OK..I have had it with the ground loop ignition whine on my Miata install! The installer had put a noise supressor between the HU and my amp, but the supressor has two brown wires coming out of it that are not connected to anything!!!! Looking at Crutchfield it seems that they are ground wires. My question is: Do I ground them to the main grounding point for the system in the trunk of the car? Do I combine the two wires then run one jumper wire to the ground? Is the reason why the whine did not go away in the first place due to the fact that these ground leads were never in fact grounded?

Also, the installer used one grounding point in the floor of the trunk. The ground for the amp and the HU are joined in one crimped connector then are attached with a screw and star washer. However, the connector is a small spade connector and could it be that it is not making that much contact with the chasis that I am not getting a good enough ground connection to reduce my whine?

Thanks for all who read this and care to advise!!

Ed

Greetings!

I have similar alternator noise problems (typically only with significant load, AC or electric heat / defrost), but I have the same noise filters you are talking about. I tried grounding them, but heard absolutely no difference in the sound. I think you are on the right track with the grounding, but I do not have enough experience to advise you on this.

Let me know how this works.. I'm looking at getting one of those supressors after Paul brought it up in another thread.

wht type of problems r u having with ur car?

Alternator whine and I've tried everything in the world... I never want to show off my empeg because of it...

Greetings!

If it is any help, I use them in my own car. They help mask the problem. They do not fix the root cause (I have not tried to find that yet...), but they do help. And, I know what you mean - I am a little ashamed of the sound of my install too because of it.

Did you try one of these? I ordered it from Crutchfield with some other stuff. At the time, I had whine. Before it arrived, my installer was able to take care of the whine without using filters.

I kept it simply because I am too lazy to send it back. If either you or Paul want to borrow it, let me know.

Greetings!

I actually have one of them sitting in my desk. I have been too lazy to install it... When I get ambitious, I will try to track the source of the whine. Thanks for the offer, though!!!

That particular PAC alternator-attachment product worries me a bit. At one point when trying to diagnose a ground loop, I tried it, and it did not solve the problem. But more importantly, its connection method is rather "iffy" at best. You have to essentially disconnect your alternator from the car and run it through that thing instead. The problem is that its wires are much thinner (by an order of magnitude) than the alternator wires it's replacing. I did not leave it hooked up for very long, I totally didn't trust it.

Besides, it can only kill noise coming directly from the alternator itself. If you've got a ground loop in the car, you're getting noise from a lot of other places in the electrical system, not just the alternator.

I actually swapped out my HU with a friends of mine HU, and lo and behold...no noise! e-mailed Rio on the issue and was told to send my HU in for servicing, all expenses paid by them, as to them it sounded like an output problem within the unit itslf. Hopefully they will be able to find something and I will be much happier!!!

Will keep u posted on the outcome

Ground loops are caused by multiple return paths with different voltage potentials between them. Alternator whine is a function of the electronics ability to isolate from noise on the supply rail. That being said, I have a basic rule I follow when doing car installs (and I have done more than I care to remember). Bring +12v and ground from the battery posts using a suitable gauge wire to support your total system load (amps, x-overs, headunit, etc.) to the area you will be mounting your amplifiers (by far the highest consumers of current). Then, using distribution blocks, run power and ground leads from there for all equipment. No exceptions. If you're really worried, then isolate the accesory input to your headunit with a small relay, so your headunit is only supplied from the block (not typically nescessary). This way your car battery acts as a big alternator noise suppressor (it's low impedance) and ground loops... well, what ground loops ?
Works every time

I'll vouch for that. I had some nasty whine and took the path munkworks suggests, including a relay on for my switched power line and 95% of the noise is gone. The remaining 5% I can only hear when I'm parked without my vent fan on and I rev up the engine to 3000 rpm or so.

-Zeke