My 88 IROC has a Kenwood MP-145 head unit that feeds two 5 1/2 inch speakers in the dash as well as a Kicker 650 w amp (through a capacitor). The amp feeds two 6 x9s and two subs. I am noticing that only when the radio is turned OFF I get a whine in the two 6x9s. The whining noise begins 15 seconds or so after I shut the radio off. There is no whine when the radio is on (even when the volume is turned all the way down). Any suggestions?

 

do you have rca running along side the power/grnd wires?
that will sometimes cause feedback on speakers, try running them down other side of car or separate them from power/grnd wires

 

The RCAs and power lines run down opposite sides of the vehicle already.

 

Is your amp wired properly to turn on/off with your deck or does it stay on when the radio is off? My guess is that the amp is staying on and you're hearing some induced noise. Where/how is your amp grounded?

 

I had a similar problem, try a rca ground loop isolator between the amp and the head unit. I got one from Radio Shack, redirecting your wires away from the power source is a good start but sometimes does not eliminate it totally. here is a link

http://www.radioshack.com/product/in...ductId=2062214

 

Easy fix!!!! Buy some brandname RCA patch cords. Most RCA's have the copper wire that run straight within the rubber coating. This style will introduce magnetic noises that are emitted by power sources such as electrical motors or current from and energized cable/wire. So to eleminate this potential noise, get "shielded cables" or twisted cables. Having a proper grounding source will also help. Use a "star washer" for the grounding point. If the noise still doesnt disapear even with the proper cables, you'll need a ground loop isolator. If that still doesnt work, make sure to run the RCA's away from any motors. If that doesnt work, then find a different grounding point.