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Discussion Starter · #1 ·
I have six pro amps which I use with a Onkyo receiver. I only use the receiver as a prepro. However Ive dealt with severe ground loop issues for years. Iv tried numerous solutions but nothing works.


My question is if I get a prepro with balanced outputs would that end this issue. Can ground loop hum invade a balanced connection? Thanks.
 

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It might and it might not. Unbalanced connections don't guarantee ground loops and balanced connections don't guarantee against them. With a system as complicated as yours I might consider grounding all the chassis directly to earth.
 

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Your local pro shop may carry the EbTech Hum Eliminator oe equivalent. Pick one up and see if that fixes things. Return policies are usually pretty good if it doesn't pan out.
 

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If you have (temporarily) tried a cheater plug on the amp(s) and that did not help then the ground loop is most likely not amp to AVR and chances are balanced would not help.
 

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Quote:
Originally Posted by Swolephile  /t/1519865/will-a-balanced-prepro-be-immune-to-ground-loop-hum#post_24408986


I have six pro amps which I use with a Onkyo receiver. I only use the receiver as a prepro. However Ive dealt with severe ground loop issues for years. Iv tried numerous solutions but nothing works.


My question is if I get a prepro with balanced outputs would that end this issue. Can ground loop hum invade a balanced connection? Thanks.

I get your frustration.


You have correctly surmised that balanced inputs if hooked up right can go a long way to alleviate ground loops.


BTW the correct way to benefit from the balanced inputs you have is to use cables that are made like this:




That said, this does not ensure the end to ground loops.


Balanced inputs like the ones that are no doubt on your amps have a limited ability to reject common mode interference, which is the technical term for the nastieness that we get from ground loops. This can happen if the ground loop is severe, or if the source and the load are on different wiring circuits.


It is also true that the hum that is bothering you is actually coming from some other problem created by grounding.


What have you done to troubleshoot this problem and are you using the right kind of cable now?
 

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^^^ Note if both prepro and amp have balanced connectors the RCA is not needed, just XLR to XLR, but he may have to lift the ground at one end as shown. By default I have always lifted at the driving (source, prepro) end but it should not really matter.
 

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Discussion Starter · #7 ·

Quote:
Originally Posted by arnyk  /t/1519865/will-a-balanced-prepro-be-immune-to-ground-loop-hum#post_24412670


I get your frustration.


You have correctly surmised that balanced inputs if hooked up right can go a long way to alleviate ground loops.


BTW the correct way to benefit from the balanced inputs you have is to use cables that are made like this:




That said, this does not ensure the end to ground loops.


Balanced inputs like the ones that are no doubt on your amps have a limited ability to reject common mode interference, which is the technical term for the nastieness that we get from ground loops. This can happen if the ground loop is severe, or if the source and the load are on different wiring circuits.


It is also true that the hum that is bothering you is actually coming from some other problem created by grounding.


What have you done to troubleshoot this problem and are you using the right kind of cable now?

Ive tried ground loop isolators, Ebtech Hum x, ART T-8 transformer isolator, cheater plug, and rca to xlr cable. Nothing has worked. However the cheater plugs at least decreased the noise.
 

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Does your system have a connection to a satellite dish or regular cable? If so, odes removing the connection to your system have any effect on the hum?
 

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Discussion Starter · #9 ·
Yes it is connected to a dish box. I tried disconnecting it and nothing changed. I also tried connecting a groundloop isolator between the coaxial cable and dish box but nothing changed there as well.
 

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By disconnecting, I take it you mean you removed the cable from the box that ran into your TV or receiver. Well then, what's the simplest configuration that results in no hum?
 

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It takes more than just disconnecting the cable to eliminate ground loop hum. If you live in a house, go out to the dish and see what it's grounded to. If it's grounded to anything other than your earth ground, move it to the earth ground.

