eliminating alternator whining

I must have read all the faq's and previous posts on this subject, and this is what I found using this advice:

I checked the mass cable from the amp to the car chassis.
It turned out to be rather loosely screwed to the car, and the installer did not bother to scrape off the paint.

After scraping off some paint and using a bolt to really tighten the screw to the chassis,
I managed to reduce alternator whing with 50% (no scientific measurement, I should add).

Another test I did was to feed the Empeg with the AC adapter.
Apart from almost blowing my speakers (home volume was 100%),
I found out this totally eliminated all audible alternator whining.

So, how should I proceed:
1) look for an even better amp mass cable connection
2) get a power filter for the empeg
3) other

Thanks for any suggestion,
Pim

Well, did you read through those PDF files I linked in the FAQ? Those have a lot of details to go through. Go through those carefully, one step at a time. Some of what you're describing sounds like it could be due to ground loops, and those PDF files will help you track it down.

One thing that's often overlooked is inductive noise. The audio cables are probably picking up a lot of the noise just from being in the general vicinity of other wiring. They are acting like radio antennas and picking up the noise from the car's and amplifier's power/control wires.

I recently re-routed all of my audio cables to run through the center of the car instead of the side. It helped reduce the noise I had in the system (which was very slight to begin with). As I was doing it, I discovered that even moving the cables around behind the dash would change the amont of noise in the system. Keep this in mind as you're diagnosing the problem.

Also, check to make sure there aren't any loose wires on the docking connector, or elsewhere in the system. If your wires were crimped instead of soldered, re-check all crimps. Better yet, replace all crimps with solders.

___________
Tony Fabris

Since connecting the Empeg with the AC adapter eliminated the whine. I would assume that you are getting the noise at the empeg unit and wouldn't mess around with your amps any further.

When you have the empeg on AC power, is it out of the dash? Perhaps you only get the noise when the unit is in the dash and the wires are all compressed together. This would be inductive interference or a stretching of the wires at the docking connector.

Perhaps you don't have a good ground at the empeg unit or the power leads are coming from a bad source like close to the ignition coil. This should occur whether the unit is in the dash or not but on battery power.

I get noise when the unit is in the dash only. I haven't quite figured out how to eliminate it except for removing the unit from the dash. I can duplicate the noise by putting some of the wires close to the unit or to each other. I need to play around with it more but it hasn't bothered me quite enough.

Since connecting the Empeg with the AC adapter eliminated the whine. I would assume that you are getting the noise at the empeg unit and wouldn't mess around with your amps any further.

Not true. Ground loops can be tricky things to debug. Even with what he stated, it still could be a grounding issue with either the amps or the empeg. These things are all interconnected.

___________
Tony Fabris

Well, did you read through those PDF files I linked in the FAQ?

Yes, I did. In fact the scraping of paint and bolting the mass cable comes right out of document 999502 which did really help. According my interpretation of the PDF document, I should focus on the amp power cables to eliminate the remaining noise.

But I also used this Cruthfield diagram which, if I follow it leads me to this conclusion: Noise is being picked up by one or both your receiver's power leads. Install a noise filter on one or both of the leads.

These two different outcomes made me post the original post in this thread.

One thing that's often overlooked is inductive noise. The audio cables are probably picking up a lot of the noise just from being in the general vicinity of other wiring.

It might be worth to note that I bought the best RCA cable I could find: Diehl (red) triple-shielded with aluminium foil as the third shield.

As I was doing it, I discovered that even moving the cables around behind the dash would change the amont of noise in the system. Keep this in mind as you're diagnosing the problem.

Having followed the Crutchfield diagram, I did play the Empeg out of the dash. My RCA and power cables were long enough to put the Empeg on the passenger seat. This meant the RCA cables were totally stretched rather than stuffed inside the dash. This alone did not effect the noise problem.
Powering the Empeg with the AC adapter, while on the passenger seat did.

Also, check to make sure there aren't any loose wires on the docking connector, or elsewhere in the system.

You mean the AUX and serial connectors? Yes, they are loose. Should I seal them or cut them off?

If your wires were crimped instead of soldered, re-check all crimps. Better yet, replace all crimps with solders.

