Understanding Grounding in Audio (Video)

[KSTR]

I would insist on a goal of "unmeasurable ground loop". One should be able to make it as good to stay below noise spectrum of the components used, i.e. under intrinsic noise/hum. It is possible, but usually only in case you have the whole chain under design control.

Amir could test the intrinsic "cross-current susceptibility" of a device by impressing a current (with the 600Ohms output of the AP) between the relevant connectors of the device, doing a frequency sweep and measuring the DUTs output with shorted (or zero signal in case of DAC) input -- also for cables, testing shield impedance --.
The device's own idle noise impressed between different ground points could also be measured and rated. For instance, the 8kHz packet noise (or other USB/internal activity noise) of DACs often appears as a voltage differential between the USB ground and the audio jack's ground, with the device fully floating (USB isolator required).

 

[edechamps]

There's no ground in it's AC inlet. So by design there's no ground loop.

Besides the issue of parasitic capacitance that was just explained by several people, please also consider that ground loops don't have to involve the AC mains. They can appear in any situation in which a potential difference appears between two ground points. That can easily happen if several devices are interconnected in "interesting" ways.

One example I had to deal with was a ground loop involving a PC directly connected via HDMI to a TV, and also via RCA to an AVR, where the AVR also had an HDMI output connected to the TV. This formed a highly audible ground loop involving PC-TV HDMI ground, PC-AVR RCA ground, and AVR-TV HDMI ground. See? No AC mains necessary.

 

[MRC01]

It may, it may not. It all depends on the impedance between the point it connects to earth and the grounding rod in your panel. Take the typical 25 ohm impedance of ground rods in US installations. 120 volts/25 = 4.5 amps. This is not going to trip a 15 amp breaker. ...

Ah, of course. The electricity goes toward the lower voltage potential of Earth, but that path has resistance which determines the flow (current).

 

[Ismapics]

There's no ground in it's AC inlet. So by design there's no ground loop.

Sure, but a user may connect gear to it that does have it, doesn't that ground from the RCA make it there. But anyhow, its a $3600 amp and they did not thing of including Balanced Inputs, Its not in my budget so I don't really care that much, but I wonder why Denon, does not use them in their gear.

 

[B4ICU]

Ground...and Earth. As I've got to the IAF, the first thing that came to me, is what is ground (earth) on an airplane. Even on ground it has rubber tires.
It do have a ground pin that goes to the wall. If that is not moved on the F-15 back of the inlets, when the engines are run, they swallow it. That's the end of both: the engine and the cable.
But what is the ground after the airplane is airborne? So the common say was it has a special panel, with a pot, field with dirt and the main ground wire is simply stuck in.
Well happy audiophiles fellows, its a joke.
Later, when started to do design (on the FCC of the F-16) a guy from GD came over to explain grounding and concepts. For years, the French went with the ground tree approach. it didn't worked as well as required. The Americans, went to the multi ground point. That makes everything that is metal and not signal to ground. AC body, equipment chassis and a ground plate. Still had to be checked and tested by MIL STD 461.
One of the worst is too much ground: is there are more than one ground routes, it may cause a ground loop and noise.
For all that provide special care to ground in the walls, to their main supply, what is that care doe's over your home wall, all the way to the power station? Yes, the last 10' will not do any good, but cost you a lot.

 

[ShiZo]

I do have a commercial-grade isolated ground outlet for my system, a hubbell hbl5262 IG outlet.

I know there are likely to be no benefit to these but I hope there are no downsides to having an upgrade IG outlet.

nice video @amirm, do you know if it's okay to have an isolated ground outlet for my main system? I read it's used for sensitive hospital equipment so I thought surely it at least will not hurt anything while having superior grip.

 

[amirm]

nice video @amirm, do you know if it's okay to have an isolated ground outlet for my main system? I read it's used for sensitive hospital equipment so I thought surely it at least will not hurt anything while having superior grip.

Oh, it can hurt something if not installed correctly!

First, the "isolated ground outlet" does not isolate ground. It still has 3 pins and ground is there as it would normally would. All it has "isolated" is the metal screw that connects it to the housing. Therefore it requires a second ground wire for that.

These outlets are used in commercial buildings with metal conduits that may provide a poor ground (due to high impedance, etc.). By using these outlets, you can have a more stout, dedicated grounding wire to your service entrance safety ground.

In home setting, you don't use metal conduit so their purpose is moot.

If you use these outlets in an outlet box that is metal, you *must* ground the metal box some other way. Otherwise if a short occurs in the outlet box, it can stay energized and cause electrical shock. I *think* you can remedy this by simply connecting the box to the same safety ground as the outlet.

I use commercial rated outlets that have excellent holding ability so if this is all you need, that is the part I would use, not isolated ground.

 

[ShiZo]

Oh, it can hurt something if not installed correctly!

First, the "isolated ground outlet" does not isolate ground. It still has 3 pins and ground is there as it would normally would. All it has "isolated" is the metal screw that connects it to the housing. Therefore it requires a second ground wire for that.

These outlets are used in commercial buildings with metal conduits that may provide a poor ground (due to high impedance, etc.). By using these outlets, you can have a more stout, dedicated grounding wire to your service entrance safety ground.

In home setting, you don't use metal conduit so their purpose is moot.