Many times dish installers will ground things to the top of the meter, thinking that's good enough. The thing is, if the whole electrical system in a house is grounded to an earth ground and they ground the dish to the top of the meter, then they've created 2 paths to ground.

Eliminate the 2nd path to ground and you'll eliminate the hum.


Take a look at the 2nd post here for slightly more info:
http://www.avsforum.com/t/1254418/how-to-eliminate-ground-loop-hum-from-directv-hddvr



And btw, I had the same problem with verizon fios grounding to the top of the meter instead of the earth ground. They moved it and no more hum.
 

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Furman balanced power conditioners (equitech's technology) have been said to eliminate ground loops. I have the top of the line Furman "pro" unit in my rack at home and it works well... but I have no ground loop to begin with... so I'm not going to claim it works as advertised.
 

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Quote:
Originally Posted by ajax-jp  /t/1519865/will-a-balanced-prepro-be-immune-to-ground-loop-hum#post_24414327


It takes more than just disconnecting the cable to eliminate ground loop hum. If you live in a house, go out to the dish and see what it's grounded to. If it's grounded to anything other than your earth ground, move it to the earth ground.

Many times dish installers will ground things to the top of the meter, thinking that's good enough. The thing is, if the whole electrical system in a house is grounded to an earth ground and they ground the dish to the top of the meter, then they've created 2 paths to ground.

Eliminate the 2nd path to ground and you'll eliminate the hum.


Take a look at the 2nd post here for slightly more info:
http://www.avsforum.com/t/1254418/how-to-eliminate-ground-loop-hum-from-directv-hddvr



And btw, I had the same problem with verizon fios grounding to the top of the meter instead of the earth ground. They moved it and no more hum.
+1 on this.

OP: FYI there is a Sticky called "Hum FAQ", I posted this there, my real world ground issue/solution:
http://www.avsforum.com/t/322698/hum-faq/120#post_17240091
Quote:
Originally Posted by mtbdudex  /t/322698/hum-faq/120#post_17240091


Note:


I posted this response in the "Subwoofers, Bass, and Transducers" forum, http://www.avsforum.com/avs-vb/showt...9#post17154999


but it should be part of this sticky as knowledge base info.
Quote:
Originally Posted by NCARalph  /forum/post/16192447


I recently redid my AV system to use pretty much all HDMI cables and removed some obsolete components. The result was a very annoying hum.



After some isolation, I determined it was originating in the Comcast cable feed and being distributed by the HDMI cables. Putting in a 3 to 2 prong plug to lift the ground from TV (the only component with a 3 prong plug) helped but didn't fix the problem, plus running completely without a ground worried me.



So I got a Jensen Transformers VRD-1FF on ebay, plugged it in, and POOF! the hum completely went away, even at high volume and no input. This has had no impact on the quality of the cable video including the HD channels. I don't use view on demand or any of the premium channels so I can't comment on those.



Worked for me.



NB - Read and follow the directions that come with it!





I had same problem, the cable people did a crappy job with grounding using cheap clamp, it had I think a bi-metallic corrosion going also as well. (wiggly clamp)



Before showing cable install job:






I took the clamp off, went to HD, bought 6' copper wire, attached to inside home copper pipe, actually next to where the 200A main also had a ground wire attached.


Copper wire going into basement shown:






To make matters a little more complicated, my outside faucets are "isolated" and not really connected to my inside pipes, due to my whole home EcoSmarte system, which uses various plastic/assy stuf for flowmeters, electrodes, etc.


So I connected a jumper wire from my inside pipes to my outside pipes, just to have them on the same ground plane.


This pict shows my whole home H20 system, kinda complicated but great H20 for whole home.





I also made sure the OTA antenna ground plane was same datum.


Here is in construction phase showing the home 2 ground rods.





Here is the OTA antenna being correctly grounded to the red circled one, it is visible just past hot tub cement pad.





Showing OTA copper wire on LH going around the corner under deck, while the antenna lighting rod is grounded next to the elect meters.






