BMW M5 Forum and M6 Forums banner

1 - 20 of 27 Posts

·
Moderator
Joined
·
8,369 Posts
Discussion Starter #1
I did a search and didnt find anything conclusive.

Question please: I now have a fairly pronounced alternator whine. Noise is present even if the stereo system is off.

Has anyone successfully eliminated the alternator whine noise after they upgraded their amp? Help please as it is starting to annoy me.

By the way, the alternator whine started to appear before I even installed the Alpine PDX5 amp. It started to appear after I installed a temporary subwoofer amp to power my M-Audio subs.

I will double check all my connections, all the grounds for really good grounds, and all the RCA cables for tightness and good connections next weekend.

Notes:

- I used Monster cable XLN RCA patch cables. 3 feet long.
- I used twisted pair speaker cables.
- My power cable is 4 gauge wire and only about 3 feet long direct from the battery + terminal.
- My ground wire is also 4 gauge and only about a foot long.
- Power wire is away from RCA cables and speaker cables.

I am going to try and ground the BMW radio module and Alpine amp to the same ground stud.

I am going back and clean out the chassis ground stud I installed. It is possible I didnt do a very good job removing all the paint before I installed the ground stud.

As a last resort, I will try a ground loop isolator. But I really dont like to use a GLI as all it does is "mask" the problem, it doesnt really eliminate it.

Again, never ending thank you Doug for the great info on how to remove the DSP amp and upgrade to a better aftermarket amp!

I will post pictures soon. Here's a couple for now.
<!-- / message -->
 

Attachments

·
Registered
Joined
·
2,203 Posts
oh no Dan. Sorry to hear that mate, not as sorry as you I guess. (grabs popcorn, waits for Doug to put the cape on and come to the rescue)
Seriously mate, I hope you get it sorted.
 
  • Like
Reactions: whatheheck

·
Moderator
Joined
·
8,369 Posts
Discussion Starter #3
Troubleshooting guide info

I downloaded a couple of great documents off of the internet in helping me troubleshoot the alternator whine noise issue I am having. Thanks to Crutchfield and a couple of other websites for this great troubleshooting guide.

After doing a search here on the M5board, it appears alternator whine is a common problem on our beasts after adding and/or upgrading the stock amp.

There has to be a simple, common fix for this for our beasts as we all suffer the same issue. If anyone has succesfully eliminated the noise, kindly chime in and share.

If not, I plan to go through the step by step procedures shown here on the attachment. There goes my weekend again.....
 

Attachments

·
Registered
Joined
·
6,517 Posts
If the noise started when you installed your aftermarket amplifier, then we can narrow the issue down to something related to that specific device, not just a generic "ground loop issue".

My suspicion is that you need to clean off your ground location better.

A good ground has 3 distinct characteristics:
1. It is solidly attached to the vehicle chassis,
2. It is a bare metal to bare metal connection, and
3. It utilizes a cable that is that same size, or larger, as the power supply cable.

With the exception of number 3, these can be a bit nebulous to define, so let me give you the easiest way to determine if you are likely to have alt whine: resistance measurement of your ground. Basically, you need to measure the resistance between the ground connection on the electronic device and the negative pole on the battery.

A proper ground will measure 0 ohms. Unfortunately, and difference in resistance measurement amongst the various devices will result in alternator whine. This means that even if your installation measures 0 ohms, if the factory installation does not, you will likely have alternator whine.

So, first step is to measure your installation. If it measures 0 ohms, you are as good as can be. If not, fix it :)

Then measure the factory electronics resistance - they all need to measure 0 ohms as well. Head unit, GPS, radio, cd changer, etc, etc ALL need to read the same as your installation.

Hope this helps,

and trust me, ground loop sucks.

Doug
 

·
Registered
Joined
·
1,627 Posts
hmm, i read amp needs to be 3 feet or farther from the radio. Unfortunately I think yours is within 3 inches.

I've fully removed dsp amp and installed JL 300/4 and PPI a600. My amps are under the rear deck. No whine. Hmm.....

I did not know the issue was present with the former amp.

Hmmm- sorry for the useless post- subscibing for now.
 

·
Moderator
Joined
·
8,369 Posts
Discussion Starter #6
Thanks for the great info Doug!

There's my project for the weekend.....

BTW, my CD changer audio adapter cable shipped today from Crown BMW! Finally! Cant wait for it so I can finish this all up.

