Electrical/audio Noise

I am installing a new Rio Car/ Empeg in my Porsche Boxster. I hear a lot more audible noise than I think that I should be hearing.

I am running the Empeg front audio outputs into the factory Becker CDR-220 head unit aux inputs. Ground is to the Becker harness ground wire, very close to the head unit end. +12 vdc comes from the console harness.

I am hearing alternator whine as well as a lot of noise from the Empeg internals, both with and without the disk spinning.

Adding a ground loop isolator to the audio lines eliminates the Empeg noise but not hte alternator whine. At the same time the low frequency response is somewhat degraded so I would prefer to avoid the isolator if possible.

I would sure appreciate any advice any of you might offer. I see little reference to this type of problem on the install notes part of the board.

Lynn

There's some tips on reducing alternator whine both listed and linked here. Good luck!

For starters don't use the factory ground for either the empeg nor the other head unit. Find a place on the floor of the car under where you have the heads mounted. Hopefully somewhere where there's already a bolt of some sort. Remove that bolt and sand/grind any paint/finish off the metal surface. Put some loop terminals onto the ends of your ground wires and make sure they touch that bare metal - put the bolt back to hold it tight.

Next is trying a different interconnect between your empeg and stock unit. Try a shorter length and different type of interconnect. I just used CAT5-e UTP for mine (1 pair of wires for left and 1 pair for right - the other two pairs unused - everything mended nicely with heat-shrink tubing).

Bruno

I also have a Porsche Boxster (2001 S) and have the same problems...

The Empeg isn't the source of the noise; I can disconnect it from the head unit and the AUX input on that unit will display the same problems. The FM doesn't seem to suffer it though.

While I concur that a good grounding is an excellent idea, and I just might try using some CAT5 for interconnects, I think the AUX input of the Becker factory radio just blows goats.

If you make any progress in solving these problems, please do let me know, and I'll do likewise.

Thanks for the inputs

Tonight's experiment was to run a piece of #12 stranded (soldered to the terminations) from the PEM nut on the back of the Empeg sled to the Faston tab on the Becker shell. This provided the best result yet for Empeg noise, but I can still hear it.

I am convinced that the Empeg digital circuitry ground currents are present in the audio output shields as evidenced by the fact that it will operate without any other ground.

I agree with you about the Becker, the Aux in has a small pigtail shared for both channels, on a wimpy little connector pin.

Redoing the grounds so that the Empeg power is not routed through the Becker's wiring harness might help but I have, so far, tried to avoid tearing up the Porsche's harnesses. I already have virtually no interconnect, just a pair of double male RCAs between the two harnesses. Do you have any problem with alternator noise?

Lynn (2000 S)

I do have alternator whine, but with the gains on my amp all the way down, I don't usually hear it. It kicks in with volume set to 25-30 and I usually listen between 14-20, but it's there, no doubt. I'd love to eliminate it completely. The stereo shop says that some alternator whine is normal with the Becker head unit but I'm not sure I believe them.

I was thinking of installing one of these, but it might well cost me 5x more to install than to buy, considering how hard it is to get to the Boxster's engine.

Have you tried just extending that #12 wire to one of the ground bolts at the bottom of the center console, to see if referencing them both to chassis ground would help? The factory ground may be weak.

I am convinced that the Empeg digital circuitry ground currents are present in the audio output shields as evidenced by the fact that it will operate without any other ground.

I'm not sure what you're trying to say here. Are you saying "I can lift the ground on the empeg and it still runs, so I know they've got their audio stage wired poorly"?

If that's what you're saying, I think you're drawing the wrong conclusion from the evidence. What this tells me is not that there's anything wrong with the empeg, it tells me that you've got a serious ground loop problem that you need to solve. Have you run through any of the diagnostic steps in those PDFs that I linked in the FAQ?

The installdr.com PDF's return 404's.... I think the link structures have changed, as one of the seems to be
http://www.installdr.com/InstallDoctor/TechDocs/999501.pdf here now...

The installdr.com PDF's return 404's.... I think the link structures have changed

[censored] [censored] [censored] [censored] [censored]. I hate it when that happens. Web rot sucks.

I checked them when I made that first link, too. He must have changed the installdr site within the last couple of days.

Working on it...

What really pisses me off is that I'm tempted to just grab those PDFs and permanently host them at Riocar, to avoid just this sort of problem. But I know that would probably not be allowed by the author.

