# e39 - aftermarket stereo upgrade - alternator hiss - HELP!



## reveiler (Apr 30, 2013)

Hi,
I've recently gotten myself a "new" used e39 520 1998. 
First things first right? Car stereo. 
I previously owned the same car, but a 97 model, where I used more or lessthe same audio components. 

The components are as following
Hu is a Pioneer AVH-6300BT (1din with mechanical touch screen) 
Speakers are Focal something something 2 way component, with tweezers in front, without in the back, through 4 different crossover filters
Sub is 2x12" kicker L7
amp for sub is a soundstream tarantula tx2000d
amp for speakers is a unknown ADS 4 channel. 
Can get more specific if needed. 
Signal cables are stinger. 
Battery is a 92Ah gel, located in the trunk along with the amps and sub.

problem is hissing, which varies along with the rpm. 
foot to the pedal = louder higher frequency hissing. 

here's what I've tried

using a different, brand new pioneer HU - no difference
using different grounding points for amps, both chassis and battery - no difference 
unplugging all signal cables from HU - no difference 
unplugging signal cables from sub amp - no difference 
moving the signal cable from sub amp to speaker amp, still disconnected from HU - no difference 
/edit/ unplugging radio antenna from HU - no difference /edit/
unplugging signal cables from both speaker amp AND HU - Hissing GONE 

Whenever I turn down gain on speaker amp the hiss gets lower but always there. When I put my ear close to tweezers when car is standing still I can hear a low but constant buzz sound. 

I'm thinking either speaker amp or alternator. Any suggestions? Gonna try a signal cable outside the car tomorrow to see if there's any difference, as both of em is at left side of car along the side of chassis, beneath doors. 

How often is the problem the alternator itself? 

On my previous car I had no such problems, but instead of focal speakers I used hertz 2 way component in front and Rockford in the back.

Could the new filters in the back be the reason? i never had those in the old car and they came with the car. 

Thank you for any replies


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## xx (Jun 2, 2013)

That's probably a "ground loop" issue (difficult to troubleshoot over the internet but there are a few things people normally try). We hear the sound probably because the amp does not have a floating-type input and there's a potential (ground voltage level) difference at the headunit and the amp further away.

The first step is be sure the headunit is grounded to a nice solid ground chassis (car body metal). Also be sure the amp is grounded to a nice solid ground (car body metal).

If that doesn't work, the second troubleshooting method is .... If you have some extra thick ground cable (maybe 8 gauge type, or a couple of 12 gauge speaker cables tied together to be like 8 gauge), connect it from the ground/chassis of the headunit to the ground of the main amp (ADS). We're basically bridging the ground of both items here.

If that doesn't work... step 3 is buy 2 "ground loop isolators" with the RCA-type/phono connectors if you are using the RCA-type/phono audio cables. Place these isolators near/before the amp, one for the front channels and the other for the rear channels. (Go to images.google.com and enter "ground loop isolator" to see what it looks like.)

Good luck and have fun!


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## reveiler (Apr 30, 2013)

Thanks! Will try. Ill post any updates asap.

/edit/ From what ive read about ground loop isolators is that they only solve the problem temporarily, and should only be used until you find the actual error.

I havent tried any of the solutions yet. Bridge grounding the HU and amp is going to be quite hard, as the HU is in front while the main amp is in the trunk, behind the sub. Mainly because thats where my battery is.

Im going to try double grounding the HU though to the chassis as well. Ive seen quite a few suggesting 8 looping a unisolated speaker cable around the RCA ports on the HU then grounding it on the chassis. But as my HU has the ports loosely connected, like this, and not like this, thats gonna be difficult for me.

Ill get back as soon as somethings tried though.

Edit2: Can a crossover filter be the reason for such noise?


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## reveiler (Apr 30, 2013)

no luck. 
tried grounding HU to chassis. 
tried grounding HU to battery. 
Tried using power to HU directly from battery (same as amp) 
Tried different amp
tried disconnecting speakers, only having one connected. 
Tried RCA cable outside car, apparently the hiss sound comes as soon as the amp gets rca cables connected. doesn't matter if the other end is connected or not. As soon as there's rca plugged into the amp, there's hissing. same goes on the other amp I tried.
battery is 12v when car is dead and 14v or above when running (inaccurate measure tool) 
tried setting amp remote directly to battery

only thing I haven't tried is changing alternator and battery terminals. 

anyone experienced it actually being the alternator?


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## reveiler (Apr 30, 2013)

ordered new alternator and new serpentine belt. 
other suggestions meanwhile are welcome.


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## reveiler (Apr 30, 2013)

changed alternator and serpentine belt, damn speakers are still hissing. I'm starting to hate this car. ideas? suggestions? 

next thing I'm gonna try is putting everything outside the car and see what happens.


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## rstackels (Nov 18, 2013)

i have the same exact problem on my 01 530i it wasn't as loud when i first got the car and then i was looking for the reason my speaker pops when i shut the car off and when i couldn't find it i put all the wires back in and its 3x's worse and now sometimes the front driver side speaker gets quite and then normal again 

if you find out what is wrong i would love to know or what exactly this can bus decoder is and if the 3 series is the right one that should be used?


