Hello all,

I've just spent the greater part of today (6+ hours) attempting to eliminate alternator whine from my sound system, to no avail. It might be due to my total lack of knowledge on the subject as to what causes this phenomenon..

Anyway, here is my my setup:

2 Amps, one in front, one in back. The front one powers my front two speakers and my overhead sound bar speakers (it is an 80W). My rear amp is a 400watt which powers my 12" Sub I have behind my seat. I have the front channel from the empeg going to the front amp, and the rear channel going to the rear amp.

Right now, the two amps are powered via one cable pulled directly from the positive pole on the battery. The empeg is powered via the radio harness that the old stock radio was powered from.

I have tried just about every grounding combination possible. I've grounded to the mesh jumper that was tied to the old stock stereo chassis (which is grounded to the metal Jeep chassis). I've grounded to various bolts throughout the car (that touch the Jeep chassis). I've grounded the amps in the same place, the empeg in the opposite place, I've grounded amps seperately, I've grounded the whole shebang together, all with no luck. MAJOR MAJOR feedback from the Mk2 (Well, the feedback might be a bug in my player, but I still get alternator whine)

I've tried hooking up my old CD player to my system using the same kind of standards, and I still get a whine when the Jeep is powered on (although not as bad as the empeg).

What I basically am wanting to know is, what in the hell am I doing wrong? 8) I've read just about every post on this forum, EVER, and I've even gone back and re-read old posts regarding these kind of things. I've tried just about everything. If anyone could look at the above info, and deduce what I'm doing wrong, I will take you out for beers if you ever are in the DC/Northern VA area :) If you need any more information on top of this, please feel free to ask. I'm going to be checking about very often, seeing as though my entire Jeep is a slew of wires from the dashboard, amps, etc.. And I have a date tonight and no empeg to impress her with!! :(

Anyway, any information would be absolutely wonderful.

Thanks.

(O|||||O)

I don't have a solution to the alternator whine right now but just wanted to check something...

"Right now, the two amps are powered via one cable pulled directly from the positive pole on the battery."

You may have this but the way you said it sounds like you don't have a fuse on the wire to your battery. If you do great, if not, you really, really should get one.

Alex

As for the alternator whine, this url is good reading.....
http://www.avweb.com/articles/altwhine.html

Alex Lear

Hmm. These grounding probs are a poo aren't they?

I had bad a ground loop until I found that my crossover was the source of most of it. I took it out and SHAZAM. it was gone! So it may not be just the amps or the empeg.

do you get whining when you use a source separate to the car, ie. plug the empeg into the AC mains and power up the amps. still whining? then it's within the amp setup. otherwise it may be the supply rail of the head unit (empeg or not).

try just connecting the center pin of the audio cables into the amp. this either gets really good or [u]really[/u] bad. If it gets better it is definitely the grounding issue, if worse there may be a problem with the power supply rail to amps or head unit, either alternator noise or still a loop problem.

also try moving all amps & head unit to one spot, hooking them all up with power and what does it sound like?
The power cable from the battery goes thru the firewall, branches off to the front amp and on to the amp in the back. Have you taken the emepg power from here too? might be worth a try.
do you take ALL your ground cable back to the same point? need that too but preferably with short cables.

Are the amps indirect contact with metal?

how am I going Dominic?

We'll all band together so that ClemsonJeep can impress his date tonight he said stoicly to no one inparticular

Murray 06000047
____________________

Don't know if this is any help, but Crutchfield has a noise troubleshooting flowchart on their site - it may help determine where in your setup the noise is being introduced(it did for me, anyway).

The URL is http://www.crutchfield.com/infolib/S-RCkyOtGtxKN/carindex.asp?id=nonoise&

You may have this but the way you said it sounds like you don't have a fuse on the wire to your battery. If you do great, if not, you really, really should get one.

No, I neglected to mention that. Basically my power is this:

+Current --- [25 Fuse] ---+-------------- <400W Amp>
|
+---- [20 Fuse]-- <80W Amp>


Again, I am a newbie at car stereo installs.. I've only assembled this with little knowledge of what rated fuses I need where, so let me know if I'm doing something crackheaded.

(O|||||O)

As for the alternator whine, this url is good reading.....

If I were an electrical engineer maybe...... ;)

(O|||||O)

I had bad a ground loop until I found that my crossover was the source of most of it. I took it out and SHAZAM. it was gone! So it may not be just the amps or the empeg.

There is a crossover built into the big (400W) amp, which I use.. but to this point I'm only working with the smaller amp powering my front speakers. The rear amp has been completely disconnected during my whole ordeal.

do you get whining when you use a source separate to the car, ie. plug the empeg into the AC mains and power up the amps. still whining? then it's within the amp setup. otherwise it may be the supply rail of the head unit (empeg or not).

