strange noise

Hi all,

Ive been installing a system into an 03 Silverado. It includes Clarion DXZ 825 HU, PG EQ-X, (2)PG MS-275's, and a sub.  I decided to try running the 2ohm OEM Bose speakers off the amp. All that has worked so far. I may put in my MB Quarts to replace them....but they'll do for now. But the real problem is the sound that comes through the speakers when the system is powered up, and changes as the vehicle (diesel) is started.  Its not a hum like Ive heard from other systems, it sounds more like an open mic, (but not feedback) . When the vehicle is started there is obvious  alternator buzz.  I have tried changing ground every which way, changed cables, both of the two batteries, and even a different Clarion HU. Always the same sound. The HU speaker output does not produce the sound. And a completely outside source does not produce the sound. So its not the signal line, nor the amps/speakers. But when a HU is connected its there.  I am using a GMRC 2.3 to give me the switched + and a headlight / door alarm. I eliminated it as well as the culprit.  I hope this mostly makes sense. Any ideas would be appreciated.

thanks

deezle

yes, ive tried all new cables. no change.

Thanks though

        Have you tried grounding the shield of your Rca jacks.   There is a good chance that you have a burnt trace inside your radio.   Just ground one end of a small wire then touch the other end to the outer part of your Rca connector.    You can do this at the amp or at the radio,  if it makes a loud pop and starts working right that is your problem.   There is a simple fix for this. Just let me know if you need assistance.

For sake of argument, i tried your theory (not the solution),  but being that I tried two different HU's with same results made me think that wouldnt be it.

Thanks

Thanks for reply DYohn, I tried grounding the HU from several different points.

I got maybe a 1 db cut in the noise when commonly grounded to the amp.

This has been puzzling me for days. Ive got an electrical engineer thinkin

about it now too....here's to hopin'....i appreciate all your guys advice.

Its been a great site for just killin time and reading through the forums.

thanks