Thanks to everyone here for their help, (especially Hugo, who started me down the right track), I think I've got it licked. Even at max volume, there is no alternator whine and no appreciable digital noise in the system (Woo-hoo!)

My solution: The Empeg wasn't properly grounded. Hugo's response got me thinking and I found a much more solid direct-to-the-chassis ground point for the Empeg. That eliminated alternator whine.

The digital noise required a filter, but I've tested with sweeps, sine-waves, and square-waves, and there is no appreciable drop off anywhere in the audiable range, at least on my system. I used the PAC SNI-1 ground-loop isolator and filter. I think the digital noise was caused by the Becker's poor isolation of the aux inputs.

Cheers, and good luck!!

ClownBurner,

Could you please comment on exactly what wire or other part of the Empeg you grounded and to where in the car you grounded it.

Thanks,

Lynn

Sure! I grounded the harness "Earth" wire directly to the chassis ground stud located at the front of the center console. On my car, it was a painted 10mm hex nut on the passenger side about 7 inches in front of the airbag computer. Mine is a 2001 so it might be slightly different than other years, I dunno. I made sure the sled was isolated from chassis ground, but I don't know if that contributed - regrounding the empeg seemed to clear up the problem immediately.

I don't know where the Becker is grounded as I couldn't remove it, but I assume they used the factory ground wire.

Hope that helps. Install porn coming soon!

Glad you are happy with your results. I have seen good noise isolation with a ground loop isolator as well, I just have to convince myself that the response is not being degraded. Perhaps your PAC isolator is doing a better job than my Radio Shack isolator (likely the case)!

Sounds like you found the same ground point that I did, just on the passenger side instead of the driver's side.

Thanks for all the help and advice.

Lynn

My solution: The Empeg wasn't properly grounded. Hugo's response got me thinking and I found a much more solid direct-to-the-chassis ground point for the Empeg. That eliminated alternator whine.

That looks suspiciously (exactly) like what I told ellweber to do way back in the beginning of the thread. But everyone always comes back with: I know it's grounded properly, etc... 99.9% of the time it's the most simple problem. If I had a nickel for every time.....

Bruno

Begging your pardon Bruno, but that is exactly the way and place I have had the Empeg grounded, since well before your post. Show us a solution that eliminates the noise without requiring a ground loop isolator in a 986 or 996 series Porsche and you will have isolated the underlying problem.

Lynn

Here's a wild thought: Have you tried merely disconnecting the shields from the becker's aux input? Often, you can do this simply by plugging the RCA cables in part-way, so that their tips touch but their shields do not. What does this do?

Send me a 986 (in a crate, on the back of a train or ship) and I'll work on it for you. Better send an extra one that I can keep and resell (not a car I would keep for myself, ugh.)

BTW, this thread is about a Boxter, isn't it? Did you grind/sand absolutely ALL the paint from the spot where you're grounding? So the ground terminals are touching a nice patch of bare metal? I'm not second-guessing you here. This is something that's obvious to me, and may very well be to you, but isn't to everyone. No bolt will provide an optimal ground despite what some people assume.

Anyway, there is obviously some difference in your setup and Clownburner's. The only thing it is safe to assume is that the empeg, barring any type of defect in your specific unit, is a known-stable platform. In some vehicles no matter how you ground the sources you're going to get noise for other reasons.

As Hugo pointed out, bad alternator connection as an example. Poor quality interconnects. Most sex/sex straight connectors are generally poor and shouldn't be used to extend interconnect. Damaged interconnects. Interconnects running parallel with other wires in the vehicle (note that the entire chasis is carrying voltage as well and you can't get around running wire near the chasis

This is the longest running problem in car audio. And still quite possibly the most elusive. But it always (always) pays to start with the basics. And the basics are enough to get the majority of people out of trouble.

Oh. And it's amazing how many installers (people working at install shops) don't know even the basics.

Bruno

For what it's worth, try the Crutchfield flow-chart. It's really good at isolating the problem, and then you can just play with the grounds on that until you hit paydirt.