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## elerner61 (Feb 12, 2011)

How about running a common ground outside the car (just as an exercise) and tie all your grounds there? Also, what about a different RCA cable, something with different shielding?
Here's another, if you've got another HU, wire that up but don't install it in the dash.

Just tossing some ideas out.


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## Cabover1000 (Dec 6, 2013)

Did you ever solve this problem.


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## reveiler (Apr 30, 2013)

Hi, 
actually still workin on it. Because of lack of money theres quite a bit of waiting involved. 
New fuses, fuseboxes, cables, powercables etc on its way in the mail. Gonna change the front speakers as well. And try all new cables. Ill post back if theres any improvement. 
Probably gonna take some time tho, changing suspension as well (not related).

The other day my driver side speaker suddenly died so im kind of hoping that was the culprit. Havent had time to check tho, currently all speakers are disconnected.


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## Cabover1000 (Dec 6, 2013)

That sucks sorry to hear that, im also looking into the same problem. Ill let you know if I find the issue.

Sent from my SPH-M840 using BimmerApp mobile app


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## xx (Jun 2, 2013)

Maybe search "Helix Cap 33". I've seen some people/forums say this small cap behind/on the headunit will help with the noise issue...(?)


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## killer6.7 (Jul 31, 2013)

try a filter cap from the back of the alt. to ground!worked for me


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## bmw330ci04 (Jun 9, 2012)

arent the batteries on the e39 in the trunk? if so, than it wasnt necessary to hook up any wires to the alternator at all (if you did). if you didnt connect to the alternator at all, than there is almost no way you could have alternator whine. your problem is probably running signal cable too close to a power wire, or perhaps a bad ground. try moving wires around and see if that does anything

another way to troubleshoot if by isolating the whine. that means you basically figure out what part in your system is picking up the whine. since there is obviously whine with your radio on, try turning it off. if the whine goes away, than you know its some piece of equipment in your system. then disconnect the rcas from the amp to the radio, leaving them plugged into either or. if you still get hiss, disconnect the rcas all together. if the hiss goes away, you know its the rcas. if not, its somewhere from the amp to the speakers. you continue this until you have basically nothing.

basically with that process, you are eliminating a single part of your system one by one.


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## killer6.7 (Jul 31, 2013)

*Stupid*



bmw330ci04 said:


> arent the batteries on the e39 in the trunk? if so, than it wasnt necessary to hook up any wires to the alternator at all (if you did). if you didnt connect to the alternator at all, than there is almost no way you could have alternator whine. your problem is probably running signal cable too close to a power wire, or perhaps a bad ground. try moving wires around and see if that does anything
> 
> another way to troubleshoot if by isolating the whine. that means you basically figure out what part in your system is picking up the whine. since there is obviously whine with your radio on, try turning it off. if the whine goes away, than you know its some piece of equipment in your system. then disconnect the rcas from the amp to the radio, leaving them plugged into either or. if you still get hiss, disconnect the rcas all together. if the hiss goes away, you know its the rcas. if not, its somewhere from the amp to the speakers. you continue this until you have basically nothing.
> 
> basically with that process, you are eliminating a single part of your system one by one.


Look you dolt did I say any thing about connecting wires to my alt.? NO,I said a FILTER CAP.! some BMW alternators have a filter cap. to reduce alt. whine or hiss.


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## bmw330ci04 (Jun 9, 2012)

killer6.7 said:


> Look you dolt did I say any thing about connecting wires to my alt.? NO,I said a FILTER CAP.! some BMW alternators have a filter cap. to reduce alt. whine or hiss.


PMS much? i wasn't talking to a low level intelligence like yourself. i was talking to the OP (which means not you) and to call me stupid? check your punctuation before you go around calling people that.


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## reveiler (Apr 30, 2013)

Update:

I think it's a bad ground tbh. Been going over the cables a bit with a voltmeter, and there's different ground values on the car compared to the amps. everything is grounded to battery, so amp to battery terminal is good, so is car to battery terminal. But from battery terminal to battery negative post is different. Tried using sandpaper to get the shiny metal to show on terminal. The values still vary, but not as much. Gonna try new terminals today.


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## reveiler (Apr 30, 2013)

Instead of 0,04 resistance like I should, I'm currently getting 1,2. Before sandpaper I had 2,5. Hopefully it's just the terminal being crap.


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## Hd2000fxdl (Mar 18, 2014)

reveiler said:


> Update:
> 
> I think it's a bad ground tbh. Been going over the cables a bit with a voltmeter, and there's different ground values on the car compared to the amps. everything is grounded to battery, so amp to battery terminal is good, so is car to battery terminal. But from battery terminal to battery negative post is different. Tried using sandpaper to get the shiny metal to show on terminal. The values still vary, but not as much. Gonna try new terminals today.


How about the Ground from the battery, not at the battery being you say that's good, but where it connects to the car..

Harry


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