This is a test I haven't been able to try yet, as I live in an apartment on the second floor and have no extension cord that long to try this out with. When I head into work Monday I intend to remedy that.

try just connecting the center pin of the audio cables into the amp. this either gets really good or [u]really[/u] bad. If it gets better it is definitely the grounding issue, if worse there may be a problem with the power supply rail to amps or head unit, either alternator noise or still a loop problem

Erum, you mean just the positive leads on the RCA jack? so that the outside is not touching the outside of the jack? Hmm, Ok I'll give this a try tomorrow and let you all know how it goes. 8)

also try moving all amps & head unit to one spot, hooking them all up with power and what does it sound like?

Man that would suck. My cables are under the floormats and there isn't enough room under the front seat for my big amp. I'd have to recut all my cables to move the small amp to the back, and that would mean not only would I have to run the power/ground all the way to the rear, I would have to run the speaker wires all the way from the front (empeg) to the rear (amp) then back up to the front (to connect with the car speaker leads). I donut think that would probably help the situation at all, do you?

do you take ALL your ground cable back to the same point? need that too but preferably with short cables

Yes. I tried every combination possible, from pulling all the grounds to one central location and also by seperating them all apart and trying different places. I assume that when grounding, though, any metal bolt that connects to the chassis of the car would be sufficient. Is this a correct assumption or no?

Are the amps indirect contact with metal?

Actually, one might be. I'll try completely insulating it from the rest of the Jeep tomrrow and post an update.

We'll all band together so that ClemsonJeep can impress his date tonight he said stoicly to no one inparticular

Oh well, too late for that. The date went okay despite the fact that Emmanuel was not able to make it with us. ;)

(O|||||O)

ps: thanks for the suggestions.. lets keep them rollin in people! I'm not putting it back in the dash until I get at least HALF of my feedback whine reduced. :)

Check the guage of the wire which is running from the battery negative(-) to the frame of the car. I had some alternator whine which turned out to be a small (14Ga) guage piece of wire grounding the battery to the frame. If you are drawing 40A through a 4Ga wire on the positive(+) side, no problem; but you must provide an equal current capacity on the negative(-) side. A piece of 14Ga wire won't get it (well, for long anyway). What you are looking to do is provide a current path with the smallest amount of IR drop from one end to the other. I still have a small amount of alternator whine; however, I only notice it when I've got it cranked up during a soft passage. Here's what I ended up doing:

  (+)---4Ga---FUSE---4Ga---(+)
Battery                    Amp
  (-)                      (-)
   |                        |
  4Ga                      4Ga
   |                        |
 Frame                    Frame

It's worth, at least, checking the gauge of wire which is connecting your battery to the frame. Especially since you mentioned running two amps fused for a total of 45 amps (20 and 25); the return path should be able to handle 45 amps.

Technically, yes - althugh you shoudl try grounding everything back at the battery to see if the sound improves...

Done, didn't improve anything.

The negative pole on the battery is connected to the chassis in two locations, one on the engine block, one on the actual body of the Jeep. Very large wires, so I assume it can handle the current load.

(O|||||O)

Ok, for the second day now I've spent upwards of 4 hours working on this mess. This time I've ripped absolutely everything out and rewired it all, making sure the audio cables are coming to/from the amps completely seperated from the power leads.

I've isolated the problem down to the empeg (or my CD player) whichever is hooked up. The empeg itself I think is buggy and I get some VERY nasty feedback whenever it is connected up. This is a hardware flaw I think, and I'm going to send it off tomorrow to hopefully remedy the situation. I've been experimenting with my CD player, though, which also has pre-amp line outs.

Anyway, here is what the situation is. With no RCA jacks going to the amp, with the whole system powered up, I have no feedback, no alternator whine. If I hook the RCA jacks up, I get output from the stereo as well as alternator whine. So basically I'm assuming this means that the OUTPUT from the stereo is where it is picking up the feedback somehow.

What my question now is, what would cause this behavior in a stereo? I have the audio cables seperate from the power cables. I have the stereo grounded to the same place as the amp (right near the amps). The only difference is I am pulling power off of the wiring loom in my Jeep to the stereo, whereas I pull the power directly from the battery for the amp. Could the fact that the actual wires that go to my speakers are also in the same wiring loom as the power to the stereo? That would seem kinda stupid of Jeep to do that if it causes feedback, but oh well.