So, when solving ground loop issues you have to totally trace/follow your elect system and cable/sat/OTA/etc ground points.



For me, no more ground loop issue.


Maybe $12 max.
 

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Let me chime in by saying that Cable and Satellite set-top boxes are notorious for causing all kinds of noise problems with separate power amplification (as Chu Gai already hinted). In many cases, it may not be the ground loop hum, which is a low-level hum. The coaxial cable that plugs into your Cable or Satellite set-top box can radiate noise that is picked up easily by your interconnect cables if they are close enough. Even if the pre-pro and set-top box are turned off, connecting the coax cable to the set-top box completes the circuit, and noise gets generated. If the noise is coming mostly from your tweeters, then try to increase the distance between the set-top box and your interconnect cables. Choosing well shielded cables can help (e.g., Canare LV-77S if you have unbalanced cables) but moving your interconnect cables away from the cable box is the best option.
 

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I think a ground cheat plug will tell you if your problem will be fixed by hum-x.


I ordered a used humbuster from ps audio because my amplifier transformer hum is present on all my different amps and most likely represents a DC offset problem.


I hear the hum in my amp structure and speakers which is not supposed to happen but maybe it does due to my sensitive speakers.


Another option is regenerated AC which will almost certainly solve these sorts of issues more reliably. Of course then the transformer of the regenerator may start to hum.
 

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I know you said you have Dishnetwork but do you have any cable service old or new coming into the house?

If so go to the closest connection point you can to where the service enters and disconnect it from everthing in the house.

I have seen the most bizarre noise issues from cable providers.

I finally up after spending endless hours with support crews from Comcast trying to convince them that they had a bad ground or a serious short somewhere.

I even showed them that when I inserted a ground loop isolator at the dmark the issue went away.

I just left it in-problem solved....

My internet speed improved as well.


http://www.amazon.com/Viewsonics-VSIS-EU-Cable-Ground-Isolator/dp/B0017I3K9M/ref=sr_1_9/187-0924742-5977117?ie=UTF8&qid=1394030282&sr=8-9&keywords=ground+hum+eliminator
 

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Discussion Starter · #19 ·

Quote:
Originally Posted by trans_lux  /t/1519865/will-a-balanced-prepro-be-immune-to-ground-loop-hum#post_24441894


I know you said you have Dishnetwork but do you have any cable service old or new coming into the house?

If so go to the closest connection point you can to where the service enters and disconnect it from everthing in the house.

I have seen the most bizarre noise issues from cable providers.

I finally up after spending endless hours with support crews from Comcast trying to convince them that they had a bad ground or a serious short somewhere.

I even showed them that when I inserted a ground loop isolator at the dmark the issue went away.

I just left it in-problem solved....

My internet speed improved as well.


http://www.amazon.com/Viewsonics-VSIS-EU-Cable-Ground-Isolator/dp/B0017I3K9M/ref=sr_1_9/187-0924742-5977117?ie=UTF8&qid=1394030282&sr=8-9&keywords=ground+hum+eliminator

Yes I also have Time Warner internet at my home. I currently use a viewsonic ground loop isolator.
 

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Discussion Starter · #20 ·

Quote:
Originally Posted by blazar  /t/1519865/will-a-balanced-prepro-be-immune-to-ground-loop-hum#post_24441764


I think a ground cheat plug will tell you if your problem will be fixed by hum-x.


I ordered a used humbuster from ps audio because my amplifier transformer hum is present on all my different amps and most likely represents a DC offset problem.


I hear the hum in my amp structure and speakers which is not supposed to happen but maybe it does due to my sensitive speakers.


Another option is regenerated AC which will almost certainly solve these sorts of issues more reliably. Of course then the transformer of the regenerator may start to hum.

I have cheater plugs now which reduce the hum to a tolerable level but they dont eliminate it. Ive also used a Hum x which did nothing to help the problem.
 
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