intermittent alternator whine

yargnat · 10-08-2008, 09:12 AM

Hi all,

I've a strange problem. Fitted 2 aftermarket amps about 6 months ago to my car with basic hifi - I'm in the UK, so it's the 6 speaker variant, with no trunk amplifier, so using speaker level outputs from HU

The installation was to was to send the headunit outputs to the input of an Audiocontrol LC8. The output of the LC8 to the input of the front amplifier (DLS A5), and a rear amplifier (alpine)

The DLS is in the trunk, and powered via 8 guage to the battery
The Alpine in the trunk via 8 guage power and located where the cd changer would normally be.
The Audiocontrol LC8 is also in the trunk - in the shallow well next to the nav unit), also connected directly to the battery.

This has been working fine for the last 6 months with no problems. However in the last 2 weeks, I have intermittently received alternator whine through the speakers, which changes as the car rev's. It can happen upon car startup, or it might happen parttway through a journey.
It can be heard both on radio and on the cd/ipod.

If it put the H/U on mute, the noise is still present.
If I unplug the Phono's at the amplifier side, the noise disappears
I suspect faulty hardware - possibly the audiocontrol unit. Anyone come accross this before, and have any strategy for isolating this?

tintivilus · 10-08-2008, 09:16 AM

Do you have any signal cables with metal connectors that might intermittently short to the chassis to make a ground loop? Last time I had a problem like you describe I fixed it by heat-shrinking all the metal RCA connectors.

yargnat · 10-08-2008, 03:20 PM

Quote:

Originally Posted by tintivilus

Do you have any signal cables with metal connectors that might intermittently short to the chassis to make a ground loop? Last time I had a problem like you describe I fixed it by heat-shrinking all the metal RCA connectors.

All connecters are plastic.
I guess I will experiment with the different earth settings on the Audiocontrol unit - it has 3 options - isolated, 200ohm or ground. Not sure what the difference is with each, and the manual is not much help.

parboy · 10-08-2008, 03:38 PM

I also just installed an lc8 and am having the alternator noise as well. I tried all three ground settings on the lc8 and it didn't make any difference. Turning the gain all the way down on the lc8 helped, but did not take it away completely. My next step is to turn the gains down on my amp (zapco dc reference 650.6) and to move my ground from the chassis to the negative post on the battery. I am hopeful that will eliminate the problem. Should take out any chance of a ground loop at any rate.

I am also getting a massive turn off "pop" when the system shuts down. I am using the signal sensing feature of the lc8, but plan to run an actual switched 12v signal and hope that cures that problem. I'll probably tap off the same line I ran my radar detector to, the homelink fuse. That will mean I can't listen to the radio without actually starting the car, but if it fixes the issue I don't really care at this point.

yargnat · 10-08-2008, 04:51 PM

Quote:

Originally Posted by parboy

I also just installed an lc8 and am having the alternator noise as well. I tried all three ground settings on the lc8 and it didn't make any difference. Turning the gain all the way down on the lc8 helped, but did not take it away completely. My next step is to turn the gains down on my amp (zapco dc reference 650.6) and to move my ground from the chassis to the negative post on the battery. I am hopeful that will eliminate the problem. Should take out any chance of a ground loop at any rate.

I am also getting a massive turn off "pop" when the system shuts down. I am using the signal sensing feature of the lc8, but plan to run an actual switched 12v signal and hope that cures that problem. I'll probably tap off the same line I ran my radar detector to, the homelink fuse. That will mean I can't listen to the radio without actually starting the car, but if it fixes the issue I don't really care at this point.

From Audiocontrol docs, the gain on the audiocontrol box should be high, just before clipping, and the gain on the amp should be low. This prevents hiss. For me, I think this made the whine quieter, but I'll do some further testing this weekend. I think this might be different for me because I guess you are using the amp outputs to your lc8.