Worked for me. They also sell the PAC SNI-1 for $15. Good luck!

That's what worked on the '91 Explorer I helped install in... removing the RCA shield ground.

There's still some engine noise but i'm fairly certain it's just that the factory ground sucks. We'll find out next week... thanks to this thread i've got some good ideas on how to fix it. Thanks for the updates guys.

In reply to:

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>Better send an extra one that I can keep and resell (not a car I would keep for myself, ugh.)

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You've obviously never driven one...

I think the clinical description for Bruno's affliction would be "Boxster Envy."

Lynn

One Minute in my friend's RX-7 (3rd Gen) is enough for anyone to forget about the Boxter. It will even give most any 911 a run for its money.

Anyway, I feel like the Boxter is a little style deficient. Again, under-powered for the price too. Though I can't afford a 911 right now, it's always been my favourite "classic" sport coupe. I still don't "envy" them. They're common enough that I see a few of them a week. And there are a few people at work with Boxters. My neighbor has a 911, another neighbor has some Ferrari spider and someone else around here (though I'm not sure where the house is) has a Maranello. I don't have time for envy. If I want something, I usually just go out and get it. No, I'm not about to try and sell all my assets for a Maranello.

The most stylish car that can reliably be used as a daily driver in that class however, has been my favourite since it was released in 1991: The Honda/Acura NSX. Very overpriced right now, but still a very reliable low maintenance car. My friend bought one a few years ago. Very nice. I've been trying to convince him to get an empeg (even went so far as to offer him the extra unit I bought last month).

Oh well. I'm content with knowing I can install a noise-free system.

Bruno

I envy any car with a head gasket that isn't made of soft cheese.

Rob

But soft cheese (stinky too) is great. I suppose not as a head gasket though.

Bruno

I envy any car with a head gasket that isn't made of soft cheese.

Is that what turned out to be the problem with your car? I would have bet on a fuel pump or catalytic converter failure....

tanstaafl.

No, it was definitely the soft cheese between 5 & 6 cylinders which was the problem. I plan to replace it myself, using an HKS metal gasket - just hoping the head isn't warped.

Rob

I think the issue which the ground loop isolator addresses is the poor CMRR (or non-floating input ground) of the Becker aux input.

I've seen boxster installs with no whine issues (and no isolators) where it's just empeg & amp.

Hugo

Yea, I would have done that but Speed-sensitive volume is way too cool for a convertable to give up...

Hey couldn't we just do this in all situations where we have a ground loop running through the audio patch cables? Easier than going out and buying a ground loop isolater!! My Mk1 (which had floating outputs - effectively the same??) didn't give me any noise problems, but my Mk2 has been terrible.

Hey couldn't we just do this in all situations where we have a ground loop running through the audio patch cables?

No, it does not work in all cases. Ground loops are tricky.

Well, a few minutes ago I just fixed the links and they worked after I fixed them. (Watch, they'll be broken again by the time you read this.)

Yep.

Yep.

Nope. Just checked them. They still work for me.


http://www.installdr.com/TechDocs/999501.pdf
http://www.installdr.com/TechDocs/999502.pdf
http://www.audiocontrol.com/techpapers/tech1002.pdf
http://www.crutchfield.com/infolib/S-LQI6DZj1JYu/carindex.asp?id=nonoise
http://tools.autoaudio.com/flowchart/

I just checked all five of those links and they worked.

Ack. My bad...

Dammit. I'm having a ground loop and/or EMI problem exactly as described in this thread. I've lived with it a year - it's not noticeable at soft volumes, but now I've decided to get rid of it.

The issue is that I have my empeg playing through a Blitzsafe adapter into the stock HU. I can't see how a ground loop can be happening because all the grounds are short and connected to each other. Ok, so the main ground wire is still the factory stock harness, but I *only* get this noise with my empeg. Tape or radio through the HU is fine. Having the CD selected on my HU without the empeg in the sled is also fine. It is only when the empeg is there that the noise occurs. I've even taken a 12Ga wire and run it from the sled to the battery negative terminal without any effect.

