Payment made for the answer

**jjh221** · 11-03-2004, 07:07 PM

What kinda vehicle? Where is your computer located at? Im still confused on how you have the audio hooked up? is it out from pc to HU and you also have a cd changer? Where have you tried grounding? Have you tried grounding your mobo, not the case, to another ground that is factory in your car like cig lighter?

**davem** · 11-03-2004, 07:14 PM

Ok, I guess that's right, since we already know it's a ground-loop problem we must isolate where it's coming from exactly.

Here's another idea that might isolate whether it's a car wiring problem or the computer itself causing a grounding problem... Since you have an OPUS you can fairly easily hook it up temporarily to someone else's car (aligator clips to the battery would suffice). Then see if the noise is still there. If it is then you know you have to ground out your computer better!

Or you could just try another computer in your car, but that's a bit harder to do.

**antimatter** · 11-03-2004, 08:10 PM

I think that there are to many variables that come into play while running the wires to the actual location for that test to work

**dragonBTV** · 11-03-2004, 09:30 PM

first things first

connect your opus150 to battery derictly by a pair of twisted lamp wire

and tell me the result (start engine/stop engine)

NO GROUND AT ALL NOW!

**antimatter** · 11-03-2004, 11:02 PM

If that works let us know.

The concensus is to keep ground as short as possible.

I think that there is something else going on here. I think that he has two sets of noise.

I think that he may have some problems with the opus power wires (the ones that plug into the drives and such) running near the motherboard circuitry.

The other alternator whine is becasue of a bad ground.

What gauge wire are you using. Use atleast 8 gauge

**MatrixPC** · 11-04-2004, 10:45 AM

Originally Posted by Matthew230

Ok, I did it by simply identifying the audio lines, cutting them at the back from the CD changer and attached female RCA plugs. A little more basic than your method.

Are you saying that you fixed the problem by grounding the audio from the CD changer line to the same point that you grounded everything else ??.

And to do this will I need to cut the ground wire from the CD changer end rather than just splicing it ?????

From computer audio ground, just connect it to the audio ground from the changer. Treat the audio ground just like another signal wire.

From PC -- To -- CD changer cable.
PC Audio Right ----> CD/HU Audio Right
PC Audio Left -----> CD/HU Audio Left
PC Audio Ground --> CD/HU Audio Ground. NOT to HU or CD case/ground although they seem to be the same, but I have engine whine if connect audio ground to the case.

**yunusyu** · 11-04-2004, 11:11 AM

I have not heard you say that you RAN THE POWER WIRES ON ONE SIDE OF THE CAR and AUDIO WIRES ON THE OTHER..Any power wire...check all the amp wires..black and red

good luck..

**Matthew230** · 11-04-2004, 05:48 PM

Originally Posted by yunusyu

I have not heard you say that you RAN THE POWER WIRES ON ONE SIDE OF THE CAR and AUDIO WIRES ON THE OTHER..Any power wire...check all the amp wires..black and red

good luck..

Thanks for the advice, though this is not my problem, since the actual audio wires run with the CD changer cable. I have also tried wiring direct to the battery over the roof of the car with no improvement.

**Matthew230** · 11-04-2004, 05:53 PM

Originally Posted by MatrixPC

From computer audio ground, just connect it to the audio ground from the changer. Treat the audio ground just like another signal wire.

From PC -- To -- CD changer cable.
PC Audio Right ----> CD/HU Audio Right
PC Audio Left -----> CD/HU Audio Left
PC Audio Ground --> CD/HU Audio Ground. NOT to HU or CD case/ground although they seem to be the same, but I have engine whine if connect audio ground to the case.

Thanks for the info. You'll have to bear with my, I am quite technically stupid, but how do I find the PC audio ground??

And when I do I link it with CD changer ground....right ?????

(I have a feeling this may be the answer, it seems to make the most sense!!)

**davem** · 11-04-2004, 09:06 PM

Whoa... I just got my new 4-channel amp and my 'carputer totally installed. Big problem, Horrible alternator noise!!! I quickly panicked because I have been keeping up with this thread and I was scared I was going to have huge problems! I went to RadioShack and got their ground loop isolator and it works great now, no signal noise whatsoever (inverter issues though

).

So all I can add is... you definately tried a good ground-loop isolator?