I don't get the turn-off pop - but I'm using the switched 12v switched signal from the accessory point, so looks like you are going in the right direction there.

parboy · 10-09-2008, 09:26 AM

I'll try turning the gain up on the lc8 again and see what happens. I hooked my laptop up the amp last night and got the gain turned down and eliminated my whine and hiss. I still have plenty of volume control from the factory head unit, so that is good. I will probably still change my ground to the battery just to be certain. You are correct, I have the logic 7 system, so I am taking the outputs from the factory amp and running those into the lc8.

The most interesting thing about all of this: my car has the bluetooth feature. When I hooked the amp up and had the gain set high, that voice control thing was so loud I thought it was going to blow my speakers! Same with the door "gong" or "chime", loud enough to blow eardrums! I had to turn the amp gains down to get that stuff under control LOL.

yargnat · 10-09-2008, 04:19 PM

Quote:

Originally Posted by parboy

I'll try turning the gain up on the lc8 again and see what happens. I hooked my laptop up the amp last night and got the gain turned down and eliminated my whine and hiss. I still have plenty of volume control from the factory head unit, so that is good. I will probably still change my ground to the battery just to be certain. You are correct, I have the logic 7 system, so I am taking the outputs from the factory amp and running those into the lc8.

The most interesting thing about all of this: my car has the bluetooth feature. When I hooked the amp up and had the gain set high, that voice control thing was so loud I thought it was going to blow my speakers! Same with the door "gong" or "chime", loud enough to blow eardrums! I had to turn the amp gains down to get that stuff under control LOL.

On mine, the bluetooth allows you to change the volume from the H/U, so the amp setting is less critical, however, like yours the door gong, and chimes are quite loud. I've tuned my amp so those are at a reasonable volume.

fdiprete · 10-10-2008, 07:54 AM

I am using an EQS, not and LCI but the docs say the same for my unit.
Turn the amp gains all the way down, Turn up the output levels on the LCI.

I had a very slight whine that I eliminated in the above config by turning down the input sensitivity on the EQS.

LonghornDan · 10-22-2008, 05:20 PM

I have a little bit of alternator whine with my Zapco DC650.6 and LC7. I changed from the Isolated ground to 200k and that seemed to help. I still have a little bit of whine. now i just need to get rid of the turn off pop.

parboy · 10-22-2008, 08:20 PM

Longhorn, I had the turn off pop when using my lc8. I had to run an actual 12v switched line to the fuse box and not use the signal sensing of the lc8. After that, no more pop. Only problem is that you have to actually start the car to get the stereo to play. Now that I have switched to the cleansweep I am using the signal sensing and no pop.

LonghornDan · 10-23-2008, 01:12 AM

That is great to know. My car is going into the shop today to have this fixed.