At this point I'm pretty much resigned to pulling my entire dash apart - but I still have no concrete evidence of what the problem really is. The only thought that I have is that maybe the Ratshack M-M RCA adapters between the sled and the Blitzsafe adapter do not carry the shield through. This is the only conjecture that I have that I could see causing the symptoms - that would allow the shields on the HU input side to float and pick up weak EMI.
Assuming that the HU has floating differential inputs (I think this is a reasonable assumption - it's the same HU used in VW's Monsoon option) then without the empeg in the sled both the signal and shield will float and pick up the same EMI noise, hence the noise will be cancelled by the differential input. With the empeg in the sled then the signal is driven but the shield remains floating.

What a pain.

Have you tried manually grounding the RCA shields? Or the chassis of any of the components?

Ugh. Fiddling around in the dark. And not the kind that is most enjoyable either.

Hmm. Turns out I potentially have 2 problems. Firstly, noise appears to come from my GPS box. ie, It disappears when I unplug it from the serial cable. For the record, this is powered from the remote amp line, and serial ground. The case is metal and (was) grounded to the serial ground. Removing the case ground didn't change anything. The noise from this appears to a variable length burst approximately 1/second. I'm guessing that this is related somehow to the 1/s message output from the receiver, so what I am actually hearing is the serial transmission.
So what could be causing this to appear on my empegs audio outputs? It doesn't appear to be related to the second problem, correcting the second problem doesn't affect this, and that is worrying.

My only thoughts on that subject is that my GPS transmits RS232 at 5V/0V levels and not 12V/-12V. It doesn't affect functionality - GPS works fine. But maybe the empegs serial port doesn't like 5V signalling. Even so, it still shouldn't appear on the outputs.


Second problem; EMI being picked up on the outputs. Grounding the barrels of the RCA adapter reduces it. Any barrel, F/R, L/R, helps. I'm guessing that if I gave all 4 a good grounding this noise would be eliminated.

Now I'm wondering if perhaps my 4V line outs are somehow shot. I seem to remember someone else recently having a ground issue with their sled outputs. Anyone remember where that thread was?

Firstly, noise appears to come from my GPS box. ie, It disappears when I unplug it from the serial cable.

Okay, try powering it from the 12v permanent feed and/or the 12v ignition feed instead of powering it from the amp remote line. Second, try grounding it with a proper ground instead of the serial wire's ground.

In other words, your current setup has it getting both its power and its ground from the empeg. Doing the above will change it so that it gets its power and ground from the car instead of the empeg.

EMI being picked up on the outputs. Grounding the barrels of the RCA adapter reduces it. Any barrel, F/R, L/R, helps. I'm guessing that if I gave all 4 a good grounding this noise would be eliminated.

Grounding one is probably going to be the same as grounding them all, I'd guess.

Okay, try powering it from the 12v permanent feed and/or the 12v ignition feed instead of powering it from the amp remote line. Second, try grounding it with a proper ground instead of the serial wire's ground.

Can't come from permanent. It's a stealth box with no Off switch. I suppose it could come from ignition switched, but I'd then have to fuse it. I suspect that it is a problem within the GPS itself that needs addressing - the tuner doesn't have such problems, and current consumption should be comparable. I'd really like to keep it on RA if possible. I suppose that at a push I could rebuild the interface circuit to use RA to switch a permanent wire.

Investigation this afternoon has suggested that I'm going to need to run power and ground lines to eliminate this completely.

Can't come from permanent. It's a stealth box with no Off switch.

So's mine. I've left my car sitting for days at a time (long weekends and such) and the GPS hasn't yet drained my battery.

I suppose it could come from ignition switched, but I'd then have to fuse it.

Don't understand. Your ignition switched power should already be fused. Just connect at a point after the fuse.

Have you tried grounding the gps to the common ground instead of using the serial ground? Does the gps even have seperate serial and power grounds?

Matthew