I will start troubleshooting this audio noise this weekend and report back next week.

Then measure the factory electronics resistance - they all need to measure 0 ohms as well. Head unit, GPS, radio, cd changer, etc, etc ALL need to read the same as your installation.

Hope this helps,

and trust me, ground loop sucks.

Doug
 

·
Moderator
Joined
·
8,369 Posts
Discussion Starter #7
Good point Neil. I read that too somewhere, but come to think of it, the stock DSP amp was right beside the radio module and there was not a hint of noise from the stock original BMW configuration.

But I will try that too as a last resort (relocate the amp).

I will start by cleaning my ground connections and measure resistance.

I'm on a mission to get rid of this noise as I know a lot of members here suffers with it. Wish me luck!

(Yes, the alternator whine noise started after I installed the temporary subwoofer amp. And it never went away.)

hmm, i read amp needs to be 3 feet or farther from the radio. Unfortunately I think yours is within 3 inches.

I've fully removed dsp amp and installed JL 300/4 and PPI a600. My amps are under the rear deck. No whine. Hmm.....

I did not know the issue was present with the former amp.

Hmmm- sorry for the useless post- subscibing for now.
 

·
Moderator
Joined
·
8,369 Posts
Discussion Starter #8 (Edited)
Doug and Neil, I think you folks are right.

It is a bad ground that causes the alternator whine noise I am getting.

The stock BMW bolt that I am using to ground the Alpine amp is not a good ground. Whatever ground I am getting there is what we call here at Boeing which is "incidental grounding". It is a ground source but not designed to be used for equipment grounding as it is not tied properly to the rest of the vehicle chassis.

But the challenge now is - where do I obtain a good ground?'

Should I run a new 4 gauge ground wire from the negative battery pole to the rear frame chassis? Then tap my amp ground from there?

FYI, the DVD player, HD Dice and EQ are all powered and grounded by the stock BMW harness that used to provide power to the DSP amp.

The remote turn on wire is solely connected to the new Alpine AMP.

So I need to learn / figure out where to get the best ground from.

Any inputs from our audio gurus here?

BTW, I am using high quality Monster Cable XLN (extra low noise) RCA patch cables.
 

·
Registered
Joined
·
1,531 Posts
if you unplug the RCA cables from the amp, do you still get the noise?

When you had just the temp sub amp in place, was the whine just in the subs, or all speakers?

Do you still have the temp sub amp in place? what happens if you totally disconnect it?

I'm interested to see what you do to solve it, I have a PPI PCX-440 and PPI PCX-2125 going in once my new speakers arrive, and want to make sure I don't have the same problem. Although, due to the size of the amps, they will have to be mounted far away from the tuner.

Maybe try unbolting your amp and pulling it away from the receiver and see if the whine changes.
 

·
Moderator
Joined
·
8,369 Posts
Discussion Starter #10
The noise started when I a added a temporary subwoofer amp.

The subwoofer amp is now gone.

I chose the Alpine PDX-5 as it is a 5 channel amp.
4 (75W) channels for the mains and one 300W for the subwoofer.
Great powerful amp. Very clean sounding.

I am certain it is a bad ground that causes the whine.

So I now need to find a good ground source and may have to run a separate ground from the negative battery pole.

I will try all kinds of stuff this weekend I will keep you folks posted.

Based on what I've read here on the board, alternator whine is a common problem for folks that have installed an aftermarket amp. And I have yet to read a post saying they were able to competely eliminate it.

I am shooting for success.

Stay tuned!

if you unplug the RCA cables from the amp, do you still get the noise?

When you had just the temp sub amp in place, was the whine just in the subs, or all speakers?

Do you still have the temp sub amp in place? what happens if you totally disconnect it?

I'm interested to see what you do to solve it, I have a PPI PCX-440 and PPI PCX-2125 going in once my new speakers arrive, and want to make sure I don't have the same problem. Although, due to the size of the amps, they will have to be mounted far away from the tuner.

Maybe try unbolting your amp and pulling it away from the receiver and see if the whine changes.
 

·
Registered
Joined
·
6,517 Posts
I'm grounded under one of the plastic nuts in the back.

Looking at your trunk floor there is the part all the way forward (rear of the rear seat) that is attached to the floor. The rest of the pieces can be removed. I pulled up the forward piece, used a wire brush attachment in a drill to polish off the paint, and put my grounds there. 0 Ohms, which means it is part of the frame.