Any further insight would be helpful. :)

(O|||||O)

Hmmm, in my Jeep (2000 TJ) I get a bit of alternator whine with my current CD player (no empeg yet). I have been blaming it on the Jeep wiring. You might want to try running the main power for your empeg directly from the battery (which I plan to do when I get my empeg) and see if it helps. Or, like someone mentioned just run it off AC to test.

-Mike

Whenever you've got more than one DC component in the car audio system (i.e., more than one separate amp, a separate crossover, etc.), you have the opportunity for ground loops. And I've seen some nasty ground loops that will enhance and amplify the alternator whine. So, as your subject line suggested, you could be dealing with two separate issues here that sound like they're part of the same issue.

Issue 1: Ground loops between multiple components.

Ah, the black magic of 12-volt audio. I'm only just beginning to learn the proper spells and incantations (eye of newt/wing of bat/8-gauge cable/filter that/boil bubble/toil and trouble/run twisted pair/and ground it double).

As I understand ground loops, the idea is as follows: You've got an amp hooked up to the car chassis with X potential to ground. You've got a head unit hooked up with X potential to ground. You've got another amp with X potential to ground. Etc.

All of those X's are going to be slightly different values. And when that happens, power voltage gets carried through the audio circuitry towards the unit with the best ground, causing noise. This isn't always up to you, either, some equipment will have different potentials internal to their circuitry (grrr, I just found this out, one of my amps is this way. Gonna have to ditch it someday).

This gets complicated by the fact that some components have two grounds: The chassis and the ground wire, and sometimes those have two different potentials.

To remove bad ground loops, you might have to insulate every single one of your components from the car chassis (right down to taping the Empeg docking sleeve if necessary), and run all the power and ground wires to the same point using heavy-gauge wire. This is, as you've said, usually very logistically difficult.

Also, check your amps for ground-loop defeater switches/connectors. For instance, some amps have a little switch or connector which changes its ground potential to help resolve ground loop issues. Some amps have two separate grounding screws that you can switch between.

Issue 2: Alternator whine.

Even when you get rid of all ground loops, you can still have some alternator whine on the primary power lead (although the fewer grounding problems, the less noisy this will be).

Even though the Empeg has a small noise filter on it, you might need to noise filter the amps themselves. That's what I've done: I got the heaviest-duty noise filter that Radio Shack makes (20 amps) and put it on my main power lead that I ran from the battery. Everything powers off of that lead after the noise filter. Depending on your amps, you might need to split your power and run multiple noise filters to different amps.

It varies from car to car. I didn't need to do all that on my VW, it only became necessary on my Honda. Probably because of all the additional electronic equipment in that Honda.

There's also the possibility of induced noise in your audio/speaker cable runs. Run some loose RCA cables out away from the other wiring and see if some of the noise is being picked up RF-style from unfiltered wiring running along your floor tunnels.

Finally, you'll want to make sure your amp gains are adjusted down to reasonable levels. Ground loop noise and alternator whine are always present in every car, the only question is to what degree they are present. Even a perfect system has a noise floor, and if you crank your amps up, you will be able to hear that noise floor no matter what. Set your amps so that 0db on the head unit is the loudest you'll want the amps to play during normal listening.

___________
Tony Fabris

This is a really long shot, but something pretty easy to check and correct if necessary.

Double check the integrity of the ground connection between battery and chassis. You said you had ground running from the battery to both engine and chassis... if the ground connection at the chassis is compromised (loose fastener, corrosion or paint under the connecter, etc.) this can set you up for all kinds of weird problems like the radio only works when the windshield wipers are on, or the horn beeps when you turn on the turn signals. It might also cause an enhancement of alternator whine if all your chassis ground reqirements were being met by having to run "backwards" through the alternator ground circuit.

tanstaafl.



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

Wouldn't it be even better to run a cable directly from the battery to the empeg and amps? You can try it quite fast by runnning the cable direct through the air. And if it helps you can put it under the carpet (or whereever you want).

TeeMcBee

Thru the doors too...?? (Kidding)

TommyE

This was meant just to try. You can go either through open door or come in through the windows if you like (But coming in through windows might hang the system )

TeeMcBee

just remember to open the window before putting it thrugh

Mark
wait for mk III with a USB Host/slave
(USB->GPS)(USB->Bluetooth)(USB->You name it)

Edited by Mark Petersen on 25/7/00 02:08 PM.

