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Cheap fix on Ground Loop


derrickdj1

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Since I added the bass shakers and another amp in the system I have had a ground loop hum.  Sometime the humming is noticeable and at other times not to noticeable.  Someone in another thread said he found a cheap fix that got rid of most of his hum.  I had a hum another time and people recommend , I think autoformer which cost a bit.  Today I got this device for around $ 6 from ebay and so far it is wonderful.  The hum is completely gone.  It did take about 30 seconds to install.  This was cheaper an easier than changing cable, outlets and the tedious job of trying to eliminate  the hum.

 

http://www.ebay.com/itm/RCA-NOISE-AUDIO-FILTER-GROUND-LOOP-ISOLATOR-HUM-KILLER-/400231421249?pt=US_Car_Audio_Video_Interconnect_C

Edited by derrickdj1
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The problem in the system is the Acurus amp and subs.  Take one or the other out and the problem goes away.  I put this little thing between the AVR LFE/sub out and connected it to the sub cable that are split: a Y connector off the sub/ LFE with one limb to subs rca cable and the second limb to the shaker sub cable.  This way the shakers are not touched by auto EQ/PEQ.

 

The hum is usually caused by some of the high current stuff in the system in my limited experience.

Edited by derrickdj1
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The cheater plugs are good for isolating a ground loop problem, but they should never be used as a permanent solution. Doing this defeats the safety ground and exposes people to the danger of an electric shock in the case of malfunction of any piece of equipment in your system.

 

People that don't know what they are doing need to stop posting this kind of crap. Lives are potentially at stake here. Use the device mentioned in the OP, which appears to be an isolation transformer, or something similar.

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Don,

Are you bit of an alarmist? In an audio/video system the inter-connecting cables pass ground from one device to the next....as long as one device has an earth ground they all have earth ground...the added 3 wires power cable is what completes the loop! The only way a piece of gear could become a danger is if the inter connecting cables either went up in smoke or were disconnected. Yup using cheater plugs does lower the safety margin a minute amount but geezzzz it's not as big of a deal as you're making out to be...

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Josh my "personal" preferred method is no earth ground at all...I use GFI protection which IMHO is about as safe as safe can be.

It really doesn't matter which device has the 3 wire power cord. If one of the components happens to be point to point wired that is the piece I would earth ground.

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Agreed NOS.

 

You know what's funny, if you go to your breaker panel in your house, open up the door and then open up the thing where you can see the wiring that goes into all the breakers, and to the ground bus, you'll see something funny.

 

Black = Hot

White = Neutral

Green = Ground

 

The white and the green are connected to the same ground bus. If some piece of equipment on that circuit is inducing current onto either neutral or ground...this can be a source of hum that is heard. And it will effect EVERYTHING on that panel. Some stuff just doesn't care.

 

Now, I'm not an electrician. So this is just friendly advice and steps I've taken to avoid ground loops in my ham radio equipment. It isn't the only solution. It is 1 step of a very frustrating process to eliminate background noise, hum, etc.

 

The real solution is getting current off of neutral and ground. GFCI outlets pop when there is too much current on ground. Breakers do the same thing. Once the amperes get past a certain threshold, the circuit opens.

Edited by Beechnut
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White is always loaded by the current draw from black, so white is not necessarily zero volts, it's just the opposite of black. Due to resistive losses across the power system and cords, there's a slight fluctuating voltage between white and ground. This is why green ground is used, it's a separate ground which has no load placed upon it.

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I have used the cheater plug to help diagnosis the problem.  It made the hum less but did not eliminate it completely.  This is the 2nd day with the isolator and it is completely gone.  The point is I and others have spent a lot of time trying to get rid of this problem and the cheap but, safe fix appears to be a solution that works and takes less than a min to do.

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Don,

Are you bit of an alarmist? In an audio/video system the inter-connecting cables pass ground from one device to the next....as long as one device has an earth ground they all have earth ground...the added 3 wires power cable is what completes the loop! The only way a piece of gear could become a danger is if the inter connecting cables either went up in smoke or were disconnected. Yup using cheater plugs does lower the safety margin a minute amount but geezzzz it's not as big of a deal as you're making out to be...

 

It really is a big deal - that is, if you value your life or the lives of your family. Grounding through interconnects is definitely not a good idea. I'm going to say it again: use cheater plugs only as a diagnostic aid, then remove them and fix the problem properly.

 

 

 

Josh my "personal" preferred method is no earth ground at all...I use GFI protection which IMHO is about as safe as safe can be.