Which wires are you referring at? My speaker cables are crimped. My RCA cables are moulded. My ISO cables are from the factory. I do still use the diode cable that was necessary for my previous car, as it also holds the resistor that is needed for my carphone. Oh, and yes, the carphone is using the same power supply as the Empeg.

As the carphone and all the audio cabling was done by my car dealer's carphone specialist, there is not much I can change without breaking things. My installer did confirm to me that he routed the power cables and audio cables on separate sides of the car, though.

Maybe I'm just being too fussy, maybe there is some amount of noise which just needs to be accepted. The noise I am hearing can only be heard at low volume, or when the player is paused. If the volume is cranked up, the noise cannot be heard.

I invite anyone to come listen at Amersfoort to hear whether I am hearing a more or less than average amount of noise.

Thanks,
Pim (60 GB, red)

Well, did you read through those PDF files I linked in the FAQ?

Uhm, one of them suggests to "connect everything to a common ground".

How do you do that in a practical way, when your Empeg is in the dash and your amp is in the trunk?

Uhm, one of them suggests to "connect everything to a common ground". How do you do that in a practical way, when your Empeg is in the dash and your amp is in the trunk?

Run a heavy-gauge ground wire between the trunk and the dash, and make sure that neither the Empeg nor the amplifier are grounding through their chassis.

Of course, this defeats the "keep ground wire runs short" rule. You can try both (grounding to two points on the metal frame with short runs, or grounding to one point with long runs), and see which one works best. If there's no difference, then go on to the next diagnostic step.

___________
Tony Fabris

Noise is being picked up by one or both your receiver's power leads. Install a noise filter on one or both of the leads.

I used a 20-amp noise filter from Radio Shack, and it's installed on the main power lead that comes straight from the battery. My Empeg and amps are both powered from this lead. This did significantly reduce the noise in my system immediately after I installed it.

Also, check to make sure there aren't any loose wires on the docking connector, or elsewhere in the system.
You mean the AUX and serial connectors? Yes, they are loose. Should I seal them or cut them off?

No, I meant are there any bad/frayed/intermittent connections at any point in the system. Including the wire ends that were crimped into the docking connector at the factory.

My installer did confirm to me that he routed the power cables and audio cables on separate sides of the car, though.

Confirm this yourself, don't take their word for it. And remember- it's just as important for the audio cables to be routed away from all other car wiring, not just your amplifier's power wires.

Maybe I'm just being too fussy, maybe there is some amount of noise which just needs to be accepted. The noise I am hearing can only be heard at low volume, or when the player is paused. If the volume is cranked up, the noise cannot be heard.

If your amps have their gains properly adjusted, you should not hear any noise when the player is playing with the volume turned all the way down. Remember that you should be able to play your empeg at 0db (maximum non-overdrive volume) without damaging your ears or your speakers. If you can't turn up the Empeg that loud, then you've just got your amps set too high.

Other things to try: Methodically eliminate all components that might be causing the problem. For example, disconnecting the car phone stuff temporarily. If there's an EQ or crossover in the system, try removing that, etc. Try lifting grounds. Try adding grounds...

It might take some work to elimintate the noise, but eventually you'll be able to get there.

___________
Tony Fabris

Not if you:

1) Measure the runs to be the same length
2) Make sure they are both the same gauge
3) Coil the wires in a circle if they are too long
4) Thread them through a ferrite torus



One of the few remaining Mk1 owners... #00015

Run a heavy-gauge ground wire between the trunk and the dash, and make sure that neither the Empeg nor the amplifier are grounding through their chassis.

Would a starting cable be any good?
Or buy another amp power cable and use that for ground instead of 12V?

I can think of ways to connect a heavy-gauge cable to the trunk, but to the dash? What kind of connector would one use?

Thanks for your help,
Pim

Would a starting cable be any good?

You mean like a jumper cable? Gosh, no, that's overkill.

Or buy another amp power cable and use that for ground instead of 12V?

Right, that's the sort of thing I'm talking about. But don't do a permanent "serious" cable run at first. Just wire it up "loose" and see if the noise problem goes away. If it doesn't, then start looking elsewhere. If you can do the experiment without spending any extra cash, that's the best way to go.