Is the site even up anymore? I had to use Google's cached copy of one of the PDF's last time I had to look something up there..

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.)

All I am saying is that no matter how well I ground the Empeg to the car, there is still some current from the disk and the digital circuitry flowing in the audio ground that makes noise in my head unit and that I can correlate to the disk activity, display changes and/or button pushes on the Empeg.

I do not know what the circuitry actually looks like but it is certainly not behaving like it is optically isolated. In fact, so far it is not any quieter than the Neo-35 that it replaced.

Further, I am concerned that if I tear up the Porsche harness to the Becker head unit (which is totally quiet by itself, playing CDs or the radio through an ADS P640) and go to a star ground configuration then I will still have a noise path through the audio cable shields.

I am not throwing stones at either piece of equipment, just trying to get rid of the noise with minimum modification to the car harnesses.

Lynn

All I am saying is that no matter how well I ground the Empeg to the car, there is still some current from the disk and the digital circuitry flowing in the audio ground that makes noise in my head unit and that I can correlate to the disk activity, display changes and/or button pushes on the Empeg.

Right. That's a standard, every-day, run-of-the-mill ground loop. It's not the empeg's fault. It's just as isolated as any other aftermarket head unit, and if you tried to add a Sony minidisc player, you'd get the exact same thing. When there's a DC ground loop, there's very little that you can do within the head unit to stop it. It has to be fixed externally by tracing the fault.

Every time you add another component to a car audio system, you increase the chance for ground loops. Start by going through the various steps in those troubleshooting documents. Check your wiring, Lift grounds on various components and connections, etc. Go through everything systematically one at a time.

If you can't mess with the becker system, you may have to add/lift grounds to it or use an isolator. This is all part of the standard procedure for solving this sort of problem.

(You are using a Mark2 empeg, right? Not a Mark 1?)

I'll try and get through the Crutchfield flow chart tonight or tomorrow and post my results.. Maybe I can at least isolate it.

I have a Mark IIa and I am going to try moving the Becker ground out of the harness tonight.

I would point out that the factory CD changer (made by Sony for Becker for Porsche) mounts in the front trunk and is connected only to the head unit and to no other grounds anywhere in the car. This system has motors, processors and serial data all living together with no noise, that I am aware of, reported over the last 5 model years.

It seems possible to make a system that truly does isolate the audio.

I will report on results of rewiring later. Thanks for all of your input. I have identified at least four Boxster S/Empeg installs here so perhaps we can find a viable solution jointly!

Lynn

I am very anxious to hear your results. I didn't make it to the flow chart tonight but I should be able to tomorrow, and I'll post the results as soon as I have them...

ClownBurner,

Sorry for the delay but I do now have some results to share.

I have reduced the noise to where it is tolerable for me but probably woiuld not yet be considered "audiophile" quality. I have cut the Becker ground (large brown wire on pin 8 of the black connector on th eback of the Becker) and returned it to one of the 6 mm studs under the console. I have the Porsche wiring diagrams (2000 model year) and this is welded to the body and considered a primary ground reference. You can find it by pulling off the driver's side carpeted panel on the console and looking just behind (toward the rear of the car) the airbag sensor assmbly.

The Empeg ground is returned to the same point. I still have the #12 wire between the two units as removing it causes a substantial increase in noise level.

The alternator noise is bad, in the Empeg only. I was able to reduce it by adding a generic line filter to the +12 input to the Empeg. It is now at about the same level as the Empeg noise sources.

I would estimate the signal to tnoise ratio to be about 40-45 db. This estimate is obtained by reducing the Empeg volume until the music and noise sound about the same amplitude. I usually run the Empeg set to -9 db as this balances the level with the Becker radio and CD sources. I run the Becker at about 20 typically and the noise is really inaudible when the engin is running and the car is moving. With the doors closed, windows up and car and engine stopped, I can hear the noise still at a very low level when I pause the Empeg. I realize I can gain some S/N improvement by turning up the Empeg but it is nice to have all sources at the same level.

I have tried both a DC-DC inverter (supplying the Empeg +12 line) and a Radio Shack Ground Loop Isolator in the Empeg output lines. Both eliminate the Empeg noise from the Becker and both have other disadvantages.

I am eager to hear the results of your experiments.

On another subject, I saw in another of your posts that you had made a display filter to move the Empeg amber closer to the Becker/Porsche amber. I do not have access to AutoCAD or CorelDraw so I am wondering if you have the template in any more generic format that you could forward?