 

This is a good, safe method. The NEC preferred method for GFCI connection is 2 wire ungrounded. However, the fact that a ground loop occurs is evidence that conventional 3 wire safety ground type circuits are in use.

Edited by Don Richard
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You know what's funny, if you go to your breaker panel in your house, open up the door and then open up the thing where you can see the wiring that goes into all the breakers, and to the ground bus, you'll see something funny.

 

Black = Hot

White = Neutral

Green = Ground

 

The white and the green are connected to the same ground bus. If some piece of equipment on that circuit is inducing current onto either neutral or ground...this can be a source of hum that is heard. And it will effect EVERYTHING on that panel. Some stuff just doesn't care.

 

Now, I'm not an electrician. So this is just friendly advice and steps I've taken to avoid ground loops in my ham radio equipment. It isn't the only solution. It is 1 step of a very frustrating process to eliminate background noise, hum, etc.

 

The real solution is getting current off of neutral and ground. GFCI outlets pop when there is too much current on ground. Breakers do the same thing. Once the amperes get past a certain threshold, the circuit opens.

GFCI's are for personal protection. BREAKERS are for conductor protection.

A GFCI is VERY much different than a circuit breaker. A circuit breaker opens when there is an overheating of the conductor (dead short); a GFCI opens when it senses that current is going somewhere other than the return on the neutral conductor such as to ground through a human.

Electricity follows the path of least resistance and the fact that all of your grounds and neutrals are bonded (or should be) at the panel is normal and would not contribute to this problem you are having.

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You want all of you equipment to have a single path to ground. When you use 3 prong wires on several or all items, this creates multiple paths to ground, thus inducing a ground loop.

 

So when using them, you have to think about the entire circuit and place them strategically. Don't use them on ALL items.

 

Derrick, that item you put up doesn't call itself an isolating transformer, but I think that is what it is. Basically its and AC/AC transformer, which because of it's very makeup, the DC hum doesn't make it through the process.

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I am getting one of these for my sub, it adds a hum when the TV is on, used cheater plug to isolate but don't want to chance as I just paid a bunch to have it fixed, I have had bad luck using RCA ground loop filters as they reduce the band width of the signal. I will let you all know if it works like it says it does when it comes in.

http://www.ebtechaudio.com/humxdes.html

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You want all of you equipment to have a single path to ground. When you use 3 prong wires on several or all items, this creates multiple paths to ground, thus inducing a ground loop.

 

I thought you knew what you were talking about until you posted this. :)  That's not how it works.  You're confusing cause and effect.  Running everything to a common ground is an easy way to make sure you don't have one in car audio, but if all your grounds have the same POTENTIAL, you don't have a ground loop.  Not grounding at all isn't the proper answer.  

 

Typically the biggest risk of getting one is when you are using multiple circuits.  Sometimes it can be fixed simply by balancing loads better.  Also if everything is set up well but then you introduce a coax with a ground you can get it.

But yeah if you have two circuits with different potentials and you use three prong plugs and interconnect them all, you will probably get a ground loop. Using three prong plugs isn't why you got it though, it's because your two circuits have different potentials to ground. You should be able to use three prong plugs on everything.

Edited by MetropolisLakeOutfitters
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Don,

Are you bit of an alarmist? In an audio/video system the inter-connecting cables pass ground from one device to the next....as long as one device has an earth ground they all have earth ground...the added 3 wires power cable is what completes the loop! The only way a piece of gear could become a danger is if the inter connecting cables either went up in smoke or were disconnected. Yup using cheater plugs does lower the safety margin a minute amount but geezzzz it's not as big of a deal as you're making out to be...

 

It really is a big deal - that is, if you value your life or the lives of your family. Grounding through interconnects is definitely not a good idea. I'm going to say it again: use cheater plugs only as a diagnostic aid, then remove them and fix the problem properly.

 

 

 

Josh my "personal" preferred method is no earth ground at all...I use GFI protection which IMHO is about as safe as safe can be.

 

This is a good, safe method. The NEC preferred method for GFCI connection is 2 wire ungrounded. However, the fact that a ground loop occurs is evidence that conventional 3 wire safety ground type circuits are in use.

 

 

 

 Good grief.....show me the statistics that support your claim of extreme danger............for instance back in the day that high voltage tube electronics ruled the day not a single device came equipped with a 3 wire grounded power cord.... show me the statistics to support large numbers of death by electrocution from such devices.

 

   Again I'm not arguing the fact that a grounded power cord adds a very small degree of safety....but to state that running without a ground is a sure fire way to death is just silly! The truth is the chances of harm are about a million to one....

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