Ground loops and AVR's not having a grounded power cable

[Max2]

It was trouble free and quiet all evening. Thanks for all the help. 

[westom]

 

Something is funky about the cable or the female plug in the wall. I screwed it back on the wall plug all the way down and backed it out just a tad where it was loose and it stopped again.  So was this RFI instead of a ground issue?

First learn how noise gets created. Otherwise continue chasing ghosts. Your conclusions are only from observation. Observation is confounding or useless without first learning these underlying concepts.

Noise is an electrical current. That means a loop. For example A connects to B which connects to C which connects to D which connects to A. Break a connection between C and D. Noise disappears. But that says almost nothing useful. Because noise is generated by a defect in A. Most using observation will accuse C, D or the connection between them. IOW most will use junk science reasoning.

In your case, apparently a safety ground prong is part of that electrical loop. So grounding was accused. I realize this is difficult. Go to an EMC/EMI/RFI conference. Most who attend are bald. No, that is not due to so much head scratching. However one might think so after learning why noise problems such as yours are so complex.

First learn something relevant. Obvservation alone often leads to confusion, misdirection, and junk science reasoning. Observation is only a first step to identifying the "why". Solutions occur long after the "why" is finally determined. First determine what is defective - the why. Only then and much later can a solution be recommended.

Isolators are used by the naive to 'cure symptoms'. Isolators should be used to learn of the many connections between A, B, C, and D that are in that noise loop. Only then can observation start identifying the "why".

At some point, everyone starts scratching their head. Don't worry. That will not make you bald.

Edited April 17, 2015 by westom

[babadono]

I may have got off easy.   I hooked up the new RCA's and it was silent.  I slid my rack back around and boom, it came back. Unhooked everything except the RCA's and it was still there. Unplugged the Direc tv cable from the wall which is across the room and it was gone.  I don't know how it is spilling over, but it was.  The other end of the DTV cable going in to the SAT receiver didn't matter if it was plugged in or not.  Something is funky about the cable or the female plug in the wall. I screwed it back on the wall plug all the way down and backed it out just a tad where it was loose and it stopped again.  So was this RFI instead of a ground issue?

Wow this is/was a weird one. You have a coax feed coming into your room that goes to a DirectTV box. Then out of the box you go HDMI to your AVR. Breaking the path by unplugging the HDMI had no effect but undoing the coax feed fixes it? I'm going to try to remember this one. The DirectTV box only has a 2 prong power cord correct? And the metal of its chassis was/is not touching anything else in your setup?

 Glad all is better Max2

[mark1101]

The trick is to make sure every component is plugged into the same outlet.  There should be only 1 ground.  If you have components plugged into other outlets across the room or on other circuits especially...........you have different grounds.  This can cause the issue.

 

If you have a couple of big power strips you should be able to accomplish this easily.

 

I have 3 Mac amps, 2 QSC amps, 2 processors, 2 preamps, an EQ, 2 CDPs, a tube buffer, a PC, a DVD player, Dish network, and a TV...........all on the same outlet.  3300 watts for the system in my avatar............no issues.

 

I use cheater plugs on every component except 1..........the electrical ground comes from one component and from RCAs only to the others.  The outlet is a GFI (important !!!).  I have never had noise or hum after I set it up this way.

 

Got this idea from NOSVALVES long ago.

[Max2]

 

I may have got off easy.   I hooked up the new RCA's and it was silent.  I slid my rack back around and boom, it came back. Unhooked everything except the RCA's and it was still there. Unplugged the Direc tv cable from the wall which is across the room and it was gone.  I don't know how it is spilling over, but it was.  The other end of the DTV cable going in to the SAT receiver didn't matter if it was plugged in or not.  Something is funky about the cable or the female plug in the wall. I screwed it back on the wall plug all the way down and backed it out just a tad where it was loose and it stopped again.  So was this RFI instead of a ground issue?

Wow this is/was a weird one. You have a coax feed coming into your room that goes to a DirectTV box. Then out of the box you go HDMI to your AVR. Breaking the path by unplugging the HDMI had no effect but undoing the coax feed fixes it? I'm going to try to remember this one. The DirectTV box only has a 2 prong power cord correct? And the metal of its chassis was/is not touching anything else in your setup?

 Glad all is better Max2

 

 

Thank you!

 

That's correct. I cant remember if the DTV box has a ground or not, but I will check tonight and report back.  I am also going to take a look at my dish and see where the ground runs to and if it is still hooked up.

 

 

The trick is to make sure every component is plugged into the same outlet.  There should be only 1 ground.  If you have components plugged into other outlets across the room or on other circuits especially...........you have different grounds.  This can cause the issue.

 

If you have a couple of big power strips you should be able to accomplish this easily.

 

I have 3 Mac amps, 2 QSC amps, 2 processors, 2 preamps, an EQ, 2 CDPs, a tube buffer, a PC, a DVD player, Dish network, and a TV...........all on the same outlet.  3300 watts for the system in my avatar............no issues.

 

I use cheater plugs on every component except 1..........the electrical ground comes from one component and from RCAs only to the others.  The outlet is a GFI (important !!!).  I have never had noise or hum after I set it up this way.

 

Got this idea from NOSVALVES long ago.

 

 

I have that covered.  So if I put a GFI in, run a surge box off of it, use a cheater plug with the amp going through the surge box and you would still be protected? I run HDMI's off all components and only use RCA's from the AVR to the Amp.  I am using a steel server rack for all of my components and wondered if it was absorbing or attracting the unwanted interference.  

 

I do have a spare circuit up in my attic and I may get my electrician friend to put a junction box in and run a dedicated line for the amp or at least get some of these components off of the single circuit, but would that just introduce more issues?

[mark1101]

What I understand with my setup as I described and it being plugged into a GFI..............if one of the components became hot and I touched it and another or became the ground, that the GFI would trip before I got a shock.

 

My system has been setup this way for about 7 years, and I have never been shocked by this setup.

[mark1101]

 

You are always at risk when lightning or other line surges come to test your surge protector, regardless of grounded or ungrounded units are plugged into it.

 

Should people unplug their equipment during a thunderstorm?  I've never known whether this is an Old Wives' Tale.

 

 

When I lived in NY.......never.  Now that I live in Georgia my system is unplugged 100% of the time until I use it.  When I turn things off I unplug it.  It's incredible the damage from lightning down here.  Our electric meter has a protection device on it that sacrifices itself if lightning hits and will protect the large motor devices.  but we lose TVs, clocks, ovens, anything small can be toast.