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?