Car Stereos: whine,crackle,pop, ground loop noise, pheonix gold

Question
QUESTION: Brian, I've been troubleshooting this for a week now.. its intermittent and seems to happen only when car is running and stereo up loud, i've grounded the rcas at deck, using shielded rcas, relocated deck ground, tried noise isolator, quadruple checkd connections, rereouted rcas opposite of power/ground, levels are precise.. please help

alpine deck, two 15" diamond audio d9 subs, brutus 2000d amp, diamond d6 components, pheonix gold amp for comp.


ANSWER: Hi Jason,

As you're finding, intermittent noise problems can be extremely difficult to troubleshoot.  However, from what you're describing, it really doesn't sound like any sort of induced noise or ground loop noise.  If that was the case, you should be noticing it most with the volume at low levels, not high levels.  

At this point, I'd have to suspect a defective component.  Are you hearing the noise just through the component speakers, or is it coming through the subs as well?  If you get it through the speakers and the subs, then your problem may be in the head unit.  If it's just the components, then the Pheonix Gold amplifier may be at fault.  (I'd also listen to see if it's just coming through one of the speakers, rather than both; use the balance and fader to see if the noise goes away when you turn a speaker down).  I recently had to replace an Alpine PDX4.100 amplifier because of an intermittent noise in one channel.

I think your best option at this point is to try to isolate the problem as much as possible, then try substituting components to see if it solves the problem.  (I understand this may be difficult or impossible to do if you don't have the resources of a shop available).  

Hope this helps!

Brian

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

QUESTION: Well, high volume and bass seem to cause it, but it is most noticeable at low levels, even with the volume at zero you can hear a whine, also there seems to be a static field throughout the car.

Answer
Jason,

The only other thing I can think of to check would be the battery and charging system.  If you have corrosion or loose connections at the battery terminals, a battery with a bad cell, or a malfunctioning alternator, it can cause excessive AC ripple which will result in noise in the audio signal.

Good luck!

Brian