10-08-2008, 09:12 AM	#1
yargnat Enlisted Member 4 Rep 49 Posts Drives: E90 330D M-Sport, Le-Mans Blue Join Date: Apr 2007 Location: UK iTrader: (0)	intermittent alternator whine Hi all, I've a strange problem. Fitted 2 aftermarket amps about 6 months ago to my car with basic hifi - I'm in the UK, so it's the 6 speaker variant, with no trunk amplifier, so using speaker level outputs from HU The installation was to was to send the headunit outputs to the input of an Audiocontrol LC8. The output of the LC8 to the input of the front amplifier (DLS A5), and a rear amplifier (alpine) The DLS is in the trunk, and powered via 8 guage to the battery The Alpine in the trunk via 8 guage power and located where the cd changer would normally be. The Audiocontrol LC8 is also in the trunk - in the shallow well next to the nav unit), also connected directly to the battery. This has been working fine for the last 6 months with no problems. However in the last 2 weeks, I have intermittently received alternator whine through the speakers, which changes as the car rev's. It can happen upon car startup, or it might happen parttway through a journey. It can be heard both on radio and on the cd/ipod. If it put the H/U on mute, the noise is still present. If I unplug the Phono's at the amplifier side, the noise disappears I suspect faulty hardware - possibly the audiocontrol unit. Anyone come accross this before, and have any strategy for isolating this?
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10-08-2008, 09:16 AM	#2
tintivilus Lieutenant Colonel 26 Rep 1,826 Posts Drives: E92 335i Join Date: Sep 2006 Location: Lake County, IL iTrader: (0) Garage List 2007 E92 335i [0.00] 2003 325i [0.00]	Do you have any signal cables with metal connectors that might intermittently short to the chassis to make a ground loop? Last time I had a problem like you describe I fixed it by heat-shrinking all the metal RCA connectors.
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10-08-2008, 03:38 PM	#4
parboy Private 6 Rep 79 Posts Drives: 2009 corvette c6 6 speed Join Date: Jun 2008 Location: North Little Rock, AR iTrader: (1)	I also just installed an lc8 and am having the alternator noise as well. I tried all three ground settings on the lc8 and it didn't make any difference. Turning the gain all the way down on the lc8 helped, but did not take it away completely. My next step is to turn the gains down on my amp (zapco dc reference 650.6) and to move my ground from the chassis to the negative post on the battery. I am hopeful that will eliminate the problem. Should take out any chance of a ground loop at any rate. I am also getting a massive turn off "pop" when the system shuts down. I am using the signal sensing feature of the lc8, but plan to run an actual switched 12v signal and hope that cures that problem. I'll probably tap off the same line I ran my radar detector to, the homelink fuse. That will mean I can't listen to the radio without actually starting the car, but if it fixes the issue I don't really care at this point.
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10-09-2008, 09:26 AM	#6
parboy Private 6 Rep 79 Posts Drives: 2009 corvette c6 6 speed Join Date: Jun 2008 Location: North Little Rock, AR iTrader: (1)	I'll try turning the gain up on the lc8 again and see what happens. I hooked my laptop up the amp last night and got the gain turned down and eliminated my whine and hiss. I still have plenty of volume control from the factory head unit, so that is good. I will probably still change my ground to the battery just to be certain. You are correct, I have the logic 7 system, so I am taking the outputs from the factory amp and running those into the lc8. The most interesting thing about all of this: my car has the bluetooth feature. When I hooked the amp up and had the gain set high, that voice control thing was so loud I thought it was going to blow my speakers! Same with the door "gong" or "chime", loud enough to blow eardrums! I had to turn the amp gains down to get that stuff under control LOL.
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10-10-2008, 07:54 AM	#8
fdiprete First Lieutenant 23 Rep 339 Posts Drives: 2014 512i xdrive Join Date: Jul 2008 Location: NH iTrader: (2)	I am using an EQS, not and LCI but the docs say the same for my unit. Turn the amp gains all the way down, Turn up the output levels on the LCI. I had a very slight whine that I eliminated in the above config by turning down the input sensitivity on the EQS.
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10-22-2008, 05:20 PM	#9
LonghornDan New Member 0 Rep 9 Posts Drives: 2007 E90 335i Join Date: Jun 2005 Location: Austin, TX iTrader: (0)	I have a little bit of alternator whine with my Zapco DC650.6 and LC7. I changed from the Isolated ground to 200k and that seemed to help. I still have a little bit of whine. now i just need to get rid of the turn off pop.
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10-22-2008, 08:20 PM	#10
parboy Private 6 Rep 79 Posts Drives: 2009 corvette c6 6 speed Join Date: Jun 2008 Location: North Little Rock, AR iTrader: (1)	Longhorn, I had the turn off pop when using my lc8. I had to run an actual 12v switched line to the fuse box and not use the signal sensing of the lc8. After that, no more pop. Only problem is that you have to actually start the car to get the stereo to play. Now that I have switched to the cleansweep I am using the signal sensing and no pop.
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10-23-2008, 01:12 AM	#11
LonghornDan New Member 0 Rep 9 Posts Drives: 2007 E90 335i Join Date: Jun 2005 Location: Austin, TX iTrader: (0)	That is great to know. My car is going into the shop today to have this fixed.
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