killcarputer startup noise 05 d'max bose

I've installed a carputer in my 2005 Duramax with OnStar and Bose using a GMOS-04 to retain door chimes / OnStar functionality. Not totatlly sure I like the module. The computer is powered by a Carnetix P1900 PSU that starts the computer when it senses +12v on it's specific turn on wire - which is supplied by the GMOS-04. Things work pretty well except for the fact that the Bose amp is apparently on all the time (I'm sure for the chimes), which picks up all kinds of noise from the computer/psu untill the computer actually turns on (5-10 seconds) and fires up the audio. Some of it's from the PSU's fan, and some of it sounds like noise from the computer itself, plus there's popping noises when the thing first gets power ((computers being kinda noisy). I'm wondering if there is a way I can either filter the noise, or put the Bose amp on some kind of startup delay. The PSU does supply a 12v amp turn-on wire that's on a delay. Anyone have a solution, I'm thinking I lose my door chime until the PSU tells the amp to turn on..

Lets consider that you actually have 2 problems (unless i'm misunderstanding)

1) you have noise in your 12v system (suspect the PC and PSU) and you can hear it in your speakers

2) you want to delay the start up of the PC

#1) You will use low value ceramic and electrolytic capacitors, and or unductors (ferrite core) to regulate the noise on the 12v supply going to your amp and HU AND the 12v - 12v conveter for your PC.

(make sure the body of the PC is well grounded)

#2) buy a time delay relay, DIE makes one as do other companies, search the forums for previous posts about this subject.

All this is a $30 usd fix and about an hour of your time. You need the correct diameter shrink tubing and some solder\iron, several matching spade lug connectors that fit the spades on the relay and a wire stripper.

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I know just enough to be dangerous. VERY dangerous.

Thanks for replying 1) correct 2) I want to delay the start up of the Bose amp OR kill the noise There is no HU... just the GMOS-04 (unless you're counting that as the HU) I have a timed 12v output from the carnetix PSU... I think all I really need to do is find out how to either shut off the bose amp (and lose my door chime until the carPC starts), or just kill the noise so it's reasonably silent until the carPC starts (less than 30 seconds) I will search, but are there circuit diagrams you could point me to for the DIY power filters you are describing? Thanks

There should be tons of filter circuits you can buy that are already designed to eliminate alternator noise etc

While I dig through some stuff, you can search for the term "How to eliminate noise in audio" and you will read posts with the same conversation we are having.

Probably someone else here that works day-in-day-out in car audio will be able to recommend a product etc.

THE KEY WORD here is grounding. Ground everything. ground that PSU and MB, ground the case, ground the amp . . .

If it's not plastic, ground it.

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I know just enough to be dangerous. VERY dangerous.