If you use these outlets in an outlet box that is metal, you *must* ground the metal box some other way. Otherwise if a short occurs in the outlet box, it can stay energized and cause electrical shock. I *think* you can remedy this by simply connecting the box to the same safety ground as the outlet.

I use commercial-rated outlets that have excellent holding ability so if this is all you need, that is the part I would use, not isolated ground.

Now, I'm scared lol. I do have a metal outlet boxes but I do not think it's grounded to it.

At the time I used this as an installation guide.

https://www.psaudio.com/ps-how/how-to-install-a-power-port-ac-receptacle/

 

[PeteL]

Oh, it can hurt something if not installed correctly!

First, the "isolated ground outlet" does not isolate ground. It still has 3 pins and ground is there as it would normally would. All it has "isolated" is the metal screw that connects it to the housing. Therefore it requires a second ground wire for that.

These outlets are used in commercial buildings with metal conduits that may provide a poor ground (due to high impedance, etc.). By using these outlets, you can have a more stout, dedicated grounding wire to your service entrance safety ground.

In home setting, you don't use metal conduit so their purpose is moot.

If you use these outlets in an outlet box that is metal, you *must* ground the metal box some other way. Otherwise if a short occurs in the outlet box, it can stay energized and cause electrical shock. I *think* you can remedy this by simply connecting the box to the same safety ground as the outlet.

I use commercial rated outlets that have excellent holding ability so if this is all you need, that is the part I would use, not isolated ground.

I have a friend that had massive ground induced problems in is house due not to conduits but to the copper water pipes network, after years of troubleshooting, he redid in PVC at high cost, but only solved maybe 30%. It took his neibhor to do the same to finally get rid of it.

 

[dorirod]

Now, I'm scared lol. I do have a metal outlet boxes but I do not think it's grounded to it.

At the time I used this as an installation guide.

https://www.psaudio.com/ps-how/how-to-install-a-power-port-ac-receptacle/

"After the Power Ports were installed we reconnected the equipment, let it warm up for another hour and were delighted with the results."

What the deuce?? $49 receptacles and not even AFCI/GFCI?

 

[ShiZo]

"After the Power Ports were installed we reconnected the equipment, let it warm up for another hour and were delighted with the results."

What the deuce?? $49 receptacles and not even AFCI/GFCI?

I was told it is a rebranded Hubbell HBL 5262. Are they not afci/gfci (no idea what that is but imagine it has something to do with safety).

I wanted the strong grip and an isolated ground (only to find out I shouldn't have an IGR).

 

[wwenze]

But what is the ground after the airplane is airborne? So the common say was it has a special panel, with a pot, field with dirt and the main ground wire is simply stuck in.
Well happy audiophiles fellows, its a joke.

 

[JSmith]

Hahahahahaha... at least they're not too expensive;

http://www.mableaudio.com/en/productview.asp?sid=7292

http://www.mableaudio.com/en/productview.asp?sid=7293

http://www.mableaudio.com/en/productview.asp?sid=6036

Odd as that site sells many quite cheap items.



JSmith

 

[lurkera]

With unbalanced headphone connections:

1. On the amp end, is it not technically balanced, that is, the ground doesn't go through the chassis? If not, is it not trivial to do this?
2. Are balanced cables/connectors for headphones unnecessary if the above is true, because headphones should have no significant parasitic voltage?

 

[amirm]

2. Are balanced cables/connectors for headphones unnecessary if the above is true, because headphones should have no significant parasitic voltage?

They are not necessary for fidelity. However, there are balanced outputs on amplifiers that require balanced connections on the headphone to produce more power. So you need it for that, but nothing else.

 

[amirm]

Adding on, since headphones are not ground referenced, by definition they are "balanced."

 

[B4ICU]

I've seen so many fancy power cords, claim for improving sound and cost an arm and a leg. Well, when I hear that claim, to charge $1,000 for a 1.5m power cord, I kind of wonder, if it would pass the tea test:
A. Boil a kettle of fresh tab water, with that $1,000 power cord and make a cup of tea (A).
B. Spill the water, pour some from the tab, and boil it again with the original $5.- power cord and prepare another cup of tea (B).
Now, sip some of each and tell if the first cup of tea (A), taste any better than the second cup (B), prepared with an ordinary $5.- power cord.
If it doesn't taste any better, you just spent $995.- for nothing. I'll put my money that the tea will taste the same.
I also wonder, if Mr. Amir could run a test to see what is measured difference between the two.

 

[wwenze]

It will probably melt and you will be smelling the rubber. Kettle requires C15 connector.

 

[JSmith]

Kettle requires C15 connector.

Some audio products use this C7 connector or a C5...

It's always been a joke in audio and tech forums... like a power chord needs a good kettle cord to sound good.

I don't think all kettles are equal either from place to place;

https://www.selby.com.au/cables/pow...v-10a-mains-power-lead-cable-cord-iec100.html

None of this negates the joke about calling power cords for audio products "kettle cords".



JSmith

 

[pma]

I am afraid that all this popular amateur debate on "Understanding Grounding" brings only more confusion into amateur public. We can see mix and mismatch of safety ground, signal ground, chassis and even Earth. The laic equalization like ground = Earth.
It may tend to become dangerous, as we come from different parts of world with different mains networks and safety standards. To understand the differences, one might like to see this study on Earthing systems worldwide

https://www.studiecd.dk/cahiers_techniques/System_earthings_worldwide_and_evolutions.pdf