Another thing to check: Make sure none of the cables the phone-installer-guy put in are grounding against the chassis anywhere. For instance, they might be bent over a sharp edge of metal and their sleeves might be making contact with the car body somewhere. Check the entire cable runs for problems like that. There should be no contact with the body of the car by any component except at the exact ground points you've decided upon.

I can think of ways to connect a heavy-gauge cable to the trunk, but to the dash? What kind of connector would one use?

No, what I mean is: Decide upon one single grounding point for all of your equipment. That grounding point is most likely a paint-scraped bolt somewhere on the car. Wire it so that the empeg and the amps ONLY ground to that one single point. Meaning the ground wire from the empeg and the ground wire from the amp both go to that single point, therefore you might need a long cable run for one or both of them. I don't want you "connecting the dash to the trunk", that would be silly.

___________
Tony Fabris

3) Coil the wires in a circle if they are too long

wouldn't it be better to coil them in a figure eight then fold it in the middle to make a single coil? I use this method when ever I'm wrapping any cable. there is a way (which is too complicated to explain here) to coil it in figure eight fashion in one coil in one hand. This way the current is flowing in opposite directions with each turn, cancelling itself out. It has the added benefit that there are no twists in the cable and it sits flat.
However, if possible, and as it's an installation, the cables should be trimmed to the correct length. More cable, more chance of induction.

4) Thread them through a ferrite torus

I'll have to try this one too!

Murray 06000047
I don't think, therefore I am not.

One thing to check: disconnect the audio cables from the sled, so that there is nothing but power connected to the empeg. Using a multimeter, check that the empeg's case (when isolated from other metalwork in the car) is grounded to the car body.

We've had people who have had bad ground connections, and their empeg has been getting ground for power from the amp output audio shields. This causes noise and is very bad in general....

Hugo

Tony: Also, check to make sure there aren't any loose wires on the docking connector, or elsewhere in the system.

pim:You mean the AUX and serial connectors? Yes, they are loose. Should I seal them or cut them off?

I think what Tony meant was that the early docking connector plugs came with the wires crimped into place and not soldered. These wires tended to come loose with little provocation. Make sure yours are good and tight, and if not, it is not a difficult job to solder them.

tanstaafl.



"There Ain't No Such Thing As A Free Lunch"

Hi, I've been having the same problem with noise. Measured the voltage between the empeg sled (with the audio connection to the amp disconnected) and the amp ground connection and got a reading of 0.05V. Not much, but still something (especially once it's been amplified). Tried changing the length of the amp earth lead to try and get the same resistance and thus avoid a ground loop, but made no noticable difference. Then noticed that the voltage between the empeg case and the empeg earth lead at the back of the connector was 0.038V!! Grounding the case (as suggested by hobbes in October last year) made quite a noticable difference!! Hmmm, is this right, or do I have a dud connection inside my empeg?? Now have a case to empeg earth voltage of 0.006V and an empeg earth to amp earth voltage of 0.010V. And it is still noisey! (just not quite as bad any more). Tried lenghting up the amp earth (by 2 1/2 m!) and got the empeg-amp voltage down to 0.002V, but this made no noticable difference to the noise (well no that I noticed). Hugo, want to get the boys to bring their tool box to the meed in Holland? Oh, the noise I am getting is alternator noise with the motor running, and what sounds like digital noise with the motor off. The amp is mounted right next to the empeg too. Have read Tonys FAQ and the references in it, but haven't found a complete solution yet

(list 6284, Mk1 S/N 00299 4GB blue [for sale]. Mk2 S/N 080000094 6GB blue)

The amp is mounted right next to the empeg too.

This could be the whole problem. Maybe the amp itself is picking up RF noise from the empeg's circuts.

Have you tried physically separating the amp and empeg from each other and from the car wiring?

___________
Tony Fabris

I can take the amp out and sit it on the seat, which is about half a metre (1 1/2 feet for you Americans) away from the empeg, and that doesn't appear to make any difference.

I tryed moving the microphone and serial cables around behind the sled and *thought* it made a small difference when I kept them as far as possible away from the audio cables.