Thanks,

Lynn

Here's the template file with the correct colors in EPS format, I have no idea how it'll come out but it's the best I can do. I guess I could try .PDF but that might not preserve the colors very well.

One of these colors should come pretty close to the Porsche display when printer on your printer and combined with the amber screen.

I'll try moving the grounds tonight and a few other experiments I have planned, and see if that makes a difference. I'll let you know what I find.

PS: How do you get the back of the Becker unit without removing it from the dash, or do you have the Becker key and you're pulling it out?

And if you're S/N is 40-45db, you're a lot worse off than I am, mine's more like 70db and even that drives me nuts. I assume you've already dialed in the gain to your amp all the way down?

Whoops, here's the file

Thanks for the EPS file. I guess I'll need to cut out windows for the IR devices.

I do have the Becker keys but I think you can get to it by removing the AC control panel. Just pry off the surrounding bezel gently and then remove the upper two screws to extract the AC panel. If your hands are not to large you should be able to get the connectors off the back of the Becker.

Further study of the Porsche wiring diagram suggests that the big brown wire goes to a ground point very close to where I moved it, but I haven't been able to find the other end yet!

It sounds like the S/N is more than 40 db but I don't have a good way to measure it. I think that the current state is quite tolerable but I will await your results.

Lynn

Forget the empeg-specifics for now. You have a noise problem period at this point. I suggest you go to www.carsound.com and search around to see if anyone has posted concrete Boxter information. You'll have to wade through the noise on that forum unfortunately.

If you can get an aftermarket harness adapter for the Boxter factory connection you can more easily run tests that bypass the Becker unit completely. Then you can try running power directly to the battery, etc. to see if it has any effect.

I'd probably get rid of that Becker unit anyway, simply because it looks far too ghetto to installed in a decent looking car.

Bruno

The empeg audio outputs are not opto-isolated, no. I don't know of any head units that do have opto-isolated outputs. Take your average sony/kenwood/etc and you will find the audio outs are grounded to the chassis.

Generally, the aux *inputs* of a head unit have floating ground with high CMRR input stages - this subtracts the ground reference from the signal and gives you clean audio, no matter if there is noise between the receiving unit's power ground and the sending unit's audio ground (which sounds like your problem).

Have you tried any audio ground loop isolators (not ideal,obviously) between the empeg and the becker?

There was a boxster with an empeg install (+eq+amps, no becker) which cambscar did - it had awful noise on it. They bought it round here and I couldn't find out why. In the end it turned out to be the alternator had a bad connection - it was completely silent after this was fixed!

We do have a pretty low noise floor - lots of people have commented on it. It does look like the becker's aux in stage may not be ideal, though. The becker/changer setup is a designed-in system and most likely *does* have high CMRR inputs.

Hugo

Well I can't get to the Becker, so running a ground between the two chassis will have to wait for now. I was able to determine that the ground loop ONLY happens when the Empeg is connected to the AUX in of the Becker unit. Even when set to AUX input, there is no noise if the Empeg isn't connected. There are two kinds of noise present:

1. Empeg electrical click-pop-whirr noise that is linked to drive activity, and
2. Alternator whine

Both seem to be related to a ground loop. I disconnected the ground on the Empeg and grounded it to the chassis directly and still had the same problems, so I suspect I will need to have my stereo shop disconnect the Becker factory ground and ground it to the chassis directly, then install a bridge wire between the two chessis, as you have done.

I installed a PAC SNI-1 ground-loop isolator between the Empeg output and the Becker input and it reduced the click-pop-whirr noises to inaudiability, without any noticable effect on the low- or high-end frequency response. I recommend it. It did not, however, have any affect on the alternator whine.

Anyone have any suggestions on what to try next??

Are you 100% sure that the empeg ground is connected? If you're grounding through the audio grounds, and this is the only ground, the tracks aren't really big enough to take it and it will cause audio issues.

You should, as with home use, not be able to hear any drive noises on the audio. I can plug the empeg in at home, pause it, turn the amp (80w rms) to max and not hear drive noises with my near next to the speaker cone.

Can you check the alternator?

Hugo

I find this to be true at home as well but at home you have a power supply that is floating so there is no ground current from the digital part of the Empeg circuits possible on the audio shields. I have found that a floating dc supply in the car also eliminates all the noise.

I think we are fighting the fact that the Boxster's Becker head unit AUX inputs are not isolated from the chassis ground adequately.