You want your ground as short as possible (mine is about 2'). I've never heard anything about keeping the components apart.

The biggest issue in a good ground is paint removal. No paint, no primer - just metal.

Bear in mind that there are other causes of alternator whine, but ground loop is the single biggest cause...

Doug
 

·
Moderator
Joined
·
8,369 Posts
Discussion Starter #12 (Edited)
My current ground wire is ideal as it is only about 12 inches long and away from any other power, audio, speaker or RCA cables.

It is routed separately from all other cables. ( will take photos soon.)

My first plan of attack is to do a better job cleaning the paint off my existing ground stud, and if that eliminates the noise - problem solved!

If not, I will try other ground sources like the one you suggested below.

If that doesnt solve the problem, I will go through step by step procedures on finding and isolating the culprit.

Thanks!

I'm grounded under one of the plastic nuts in the back.

Looking at your trunk floor there is the part all the way forward (rear of the rear seat) that is attached to the floor. The rest of the pieces can be removed. I pulled up the forward piece, used a wire brush attachment in a drill to polish off the paint, and put my grounds there. 0 Ohms, which means it is part of the frame.

You want your ground as short as possible (mine is about 2'). I've never heard anything about keeping the components apart.

The biggest issue in a good ground is paint removal. No paint, no primer - just metal.

Bear in mind that there are other causes of alternator whine, but ground loop is the single biggest cause...

Doug
 

·
Moderator
Joined
·
8,369 Posts
Discussion Starter #13 (Edited)
BMW Equipment Ground Wire

Question:

Thinking about this issue last night - the noise appeared when I added an aftermarket amp. The only thing that's changed that I can think of from original wiring configuration is - my new aftermarket amp is no longer tied to the BMW equipment stock ground wiring. No longer uses the BMW equipment ground brown 12 gauge wire that used to ground the DSP amp.

The new Alpine amp now has its own separate ground as it needs bigger gauge wire to support the more powerful amp.

So, it is safe to say that it is indeed a ground issue I am having.

Question. For trouble shooting purposes, would be it safe for me to tie the BMW equipment ground (brown 12 gauge wire) to the Alpine amp to see if the noise goes away?

As long as I dont drive the amp to high volume, low volume only - it should be safe to do this?

Lets say the noise goes away, I then found a better ground and use the new ground to eliminate the noise - would it be a good idea to tie the 12 gauge BMW ground wire to the new ground stud I just created?
 

·
Registered
Joined
·
6,517 Posts
Correct - the issue is caused because you have power getting back to the battery through 2 different paths.

These paths do not have the same resistance. And electrons are lazy and always take the path of least resistance. And what connects the devices that have different ground sources? Your RCA cables.

So those lazy *ss electrons follow the path of least resistance and ground themselves by traveling over the rca cables to the better ground.

Anyway, yes, you should be safe using the factory ground and power at low volumes. Remember you are dealing with a 12 gauge wire which is only rated for about 15 amps, or 200 watts TOTAL.

As for tying the 12 gauge wire to the new ground stud, I can't answer you because I don't know how the wiring harness is set up. At minimum if you were to do so you would need to locate the factory ground point and disconnect it...

Doug
 

·
Moderator
Joined
·
8,369 Posts
Discussion Starter #16 (Edited)
Update:

So, this alternator whine noise has been bothering me for a few days now so I did a lot of reading, did a lot of research and asked you folks a lot of questions. I learned a lot about ground loops. But not enough.

So I created a troubleshooting checklist based on what I now know.

FYI, this issue bothered me so much that I decided to go home for lunch today (only 6 miles away from home) and worked on it for a couple of hours to see if I can figure out what the root problem is.

I tried so many things, including grounding the shield of DSP digital coax connectors, grounding the shield of RCA patch cables, hooking up Alpine Amp directly to battery + and -, etc. etc.

Summary: Noise is still there even with all the electronics removed!

Here's my troubleshooting checklist:

1) Remove the fuse that powers the new amp. Amp is now isolated and non functional.
Noise gone?
If yes, noise is being picked up by the new amp. Need to provide better ground.
If noise is still present, go to step 2.

2) Ground the Radio Tuner case to car chassis ground or battery ground. Noise gone?
If yes, noise is being picked up by Radio tuner. Ground tuner chassis.
If no, go to step 3.