(list 6284, Mk1 S/N 00299 4GB blue [for sale]. Mk2 S/N 080000094 6GB blue)

I assume you are running a separate (fused) power lead to the empeg itself and verify you have a short direct connection to the chassis gnd somewhere in the dash. Avoid grounding near A/C units and dash fans as well. If you already played all the amp and head unit housing gnd isolation games then supply noise is a likely source. Do _not_ single point gnd your amps and head unit and crossovers. Every piece of equipment should have a separate short and healthy gauge gnd (based on it's current consumption). Also, run clean power directly from the battery. You don't need a different run for each piece, but keep the high current and low current stuff on separate runs. Fuse everything, don't catch your carpet on fire because you were cheap and/or lazy.

Additionally, do NOT get those quintuple über shielded RCA interconnects. You want to run unshielded twisted pair in a car (remember the entire car chassis is gnd) no matter what the sales idiot or installer tells you. Using shielded interconnects adds an additional path for gnd currents. You aren't shielding anything, the majority of noise in car audio is conducted not radiated. Considering the entire car is a conductor, people often miss this point.

#080000512 green 12GB

Well said! A lot of good points that I agree with wholeheartedly - especially the silly multi-shield RCA cables. I bought the cheapest ones on the display stand, was careful about the quality of my connections, and slapped it together. No noise!

The one time I had noise was a crackling noise, which turned out to be a broken earth lead in the internal wiring of the unit itself, which when repaired and re-routed, removed the noise. Haven't had a problem since.

One of the few remaining Mk1 owners... #00015

OK, I've seen a number of useful replies to my question. I will

• test whether the empeg case is grounded with the RCA cables off


• try powering the empeg direct from the battery


• try grounding the empeg direct to the chassis


• try a 10A power filter I just bought


• try combinations of the above

I have already made a number of cables I will be able to test with as soon as my empeg is returned from being repaired.

But there's one other quetion on my mind: if I power the empeg directly from the battery, will I need to use a relay for the switched power lead? Otherwise, only the permanent power will be clean; the switched power will not be clean. Or does the player only draw current from the permanent power lead?

But there's one other quetion on my mind: if I power the empeg directly from the battery, will I need to use a relay for the switched power lead?

No, you will still use the ignition-switched wire for the switched power lead. Only the constant-power wire should come straight from the battery. (You do need to put a fuse block on anything coming off the battery, remember. Mine is a weatherproof 20a fuse in the engine compartment, only 6 inches down the line from the battery.)

Just for diagnostic purposes, you can try connecting both leads to the constant battery power and see if that gets rid of your noise. Although I don't expect it would change anything.

___________
Tony Fabris

OK, I've seen a number of useful replies to my question. I will
test whether the empeg case is grounded with the RCA cables off

Yes it was.

try powering the empeg direct from the battery

No change whatsoever.

try grounding the empeg direct to the chassis

No change whatsoever.

try a 10A power filter I just bought

Yes, that's it! It's 100% gone! The power filter is from Freitag Elektronik.
I bought it for € 9 at my local Media Markt store.

try combinations of the above

Not necessary. It's the power filter that does the job.

Tony Fabris wrote:
No, you will still use the ignition-switched wire for the switched power lead.
Only the constant-power wire should come straight from the battery.

For me this translated to: only the constant-power wire should be connected to the power filter.
Oddly enough, disconnecting the the constant-power wire while the Empeg is playing will not stop the player.
So the Empeg can draw its power from the switched-power wire too, which, as it appears, is less perceptive to noise.

There is one other diagnostic method that came to my mind now that I solved the problem:

• Listen to the Empeg using walkman-style headphones.

This would have helped me to find out that my problem was not related to the amp or any cable leading to it.

Hope this helps for Empeg owners with similar problems.

So exactly which power filter did you buy? Sounds like I might have to head down to my local MediaMarkt too, 'cause the other things have all drawn a blank on my unit.

(list 6284, Mk1 S/N 00299 4GB blue [for sale]. Mk2 S/N 080000094 6GB blue)

Oh, and did you hang the Amp off the filter too, or just the head unit?

(list 6284, Mk1 S/N 00299 4GB blue [for sale]. Mk2 S/N 080000094 6GB blue)

So exactly which power filter did you buy? Sounds like I might have to head down to my local MediaMarkt too, 'cause the other things have all drawn a blank on my unit.
Ditto...