Don't bother trying to reconnect your power- or your RCA leads. I've tried it all (head unit to loom/Battery, Amp (600W) to battery/chassis and all possible combinations) and had no success (Renault Safrane v6). I even connected the ground and possitive wiring with 10mm2 cabling and the problem still exists. So don't blame your Jeep for this, but blame Empeg. The only thing left to try is to isolate the wiring (power and rca) from as close as possible to (even in..) the Empeg. I wonder why Empeg isn't changing this design since so many customers are bothered with it. Buying expensive filters (estimated 100UK) and/or other technical appliances shouldn't be necessary. It should be in the head unit already. After all, it's not that you can get one with a Big Mac or a pack of cigarettes. My 'old' Sony radio/CD player performs great in the same setting, working on the same Amp. When problems persist, Empeg gets it's product back.

I slightly confused by this as I don't remember seeing any request for support with such a problem. It's true the mk1 was more twitchy than the average stereo for installs, but we *did* change the design and the mk2 is generally very trouble free in terms of audio quality - both from our own experience and the local installers (who've installed more empegs than any other installer in the world!)

Do you have a mk1 or a mk2 unit?

Hugo

Hmm, I don't think I imagined all these simple noise-free installations I've seen. The Mk.2 empeg works exactly like any other car stereo with 4V line outputs, except the noise floor is far better than most.

CCA installed our Mk.2 before we even had a head unit available to test it - a blind install, zero noise. If you need any kind of a filter then that's down to your installation/amps/vehicle/luck-of-the-draw.

Rob

I'm going to go out on a limb and assume that he's got a mk1 - He *can't* possibly be making these accusations of the mk2 - in my experience, and I'm very picky, it's about as noise-free as you can get a head unit...
-mark

...proud to have owned one of the first Mark I units

I assumed he had a Mk.2 since he threw in a comment about returning the player if he wasn't satisfied. Since we haven't sold any Mk.1 players in six months or more, he would have to be a second hand purchaser, and I doubt he could believe we would refund him on second hand goods that were bought privately.

Thanks for backing us up with regard the Mk.2 sound quality - we have had great feedback about the audio quality, from professional reviewers as well as clients.

Rob

we have had great feedback about the audio quality, from professional reviewers...

Names. We need names. And links. I haven't seen the Mk2 reviewed professionally yet. I want magazine names with page numbers, links to pro stereo sites. Come on, where's that marketing machine?

___________
Tony Fabris

I'm waiting for the Car Stereo Review article to come out before mentioning other publications, as they're a bit pushy about getting an exclusive. This will probably be the most critical review we've ever received, since they perform a lot of serious tests, and I haven't even been able to talk to the reviewer! I just hope they "get it".

In the meantime, ZD have been passing players around their various divisions. There will be features on their technology show, their music site and various publications in the near future.

In the UK, MP3 Magazine ran a 4 page review in their September issue. Lots more reviews are in the pipeline.

Rob

I'm waiting for the Car Stereo Review article to come out... This will probably be the most critical review we've ever received, since they perform a lot of serious tests, and I haven't even been able to talk to the reviewer!

Wow, nail-biting time! Cool, I'm glad to hear you've got all that stuff going on in the pipeline. Any chance you'll appear on ZDNet's "Screen Savers" any time soon? That'd be cool. Oh, and if you can't get over to the US for it, I'd be glad to go on the show and demo the unit for you.

___________
Tony Fabris

Is this problem solved jet or do you still have it?

Do you have the same problem with the sony-headunit?
Is there a difference it the engine is running or not?
If this problem occurs only with the running engine it could be the power of the amp which feeds some noise into the system. I had this problem after installing and rewiring a new amp and the Mk2. I installed a filter (like it's delivered with the sony units for example) to the powersupply of the amp and the problem was gone.

The right way would be:
Connect the amp directly to the battery (like you already have done)
Connect the Mk2 to the ISO-connector of your car (perhaps via adapter)
For testing you could try to just connect the important cables (Batt+/Batt-/Amp remote/Ignition sense and the lines)
You could try to connect the unit directly to the battery - to see if the noise comes from powersupply to the Mk2.
Be sure to stop the engine - it could add noise, too.
Stop other electrical components like Nav, too.
You could disconnect any cables used by the Mk2 which you're sure it doesn't need/aren't fed right.
Be sure that the lines are correct and not accidentially crossed.
Disconnect Line In at the Mk2 if you have connected a unit there (just for testing purpose)

Then run the Mk2. The sound should be clear.
Have you already hooked it up at home with volume at 0 db ? Any noise there? That's a good essential proof for the sound quality of the Mk2.

If you still have the noise - try if you can change it's volume/sound by playing with different frequencies of the equaliser.


TeeMcBee
Got my Mk2! # 080000143

Don't know if this is still a problem for you, but this is the best (and simplest) on-line reference I have found on how to troubleshoot these annoying problems.

http://www.audiocontrol.com/techpapers/tech1002.pdf