Alternator noise

**PCYC** · 06-30-2008 08:10 AM

Have any of you had really bad buzzing and alternator noise out of an aftermarket HU. I have tried the PAC-1 filter they worked to get rid of noise but cut out to much of the sound quality. iam using the bose amp with bose speakers. a 10in REaudio sub with a USamps amp. the noise gets worse by the day and it sounds like iam gonna blow the speakers...

**04QuattroTurbo** · 06-30-2008 11:16 AM

Alternator whine, right? Does it increase as you increase the RPM's of your engine and decrease as you lower the RPM's? The issue is usually related to the ground. Check your HU and AMP ground wires. Try to use a thicker, shorter wire to ground. <10 gauge or larger, <1 foot, get a good bare metal chassis ground.

**PCYC** · 06-30-2008 05:52 PM

ive got a 4g ground on bare metal. IT is my bose setup that came with the car. Yes it is an rpm noise. I was wondering if anyone fixed the noise from a bose amp with a trick.

**04QuattroTurbo** · 06-30-2008 06:11 PM

Originally Posted by PCYC

ive got a 4g ground on bare metal. IT is my bose setup that came with the car. Yes it is an rpm noise. I was wondering if anyone fixed the noise from a bose amp with a trick.

then maybe relocate the HU ground?

**3.0L AUDI A4** · 06-30-2008 06:52 PM

Check the HU Ground... If no worky then the "amp" in your headunit sending power to your speakers is shot... If it is pioneer.. they suck with audi's...

I just say go back to oem

**PCYC** · 07-01-2008 04:44 PM

I will check the HU ground. But iam sending the signal via line in out(RCA's)... my amp from the HU isn't being used... The bose amp is being used... I doubt it it the HU ground any good places i drilled into metal radio surround. the my meter says its a good ground. i do have a couple other things grounded of this same point. do you think i should separate the HU ground from my other grounds?

**koolade9** · 07-01-2008 05:13 PM

Originally Posted by PCYC

I will check the HU ground. But iam sending the signal via line in out(RCA's)... my amp from the HU isn't being used... The bose amp is being used... I doubt it it the HU ground any good places i drilled into metal radio surround. the my meter says its a good ground. i do have a couple other things grounded of this same point. do you think i should separate the HU ground from my other grounds?

couple quick questions...

1. did you splice out your RCA outs and use the factory low-level output leads?
2. did you ground the bose pin?
3. did you double-check your wiring on #1 above?
4. are you running your sub amp (nice choice w/usamps btw) off a 3rd set of rca pre-outs?
5. and just to clarify, you're hearing alt noise out of ALL your speakers, correct? Even the sub?
6. you mentioned separating grounds...what other devices are you powering?

assuming all the above is well and good, route your ground lead to a better location on the unibody of the car...just cuz your meter reads 0 ohm, doesn't mean it's necessarily a good ground. Also, try grounding the chassis of your headunit as well (which brand/model is it btw?)

Let's start with that and see where it gets you. Respond back if I need to continue troubleshooting steps...

**PCYC** · 07-01-2008 05:57 PM

1. iam using the metra harness it has rca's built in front/rear rcas
2. i dont believe so
3.iam using the pioneer Avic-d3
4. sub rcas from HU to amp, Thank you, US amps are the word of God
5. No not the sub. the noise is specific to the bose amp and its speakers
6. switch ground, two tv headrest monitors, blue tooth module i think that's it.

the noise is always present with the speakers are playing, you can hear it really well if you pause the i pod or cd

I never have wired a german car before and they are electrically tricky. I also need to wire up the dimmer switch any good ideas. I had the car wired like it is for 6 months, it just got worse about two weeks ago

**koolade9** · 07-01-2008 06:03 PM

Originally Posted by PCYC

1. iam using the metra harness it has rca's built in front/rear rcas
2. i dont believe so
3.iam using the pioneer Avic-d3
4. sub rcas from HU to amp, Thank you, US amps are the word of God
5. No not the sub. the noise is specific to the bose amp and its speakers
6. switch ground, two tv headrest monitors, blue tooth module i think that's it.

the noise is always present with the speakers are playing, you can hear it really well if you pause the i pod or cd

I never have wired a german car before and they are electrically tricky. I also need to wire up the dimmer switch any good ideas. I had the car wired like it is for 6 months, it just got worse about two weeks ago

ding ding ding.... we have a winner with #2... It's a feed coming from the bose amp to the headunit...ground that sucker...

for a dimmer switch, what are you looking to dim?

**PCYC** · 07-01-2008 06:15 PM

which is the bose pin? is it on the metra harness
the screen, night day mode basically

**koolade9** · 07-01-2008 07:11 PM

Originally Posted by PCYC

which is the bose pin? is it on the metra harness
the screen, night day mode basically

Make sure it's an illumination wire and not a dimmer wire on the avic, since they work different ways... if it's simply illumination, you should be able to pull a switched ground signal from the red/yellow at the hazard switch, but you'll have to use a relay to make it work since your avic probably is looking for a 12+ signal... for a 12+ signal, you can grab it from the headlight switch (gray wire)... obviously test these before you start wiring

Do you have your factory radio still? it should have the pin-outs on the top of it, and will list "bose pin" along with it's location... you'll probably have to pull it off the back of the harness if the metra one didn't pin that out...

I've only got my rns-e diagram and don't have a picture of the symph II diagram in front of me, and I'm about to leave work so I don't feel like searching... but that should get you started...