SoCal: Desperate for help with alternator whine!

**vettejock99** · 02-18-2006, 01:35 PM

Hey folks,

I went to the Audio Toyz shop here in Mission Viejo today to seek professional help with my alternator whine. I was thinking that it would be a fairly simple fix for a real pro. After all, virtually everything (except the monitor and a USB hub) is in the trunk of my car. No head unit, the wiring to the trunk (as part of the amp install) was done by Circuit City. I even bought an ADD51T to try to simplify things. So, the only real components to deal with here are the inverter, the power strip, the PC, the USB sound card and possibly the DSP.

Anyway, the guy started by saying the problem is my power strip, and that he'd also upgrade the wiring everywhere (even though it is 4AWG to the amp and ground and basically 10AWG everywhere else except the actual speaker wire) - again, stuff that Circuit City did and seems perfectly fine from what I've read. So, give 'em 6-7 hours and they'd "fix" it.

I really would prefer not to do this, because (a) that's like $400-500 and I am already WAY over budget on this and more importantly (b) I REALLY want to know how I am still getting this whine - I want to understand how to fix this. I am not the dumbest person on the planet, and I simply cannot figure out how I haven't broken the ground loop via the optical link.

I live in South Orange County (Ladera Ranch, near Mission Viejo). Is anyone willing to let me drive over (or swing by here) to take a look and maybe help me fix this? I'd be happy to throw a bit of cash, beer, steak, whatever towards somebody who can help me fix this and understand it. Please let me know....

Mark

**DRWeside** · 02-18-2006, 01:57 PM

When you say 'power strip', what do you mean? Is that a DC distribution block or an AC powerstrip?

Are all of your components grounded to the same point?

What kind of amplifier do you have? Is the PC case grounded properly?

The specs for the add51t don't say anything about an optical output; Only optical input. I'll assume that you're connecting this to the amp via regular RCA cables.

Still too many questions though. I would take out the PC and see if you still have noise with just the ADD51T and amplifier turned on. Work backwards from there.

**Matthew230** · 02-18-2006, 02:19 PM

What we need to give any advice would be a diagram showing how things are hooked up.

By optical link I assume you mean the link from the sound card to the amp ?

If so, switch off the PC, get something else like a DVD player with an optical output, plug it in at the mains not the inverter and try that, if you still get a whine then you can assume that the whine is coming from the amp. If you don't then it is occuring within the soundcard or before the signal gets to the soundcard.

Other things you can do, are to connect headphones to the PC see if you get the whine, try plugging the PC into the mains etc. You need to know at what section it is occuring before you can even think about solving it.

Obvious, but have you tried a ground loop isolator, many people have alot of success with these.

**vettejock99** · 02-18-2006, 05:04 PM

Sorry guys, I should've mentioned it, but a lot of people have seen my last 3-4 threads where all of these questions (except the power strip one) have been answered.

The short answers are yes, optical input to the ADD51T and RCAs to an Audiobahn amplifier (whine existed with another amplifier, doesn't exist when it is just the DSP and amp).

It is an actual power strip, 3 prong, into the inverter (and yes the noise exists when the PC is hooked to building power, so it isn't the inverter). I don't have noise when I plug an MP3 player into the amp.

So, it does in fact seem to be something with the PC or the way something is wired. I am working on a diagram right now - should have it done today. I just feel like someone can look at it and go "disconnect that right there" and we'll be in bid-ness.

I'll post the diagram as soon as I finish it.

**DRWeside** · 02-18-2006, 06:45 PM

3 prong power strip into an inverter that only has leads for +12V and ground? Does the inverter have internal circuitry connecting the neutral prong to ground?

Try running a grounded lead to that neutral prong. It doesn't matter if you use the same ground lead that the inverter's ground is connected to.

**vettejock99** · 02-18-2006, 10:26 PM

Originally Posted by DRWeside

3 prong power strip into an inverter that only has leads for +12V and ground? Does the inverter have internal circuitry connecting the neutral prong to ground?

Try running a grounded lead to that neutral prong. It doesn't matter if you use the same ground lead that the inverter's ground is connected to.

I'll have the diagram done before I go to bed late tonight, but in answer to your question....I guess not, now that you mention it. By a grounded lead - how do you mean? Think I could take some 10-12AWG wire from the common ground and loop it around the neutral prong? If that is the case and it helps, think that will be in, or will I have to do that to the neutral prong on the PC plug which is plugged into the power strip as well?

**DRWeside** · 02-18-2006, 10:34 PM

Common ground and loop or solder to the neutral prong? Yes.

Will you have to do it to the neutral prong on the PC plug as well? If the powerstrip was manufactured to spec, you shouldn't have to.

**vettejock99** · 02-19-2006, 01:27 AM

Originally Posted by DRWeside

Common ground and loop or solder to the neutral prong? Yes.

Will you have to do it to the neutral prong on the PC plug as well? If the powerstrip was manufactured to spec, you shouldn't have to.

Thanks, I'll look at that Sunday. BTW, here is the diagram (if I can figure out how to post it). Sorry if it sucks...

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**vettejock99** · 02-19-2006, 01:36 AM

Oh yeah, the reason the 3 cables show red is that that is obviously the place where it is different when I try to use the optical out from the Audigy to the optical in on the ADD51T with RCAs to the amp. In that case, I draw the power for the ADD51T from the 12V rail of the PS on the PC. Like I said, I get the whine either way, so the diagram shows my preferred hookup.