Car Stereos: crackling speakers, even when the HU is off..., crackling speakers, factory amps

Question
QUESTION: Hey Ed.  I own a 2005 Scion xA with all factory pioneer speakers and head unit, and the dealer installed bazooka tube.

I've never had any audio problems until last saturday, problem is the speakers crackling, like rice crispies.
They crackle when the car is running, only durring idle.  As soon as I pass about 1500 RPM the crackle stops.  It even keeps crackling when I turn the head unit off completely.

The crackling is not affected by using the power windows or power locks, but it does buzz a lot worse when I use the power windows.

Any ideas?
Thanks

ANSWER: Hi Matt.

its the noise only on the door speakers or its present on the subwoofer too?

That noise could be due to a bad ground and or signal interference

i would have the factory amps checked maybe a ground lead came loose somehow.

if its on the subwoofer that'll be easier to determine whats the problem.

cheers.

Ed.

---------- FOLLOW-UP ----------

QUESTION: Hey Ed.
Its only the door speakers and tweeters making the sound.
I unplugged the sub and the sound still continues, so I'm pretty sure that's not the problem.  Earlier I meant to say that the power mirrors make the buzz louder.

How can I check for bad ground leads or signal interfearence?

Thanks!

Answer
Ok Matt.

you would need to locate your factory amps.to be honest with you i have never worked with a scion before so i don't know their location i would do some research. or i would call the dealership see if they have a wiring diagram, or look for one online. that way you can see where are the factory amps grounded at.

there is another question to be asked did this noise started after you installed the additional amp and the sub?. the only reason i ask its because on my experience you get engine noise (signal interference) when you run the power wire and RCA wires together.

i hope this helps man. sorry if it didnt.

but if that was my car and i wasnt able to figure out wats wrong i would just get me a little 4 channel amp and bypass the factory amps.

by the way letme know what was wrong if you get it to work
cheers.

Ed.