Frank van Gestel

I got hold of a 20 A Altai choke, which has a shielded core and separate ground wire (for bodyshell earthing). It's pretty meaty, cost about Fl 25- (GBP 8.00). It has done a truly excellent job of line conditioning. Since Altai are available just about everywhere, if anyone's interested I can get the Altai part number and post it here.

One of the few remaining Mk1 owners... #00015

Greetings!

Is it similar to this device from Crutchfield? I have one, but have not gotten around to installing it yet.

Paul G.
SN# 090000587 (40GB Clear)

From the crutchfield page :


TIP: Sometimes alternator whine can be cured just by topping off the fluid in your battery or properly grounding your in-dash receiver.


Topping off the fluid in your battery??? How's that related to alternator whine?





Frank van Gestel

Something like that, but mine does not go into the alternator (AC) lines. You put it in line with your (rectified) 12V DC feed, whether switched or permanent. Additionally, the one I have is lower current (20A) and it is built in a can, which has a third lead connected to the choke core and the shielding to provide a Faraday cage for any residual field leakage.

One of the few remaining Mk1 owners... #00015

The impedance of the battery varies according to the strength of the electrolyte and electrolyte level. If your battery has a low or dry (!) cell, your battery becomes a rather poor, leaky capacitor. There are various inductors in the charge circuit, and they create a pretty efficient LC filter. If your battery is dying, it changes capacitance and the characteristics of the "filter", so any ripple on the AC lines goes straight out on your 12V DC feed lines, switched or permanent.

One of the few remaining Mk1 owners... #00015

So exactly which power filter did you buy? Sounds like I might have to head down to my local MediaMarkt too, 'cause the other things have all drawn a blank on my unit.

Well, they have three different models, all from Freitag Elektronik. I think they were rated 5, 10 and 20 A, respectively. I was not sure how much the Empeg needed, so I bought the 10A version to be sure. It turned out the smaller model would have been sufficient too, as the Empeg has a 3A fuse.

The 10A version costs fl. 19,95 which is about 9 Euro. It appears the Euro sign was lost in my previous post (although it did show up in preview).

I have also seen a Pioneer 4A power filter at a local small Halfords store. I guess this one should be sufficient too. And it is also a lot smaller than the Freitag one.

And yes, only the head unit needed filtering. I assumed this, because - like I described in a previous post - the alternator whining was also gone when I connect the head unit to the AC adapter.

Slightly strange, though, as the empeg (mk2 I assume you have) has a filter - there's one built into the fuseholder!

Hugo

Is it similar to this device from Crutchfield?

No, the Crutchfield device is connected in between the alternator output lead.

The Freitag device is connected close to the device that needs to be filtered (i. the head unit). It has three wires; one is 12V in, one is 12V out and the third one is ground. The ground wire needs to be connected to the same ground as the device that needs filtering.

If there's any demand I'll dig the filter up and post a picture of it.

Slightly strange, though, as the empeg (mk2 I assume you have) has a filter - there's one built into the fuseholder!

Well, there's no way the filter in the fuseholder can do the same as the Freitag filter.
The Freitag filter has three wires (12V in, 12V out and ground) and the fuseholder only two.

(Yes I have a Mk2)

It can - the empeg choke is unshielded, and hence has no shield ground wire.

One of the few remaining Mk1 owners... #00015

It can - the empeg choke is unshielded, and hence has no shield ground wire.

One of the few remaining Mk1 owners...

The Mk2 fuse holder is external. It definitely does not touch ground anywhere.

Excellent information, as usual, Rob. That's going into the FAQ.

___________
Tony Fabris

It has three wires; one is 12V in, one is 12V out and the third one is ground.

More like the device on the bottom of this page.

Dragi "Bonzi" Raos
Zagreb, Croatia
Q#5196, MkII#80000376, 18GB green

On my Mk 1, the fuse holder and choke are combined in one unit. If you do not have hte same external choke unit, then I would agree - if the holder touched earth anywhere, it would make it pretty useless

Think we are talking at crossed purposes here.

One of the few remaining Mk1 owners... #00015

More like the device on the bottom of this page.

Right, this is how the filter looks. Oddly enough, that URL also has a link to Crutchfield's
How-to Tips that I used as a lead for making diagnostics.

If I follow that diagram, it leads to buying this Crutchfield filter, which, in my case, indeed was the solution.