ground loop

So I was wondering if there is already engine whine in the audio system, how does adding more grounds to the head unit help?

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Mark "Hamzter" Cinense
1991 Infiniti G20 w/JDM SR20DE
Eclipse CD8445
MTX Thunder 684
Polk DB6750
Polk DB6500
Optima Red Top in the Trunk

It doesn't necessarily.  What helps is getting all system grounds at the same potential.  It's not about "adding" it's about "improving."

Some head units introduce ground loops no matter what you do and must simply be replaced.

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I am having a hard time believing that a quality Eclipse HU (CD-8445) would introduce noise into the system.

The original ground was connected to the chassis = noise. Then I moved it to the harness = noise is significantly less, but nonetheless still present and still in conjunction with acceleration.

When I installed my new alternator, since it needed replacing, I did the BIG 3 upgrade since I was there.

Engine noise still present...



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Mark "Hamzter" Cinense
1991 Infiniti G20 w/JDM SR20DE
Eclipse CD8445
MTX Thunder 684
Polk DB6750
Polk DB6500
Optima Red Top in the Trunk

You say you installed a new alternator.  Try improving the connection between the alternator's case and the chassis.  And yes, even an Eclipse can be defective.

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Support the12volt.com

DYohn] wrote:

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You say you installed a new alternator. Try improving the connection between the alternator's case and the chassis. And yes, even an Eclipse can be defective.

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I installed and additional ground on top of the original ground. Would this cause a G-loop?

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Mark "Hamzter" Cinense
1991 Infiniti G20 w/JDM SR20DE
Eclipse CD8445
MTX Thunder 684
Polk DB6750
Polk DB6500
Optima Red Top in the Trunk

Did you try connecting the ground directly to the alternator housing?

Have you measured the resistance between your ground points with an ohmmeter?

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Support the12volt.com

DYohn] wrote:

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Did you try connecting the ground directly to the alternator housing?

Have you measured the resistance between your ground points with an ohmmeter?

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yes

here is what I have as follows:

Battery - to chassis = .010
Grounds to Amp - = .003
Alternator - to chassis - .001
chassis to engine = .000

with this said, I think the head unit might be toast. reason I say this is that when I turn the volume from 01 to 00 I hear a little faint pop sound. This is with my amp gains turned 3/4 or all the way down to 0.

What do you all think?

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Mark "Hamzter" Cinense
1991 Infiniti G20 w/JDM SR20DE
Eclipse CD8445
MTX Thunder 684
Polk DB6750
Polk DB6500
Optima Red Top in the Trunk

Yes, those are good ground return readings.  You should have no ground loop issues with those numbers.  If you have noise in your system there are still several things you can check, but unfortunately the most likely is the head unit.

-edit- did you measure resistance between your HU ground and the alternator ground?

Other things you can check: integrity of RCA cables; speaker wire grounding out or bad speaker (only an issue if the noise is in one speaker but not others); routing of RCA cables in relation to any high-energy systems in the vehicle; ignition system noise.  Ignition system (or engine ECU) noise is by far the hardest to find and the hardest to fix.  If you change your HU and your RCA cables have been eliminated as a cause, it might be an issue with the vehicle.

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Support the12volt.com

I am now looking for a new Headunit...

The only thing I am thinking about is whether I should with another Eclipse or Kenwood Headunit. I have Kenwood in the Subaru.

The Eclipse is in the Infiniti G20 1991...

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Mark "Hamzter" Cinense
1991 Infiniti G20 w/JDM SR20DE
Eclipse CD8445
MTX Thunder 684
Polk DB6750
Polk DB6500
Optima Red Top in the Trunk

Before you jump on the headunit, what about the rest of the system? Are you using amplifiers in this system? Where are they grounded to? Is there a RCA cable that is pinched?

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Top Secret, I can tell you but then my wife will kill me.

forbidden wrote:

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Before you jump on the headunit, what about the rest of the system? Are you using amplifiers in this system? Where are they grounded to? Is there a RCA cable that is pinched?

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negative... RCAs are good...

I am running MC 201XLNs to the back and 101xln from the Electronic Crossover. EC is new and amps work fine.

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Mark "Hamzter" Cinense
1991 Infiniti G20 w/JDM SR20DE
Eclipse CD8445
MTX Thunder 684
Polk DB6750
Polk DB6500
Optima Red Top in the Trunk

My bet is that you have a huge difference in potential between all the amps, the crossover and the head unit. List all of the equipment, model # etc. how they are installed, where they are installed and we can go forth from there. To me this is indicitave of a install related issue or a bad component further down the line. Lots to go over yet before you run out and purchase a new cd player. (try a new Eclipse though and if you still have noise, you know it is not the head unit - the wire harness is the same for all units over the last 6 years or so).

