if i disconnect the RCA cables from the amp the interference stops.

would that indicate its not an earth problem, and is more likely to be due to the RCA and power cables being run together?

yup

As matt said yes that would be your problem. But that had nothing to do with unpluging them and it stopping. TBH 99% of the time the interference is coming from the RCA anyway.
Also are you using the standard HU sorry i forgot.
Oh and silly boy you were told that before lol, we just made emphasis on your dodgy earthing as a bit of Alternator whine would be the least of you worries.

nah, not using standard unit.. got a dvd 7inch flip out one

so moving the RCA's to the other side will more than likely get rid of the interferance.. and moving the earth, even if its not causing the interference is highly recommended?

Just move the RCA's. If that cures it then fine, it it doesnt then move the earth

Yup

punto_matt said:

Just move the RCA's. If that cures it then fine, it it doesnt then move the earth

Click to expand...

He has the earth daisy chained between amps so he needs to move them all to one point each amp earthed to the chassis.

Oh yeah i forgot thats how it was earthed lol. So erm yeah change it

been reading all that i can find about alternator whine, but it wont go away!

ive earthe the RCA barrels, all earths go to one point, earth point is properly prepared and tight in the spare wheel well, power runs seperate side to RCA...i cant think where to go next.

ive posted up on mp3car forum, all they suggest is a pre amp...but i dont see how this would resolve the problem...

Tried turning the gain down and different RCA Leads?

on third set of rca, (now using home cinema quality leads). if I turn gain down it does go but, I loose volume....I just answered my own question, with a pre-amp id need less gain to attain same volume, and id have less interferance.....know any good pre-amps?, this is the last hickup in the whole carpc thing...

You got there in the end
Gain amplifies anything that is in the signal weather it should be there or not. Let me have a look into preamps at lunch.

Just out of interest why are you not using an external sound card, is it the cost?

i am im using the creative x-fi 5.1 usb hting (which is a BITCH to get to work after hibernate resume, but i did it ), the sound is amaizing, theres just this REALY annoying noise, its exactly like coyle originally described, volume doesnt change just the pitch, and when driving with family (hence quiet or no music to cover it up) it REALY pisses me off altho parents are to old to be able to hear it

oh and im using a delta box (2nd hand off fleabay), because the 2.1 output option from the x-fi was very nice to listen to, but you couldnt get enough base out of the sub channel, so im splitting the front channel 3 ways, still sounds realy good, just more base. what do the knobs for each channel do??

and ive realised, cost is just an obsticle you have to deal with, u cant make a half arsed attempt and expect it to be brilliant...