ClownBurner,

You can get the Becker keys by calling Becker at (888) 423-3537. The part number is BNA-1184.989. They cost less than $2 when I bought mine, about 18 months ago.

I am about to go back to the DC-DC inverter if I can find a place to put it. This really does solve the problem but I do not want to run it all the time and I don't like to pull the power on the Empeg so abruptly. Perhaps Hugo can comment on the downside of doing that in the car environment.

I have also considered using a diode gate to provide power when the car is off but this would require setting the inverter to an output voltage that is higher than the highest voltage ever seen from the alternator and counting on the audio cables for a ground return. Again, perhaps Hugo can comment on what circuitry is between the digital ground and the analog ground inside the Empeg.

Lynn

Hugo,

Yea, if I disconnect that ground (coming off the loom) the Empeg won't power on at all, so it's gotta be grounded. I have it bolted to the chassis.

Interestingly, my ohmmeter says that there is a ~7ohm path from the Becker aux-in to the chassis. From the empeg outputs to the chassis is 1 ohm. I get continuity tones from both.

Where exactly is the DC-to-DC inverter connected? Between the 12V power and the Empeg, or the Becker?

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:

---

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

---

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

Oh I'm sure that Ignition switched is fused somewhere. But I wouldn't have a clue at what rating.

I'm going to redo the basic install The Right Way(tm). I've just bought a Monster 10Ga amp kit to handle permanent power and ground for the HU and empeg. I'll have to hack my sled harness around somewhat to cater for it.... Hmm. I need some 10Ga capable quick connects.

After that I'll look at the GPS again. It was a quick and dirty hack in the first place. I know that there's room for improvement there.

try powering it from the 12v permanent feed and/or the 12v ignition feed instead of powering it from the amp remote line

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.

You could have it come for permanent through a relay activated by the amp remote line. Maybe.

Yeah, that's probably where I'm headed.

And after pulling my entire dash apart again this afternoon, and buying all the little odds'n'sods needed to redo the whole thing, I notice that the audio ground connection of the Blitzsafe is tentative, to say the least. How I didn't notice this before is beyond me. (Although it's hardly over-engineered). I'm now wondering if all the alternator whine will disappear if I simply correct this, and if I could have saved $30 on parts. Oh well, in for a penny...

Well, fixing the Blitzsafe didn't fix the problem, although it needed to be fixed. I'm sure that having an audio ground hanging by a thread is not a good thing. It was a PITA to get the socket out of the housing in order to resolder it. And then when I was done soldering the socket, I discovered that was not enough slack on the audio signal wires for me to be able to place the ground socket back in the housing, so I had to unsolder it, place the socket halfway in the housing, heatsink it somehow to prevent melting the socket and re-solder it. Way too much fun for my liking.

Anyway, as I said, that didn't fix it. I eventually traced it to being a bad ground connection at the sled connector. I couldn't see anything wrong with the crimp, but for some reason wiggling the wire made a difference. I also discovered that both microphone crimps were bad, and the amp remote line was virtually out of the connector. (I'm sure that didn't help with the GPS noise!)

So I ran a 10ga ground line to the back of the sled using the 4mm threaded hole, and then tapped the existing looms ground into it. That seems to have fixed the alternator whine and empeg noise completely. What (very little) noise remains doesn't appear to be empeg-related - I can also hear it if I play a blank tape. I'm guessing that it's just noise picked up on the 12V line in the loom. When I ran the ground line, I included a beefy 2 position molex connector, so I could easily add a 12V line too. I'm now trying to decide whether to take it from the distribution block behind the driver-side dash, or go the hassle of running it through the firewall straight to the battery. Hmm. Decisions.

Cool, glad you got it fixed.

Where'd you run the 10g ground to?

At the moment is run to an unpainted dash support strut that's bolted into the tranny tunnel. (Yeah, ok, it's a FWD car, but the shift linkage still has a tunnel...). Looking around under the dash, the dash supports are used as ground for other stuff, and I think that's as good as I'm going to get without either running out to the battery or drilling myself a new hole in the floorpan. I'm lucky because the strut has had material removed to lighten it so I've just been able to run a 5/16 bolt straight through it and tighten a nut on the other side.

Yeah, that's the correct place to ground it. The only time you'd want to go to the trouble of running it to your battery is if you'd had trouble with that grounding point.

Is grounding the harness AND the sled a common thing to do?

Ideally, the harness ground and the player casing should be the at the same potential anyway. At least I think that's how it's built, many other car stereos are made that way.