# What does a ground Loop isolator do?



## razzNB (Sep 16, 2012)

Technically?

I have some really bad altanator whine and amp turn off pop on the small amp that powers my front speakers. I bought a PAC isolator and installed it and it got rid of all the noise in the system but the tone seems different. It has something to do with the voltage b/c now I have to turn the volume up higher to get the same volume level. So what exactly does it do?

I did not hook up the 2 ground wires in the isolator b/c it worked w/o them and b/c I assume that is for people who blew there pico fuse and its just grounding the RCAs.

Either way it is going to have to stay until I can get this noise out of my system. And it's well with the 10$ I paid for it.


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## ATOMICTECH62 (Jan 24, 2009)

All of the ones that I have seen are just a small signal transformer.The primary to secondary windings will not pass DC so there is zero reference to ground.If they are not of high quality the inductance of the transformer will cause high frequency degradation,phase shifts and less than optimal flat frequency across the audio spectrum.
I avoid using them at all because there is a reason for the noise which should be dealt with.A ground issue or faulty component is the most common problem.


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## Hanatsu (Nov 9, 2010)

Getting rid of the source of the noise or filtering the source of the noise is usually a better option imo. I don't like to put unnecessary equipment in the signal chain. The small ones are transformers as Atomic said ^^


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## minbari (Mar 3, 2011)

as everyone has said. just a simple 1:1 ratio transformer.

good ones are more than $100.


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## razzNB (Sep 16, 2012)

What would be good one?


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## VP Electricity (Apr 11, 2009)

Jensen Iso-Max Ci-2RR. Markertek.com. Flat to damned near DC.


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## fasfocus00 (Apr 21, 2013)

i use to believe in using Ground Loop isolators but i realized they don't really fix anything. it's like getting sliced up with a knife and using a bandaid, it didn't fix the issue it just covered some of it up. most shops offer this b/c finding and fixing the issue cost them too much time and money.


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## VP Electricity (Apr 11, 2009)

I didn't suggest using a GLI, the OP asked what a good one was, so I replied with the best GLI on the planet. You won't have any problems with that GLI. 

Now, 99% of the time, you can get rid of the noise without a GLI, but that wasn't the request


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## minbari (Mar 3, 2011)

fasfocus00 said:


> i use to believe in using Ground Loop isolators but i realized they don't really fix anything. it's like getting sliced up with a knife and using a bandaid, it didn't fix the issue it just covered some of it up. most shops offer this b/c finding and fixing the issue cost them too much time and money.


Yes and no. you shouldn't bandaid the problem, but there is a legitimate benefit to decoupling the DC content between devices and xformers do an excellent job of it

Sent from my motorola electrify using digital farts


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## razzNB (Sep 16, 2012)

I think I'm going to buy this Jensen unit b/c my car (02 miata mx5 lx) is famous for being a electronically hostile environment for sound equipment. I think it has something to do with the battery being in the trunk even though I thought that would be a good thing.

AND...I just don't to mess with it anymore.

One of these Transformers might be good to have around anyway even when I get tired of the car or the equipment. 

Is 150$ the best price I'm going to get? I don't mind throwing down a buck but a buck fifty makes me a little hesitant.


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## VP Electricity (Apr 11, 2009)

List is $200. You're welcome to look. I know of none. And I've never had a noise issue in that car, even with factory HU and Bosectomies.


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## razzNB (Sep 16, 2012)

VP Electricity said:


> List is $200. You're welcome to look. I know of none. And I've never had a noise issue in that car, even with factory HU and Bosectomies.


What would u think would be the culprit and how would I fix it? It is a ground loop I assume since the adaptor worked?

Am i right to assume that It could only be 2 things the head unit (jvc av60 BT) or the amp (vibe lightbox stereo 2 micro)? I do have a sub amp but the noise predates it. The amp is grounded to the negative terminal of the battery. Would running a ground wire from the head to the battery work? My car had more than just whine too. It had a awful turn off pop and even some engine noise.


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## razzNB (Sep 16, 2012)

It also might have something to do with the Bose amps. My hand was too big to unplug them and I didn't want to pay my local shop 45$ an hour to screw with them so they are still there pro bialy grounded to the same wire as the head.


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## LBaudio (Jan 9, 2009)

Dont use GLI, it is only a band-aid and it only masks the problem and not solve it.
Take your time and find and eliminate problem.....

take care of your wiring, use one common point for all negative and positive leads for all equipment including factory HU.


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## chad (Jun 30, 2005)

There is a time and place for transformers, good ones are expensive and it is most certainly NOT a band-aid. 

Every recording you hear has some of the finest gear used in it using transformers. I'd say most recordings we have contain at least a hundred passes through a transformer.

If I were doing an OEM integration the first thing I'd buy would be a set of transformers, needed or not. My time is worth the extra price to not have to **** with the integration. There are also some combinations of gear that simply WILL NOT work without isolation. some older amps ground the shield as opposed to tying it to the center tap of the PS, this will almost always induce a ground loop in even the rest of the gear that cannot be solved without galvanic isolation.


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## chad (Jun 30, 2005)

Why the **** does this forum link to FUSES when I type ground?


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## 14642 (May 19, 2008)

chad said:


> There is a time and place for transformers, good ones are expensive and it is most certainly NOT a band-aid.
> 
> Every recording you hear has some of the finest gear used in it using transformers. I'd say most recordings we have contain at least a hundred passes through a transformer.
> 
> If I were doing an OEM integration the first thing I'd buy would be a set of transformers, needed or not. My time is worth the extra price to not have to **** with the integration. There are also some combinations of gear that simply WILL NOT work without isolation. some older amps ground the shield as opposed to tying it to the center tap of the PS, this will almost always induce a ground loop in even the rest of the gear that cannot be solved without galvanic isolation.


This is absolutely correct--100%. Transformers can be invaluable. I'd even argue that a noise FILTER is more of a band-aid than a transformer. Until all outputs are floating (or balanced) and all inputs are differential, transformers are the best way to get rid of ground loops in your system. Loops are most often NOT caused by a bad power supply ground connection for your amp. They ARE caused by different potential to ground in the input sections of your amps.

Not all GLIs include transformers, though. The ones that are only caps and resistors decouple ground too, but the value of the caps has to be tuned for the input impedance of the next component. I avoid using those, but building components that include this kind of DC-busting circuit is fine.


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## Oliver (Jun 25, 2007)

chad said:


> Why the **** does this forum link to FUSES when I type ground?


Fuses sell for a bit more 



> Andy Wehmeyer They ARE caused by different potential to ground


Let's call noise a curious kid, we'll call the doors of our building paths to ground.

If noise finds and unlocked door they're going in, some paths to ground allow noise to come in.


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