend running it to the chassis. The factory ground is used for many other pieces of equipment.... most not even audio related!!

 

i the hu ground running to the factory ground of the harness. where else is there a ground around there? the amp is grounded to the screw of the passenger side seat since the amp is right under it. i had to remove the seat to screw it down and the screw seemed like a logical place. is that my problem? thanks a lot again. is there a way to get rid of the alternator whine? or am i stuck with it?

 

Since you have the amp so close to the head unit i would just take a wire and run it from your amp's ground to the head unit ground and disconnect the factory ground on the head.

 

Do your RCA cables use what is called "twisted pair" construction? If not they should. RCA cables claiming to use "double" and "triple" shielding are useless in a car stereo setup if they don't use twisted pair construction. This design rejects radiated noise from the car that shielding alone can't.

 

the cables are those rockford fosgate gamma ray rca's. they are like 60 dollar rcas for a pair. luckily i get a discount. they have like this small little ground cable coming out from them but i do not know whether to ground it or not. cause it is only a small piece. im gonna try grounding the hu some where else too. see what happens. thanks a lot

 

The wire that you are talking about on the RCAs is for the remote turn on for the amp.

 

If you remove the console, you can sand the paint off the trans hump and drill a hole for a ground for the head unit. You might also run an extra ground from the radio chassis to this point as well. Might help.

 

Is the gain on the amp set correctly? If the gain (input sensitivity) is too high it will pick up noise much easier. Make sure it's set correctly and not just cranked.

 

The little wire with your RCAs is a remote turn-on lead. The small 16 or 18g wire (often blue in color) that turns on your amps when you turn on the CD player. And twisted pair design is a must when selecting RCAs, but I don't think that would be the cause of noise in your case. You say it's only with the engine on..........................you know what?.................. I think it might be engine noise of some kind.
You don't have to drill any holes to find a good grounding point. Find a bolt that's already through the chassis. Unscrew it. Scrap away ALL the paint and dirt. We are looking for shiny metal here. Clamp your ground wire under the bolt and you should be good to go. I recommend moving your head unit's ground to chassis. Never use a factory ground wire.