Noise With A Difference

[aphid]

hey guys,

in my quest thisarvo to finally knock the average plug / alternator noise i've been getting through my amp, i think i've made the situation alot worse. as it was the noise was quite loud, enough for me to leave the amp for the rear speakers & sub unplugged.. now the sound is about three times as loud and i'm also getting a humming of a much higher frequency when the motor is off, and the only thing's on are the amp and headunit. I was fidling with the amp positioning and wiring (rear 6.5" run through the amp) when I heard a bit of a pop through the sub which was when the noise got louder, and upon turning off the engine the normal buzzing alternator / plug sound disapeared and was replaced with the much higher freqency sound, definently running alot higher than any of the equipment in the car which leads me to believe that it is the headunit itself.. i swapped out amps to make sure that the RCA earth wasn't shorted out at the amp, and have isolated the sound coming from both RCA plugs (ran an ipod directly to both channels on the amp with the engine running and no noise), so i earthed both ends of both of the RCA cables , which had a negligible effect on the sound. I used the existing wire that runs with both of the RCA cables to earth it, and did not actually splice into the braid on the signal wires themselves.. I'm thinking this wire is there to stop and induced currents that the RCA plugs might pick up along there path to the boot, and probably cured my original prolem, anyway this leads me to believe that i must've somehow shorted the RCA earth at the headunit which is giving me these wicked noises through the amp.. has anybody else got any oppinions or advice on my situation?

cheers and thanks in advance guys,

mark.

[danielr34]

Try running other RCA's just on the outside over seats to see if it is the RCA's themselves, if the problem is still there, there is a good chance that the pre-amp in the deck is not healthy, try another deck even an older one that works if you can get your hands on one.

[aphid]

yeah. i believe i've done something to the pre-amp, is there anything else i can do to help short of opening it up and attampting to fix any burnt tracks..? i've heard of running filters but with the range of frequencies i'm getting i feel i would also be filtering out alot of frequencies associated with the music i would like to be listening too