3) Unhook original BMW wiring that now powers iPod, EQ, DVD player and Navigation.
Noise gone?
If yes, noise is being picked up by one of the components above.
If noise is still present, WTF!!!!!!!!!!!!!!!!!!!!!

So, all stereo compoents are now removed from BMW stock wiring and I still have alternator noise! WTF!

There is nothing left hooked up except Navigation LCD dumb terminal and alternator noise is still there!!!!!

So, put the thinking cap back on and do process of elimination.

When did noise started to appear?
After thinking about this really hard, noise actually started when I REMOVED THE M-Audio Subs.

When I installed the temporary Sony subwoofer amp to power my new Pioneer Subs with the M-Audio subs still installed - no noise.

Then I removed the M-Audio subs, installed the Alpine PDX5 and bam! Alternator whine present big time.

(Note: I installed a Pioneer 10" shallow subwoofer and removed the M-Audio subs. I will post this upgrade info here soon.)

So thinking of the above - the culprit appears to be the removal of M-Subs!

It makes sense too. Why my friend BMWMPWR doesn't have alternator whine noise even though he has aftermarket amps and aftermarket subwoofers already installed and DSP amp gone? = He still has his M-subs installed.

If I am a betting man, I'll bet BMWMPWR will have alternator whine noise appear once he removes his M-subs.

How come Doug Baker doesn't have alternator noise? He never had M-audio subs to begin with, he still has the Nokia DSP subs installed so there was no change to subwoofer wiring.

So, we need to figure this out.

What can trigger an alternator whine noise by removing the M-Subs and its entire associated wiring?

And what should I try next?

Ground the LCD dumb terminal? That's all that's left out of the stock BMW M- Audio stereo components.

To the audio experts out there - Help!!!!!!!!!!!!!!!!
 

·
Registered
Joined
·
2,203 Posts
Dan
I have removed my M-Audio subs, and don't have whine.
I did have it whilst I had the aftermarket amp as well as the DSP amp.
Removed the aftermarket amp, kept the alpine LAT 5 sub, and no alternator whine.
 

·
Registered
Joined
·
6,517 Posts
As for your situation, what happens when you remove all connections to the amps except power and speaker output (ie. no source)? If you have whine in this case you may want to take your amps back and get new ones as they may have a problem in the input stage.

Once you have established an amplifier with no whine by itself, then you can start hooking up components, 1 at a time, until the issue presents itself. This piece is the problem.

So here is your list of things to do:

1. Disconnect all connections from amplifiers. Reconnect power and speaker outputs only. Jump the remote turn-on to 12V constant to turn the amp on. Confirm no whine. If you have whine, return your amps - and take your car to a professional installer. Solving that type of problem is beyond our capabilities.
2. Remove all connections from your MK4, DICE, etc -- everything except the tuner module and the bordmonitor. Connect your RCA outputs from your radio module to your amplifier. If you have whine, change the ground on your bordmonitor and radio. I'm betting you won't have an issue.
3. Reconnect power and audio connection to the CD Changer / DICE. Confirm you have no alternator whine.
4. Reconnect your bluetooth, etc. Confirm you have no alternator whine
4. Reconnect your MK4. Run around like a madman wondering whether you can live without the Nav unit in your car until you can change the ground on it and the bordmonitor to the same location as your amps...

Doug
 

·
Moderator
Joined
·
8,369 Posts
Discussion Starter #19 (Edited)
Update: Alternator whine GONE!!!!!!!!!!!

First, a big thank you to my friends Doug Baker and Neil / BMWMPWR for all their help. Never ending thank you!

Drove the beast to work early this morning. Since its so quiet out in the road, I listened to my stereo really well in total silence, volume up, volume down, RPM from 1,000 to rev limit....​

Absolutely NO MORE ALTERNATOR WHINE!!!!!!!!!!!!!​

Relocating the rear tweeter high pass filter and its wiring away from power cables and completely cleaning out the ground stud got rid of all the noise.

Stereo is now very clean and very powerful! I am extremely happy with my Alpine PDX5 amp upgrade. Wow.​

I cant wait to hook up my iPod and Dice HD radio back.
BMW CD changer adapter cable arrives today.​

I will post photos soon.​

You all have a great day!​
 
1 - 20 of 27 Posts
Top