Car Stereos: stereo noise, rca cables, rca outputs

Question
Brian:

First off, thanks for your expertise. In my 2004 gmc sierra I installed a new system. The system includes two amps.  One Orion 500w actual power is 643 W for the bostons in the front and rear.  The second amp is  for the punch 3 with dual 4ohm coils- 12 inch sub.  It is a punch amp with 1000W.  I drive everyday and use maybe 20% of the systems potential, but every once in a while I like to show off. While I'm driving around I get a lot of noise, almost like I have a supercharger.  Would upgrading the alternator reduce noise or do I need to get a noise reducer? What do you reccommend?

Answer
Hi Hunter,

Sorry about the delay in answering this question.  I don't think upgrading your alternator will help the noise problem, unless it's being caused by a defect in your existing alternator (possible, but unlikely).  Noise filters (ie, ground loop isolators) may or may not help, depending on the cause of the noise problem.

I'm not sure from your description, but I assume that you're hearing "alternator whine": a high-pitched sound that changes tone with RPM, and disappears when the engine isn't running.  This kind of noise can be very difficult to track down, and there are many potential causes.  The first thing I'd do is try to isolate the source of the noise:  Is it coming from all your speakers?  Just the front and rear?  Just one pair?

You might try disconnecting the RCA cables going to the subwoofer amp, and see if that makes a difference in the noise from the front and rear speakers. This is especially true if your sub amp's RCA's are coming from the Orion amp's RCA outputs.  

Another thing to check is the condition of the connections at the battery; make sure they're clean, tight, and free of corrosion.  If your battery is in poor condition, it can lead to noise problems too--if you still have the original battery in the truck, it's probably due for a replacement.

If you continue to have noise problems, please follow up with more details on your system design, including the head unit, and the exact nature of the noise.  I'll try to help you troubleshoot the problem as best I can.

Hope this helps!

Brian