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Top Secret, I can tell you but then my wife will kill me.

forbidden wrote:

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My bet is that you have a huge difference in potential between all the amps, the crossover and the head unit. List all of the equipment, model # etc. how they are installed, where they are installed and we can go forth from there. To me this is indicitave of a install related issue or a bad component further down the line. Lots to go over yet before you run out and purchase a new cd player. (try a new Eclipse though and if you still have noise, you know it is not the head unit - the wire harness is the same for all units over the last 6 years or so).

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sure... here it goes:

Eclipse CD-8445 to
Memphis Audio 16-X03 3 way crossover to
MTX 684 4 Channel amp powering Polk DB6750s Mids and Tweets
MTX Thunder 1500dx powering 1 Infinity Perfect 12.1
1 Farad cap connected to the 1500dx

Sir-ECL1 from CD-8445 Headunit.

I am using Monster Cable 201xln to the electronic crossover and 101xln from the crossover to the amps respectively.

I am not a pro installer, I am a hobbyist as my real job is computers. I get into the electronics part as a hobby because my real job does not allow me to play with electricity.

so any help and education is definitely welcome.

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Mark "Hamzter" Cinense
1991 Infiniti G20 w/JDM SR20DE
Eclipse CD8445
MTX Thunder 684
Polk DB6750
Polk DB6500
Optima Red Top in the Trunk

Ah.  That crossover could be the culprit as it is also a line driver and it is way more likely to be bad than you HU.  Make sure your ground for the HU and the crossover is the same, and make sure you have CAREFULLY gain-matched the HU output to the Xover input and the amps to the Xover outputs.  Indeed, I suggest the next thing you should try is to take that out of your signal path completely and run directly from the HU to your amps and see if it helps.

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Support the12volt.com

DYohn] wrote:

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Ah. That crossover could be the culprit as it is also a line driver and it is way more likely to be bad than you HU. Make sure your ground for the HU and the crossover is the same, and make sure you have CAREFULLY gain-matched the HU output to the Xover input and the amps to the Xover outputs. Indeed, I suggest the next thing you should try is to take that out of your signal path completely and run directly from the HU to your amps and see if it helps.

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Good point and normally I would agree with you since I have not thought that the 8volt output would have made an issue. I am not sure if I can adjust that. I will have to read the op manual.

The only thing is that I had a Coustic Electronic crossover before I had replaced it with the Memphis Audio EC. I recall that I had engine noise when I first installed this headunit, but was not sure if it was my battery run to the trunk or my alternator. When I initially installed my HU I did not have any amplifiers installed except the OEM amplifiers were inline as high level inputed from my speaker output. I am wondering if that is somehow the culprit. I removed the rear oem amp and everything is on its own separate run.

So anyway I did run a seperate ground from the HU to the spot where the EC is grounded in the trunk. Eclipse TS told me to do that. AAMOF, they told me to run another ground in conjunction with the one I just ran to another location, ie chassis ground close to the HU.

that is why my original question is does adding more grounds create a Ground Loop?

this has got to be my most challenging install.

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Mark "Hamzter" Cinense
1991 Infiniti G20 w/JDM SR20DE
Eclipse CD8445
MTX Thunder 684
Polk DB6750
Polk DB6500
Optima Red Top in the Trunk

ok... sorry for not listening to you guys, my RCAs going to the amp from the crossover was the culprit. Not to mention that my Crossover was somehow on top of the flippin' positive cable from the front. about 98% of the noise was coming from this.

I will be rearranging my layout. However I am still getting a little alternator noise.

All my grounds are dead on potential.

Without the car on 12.0v across all grounds
With the car on 14.26 across all grounds

any suggestions?

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Mark "Hamzter" Cinense
1991 Infiniti G20 w/JDM SR20DE
Eclipse CD8445
MTX Thunder 684
Polk DB6750
Polk DB6500
Optima Red Top in the Trunk

Eliminate the crossover, chances are you totally do not need it and it more than likely is the source of the noise as I first suspected.

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Top Secret, I can tell you but then my wife will kill me.

I have never used a ground loop isolator. Do they work?

I mean really?

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Mark "Hamzter" Cinense
1991 Infiniti G20 w/JDM SR20DE
Eclipse CD8445
MTX Thunder 684
Polk DB6750
Polk DB6500
Optima Red Top in the Trunk