Understanding Grounding in Audio (Video)

[JSmith]

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

https://www.audiosciencereview.com/...g-grounding-in-audio-video.21360/#post-708889



JSmith

 

[B4ICU]

Lets say, you buy a new sound system for $30,000.- bring it home, and its has a ground noise. What do you do?
A. Return it to the dealer?
B. Get a certified electrician to try fix the problem.
Now let's say that you own already that system, it sound clean and than one day toy move to a new place. It gets noisy you go to plan B.
Or, If you owned a sound system, that sounded clean and you upgraded it, you go to plan A.
Ground noise and other related to power, may be get over, with a 1:1 isolating transformer, with a passive or active power filter (reconstructing...)
The conclusions are simple:
A proper power wiring in your residence is essential. If you don't, get a professional to fix it.
If power is fine but the equipment is not, exchange of fix the faulty component.
Who would fidle around with it's home grounding?
In my country (Israel) it's illegal. Well, our Prime Minister, is also a Crime Minister (3 charges so far). So who cares about ground?

 

[Lambda]

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?

 

[dorirod]

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).

No AFCI (<$30) and GFCI (<$15) have buttons, looks like this:
https://www.eaton.com/us/en-us/products/residential/afci-and-gfci-requirements.html

What you got is a lot more expensive and provides fewer features/protection. I couldn't say how safe it and the installation instructions are (you'd need an electrician).

 

[Lambda]

https://simple.wikipedia.org/wiki/Residual-current_device
If this is not mandated standard here you live i would highly recommend getting one installed.

A central one at the barker box and and more sensitive ones per circuit save a lot of headaches!
Not only can they save lives but you can use them as troubleshooting device.

if the they trip a devices is putting current on the ground. this can be unsafe but it also causes noise in your audio system. so its good to know!
Or ground and Neutral are connected behind the device can also make them trip. (also bad)
And you can use a tool like this to check if the outlet is properly grounded https://www.amazon.com/Receptacle-Tester-Klein-Tools-RT210/dp/B01AKX8L0M

 

[bigguyca]

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

This "study" appears to be from the year 1995. Have you verified that all of the study, except for the historical elements, still completely applies worldwide? Did you just post this item for fun or is there something to learn about the electric grid in today's world?

Changes in technology are creating changes even among the stodgy electric power companies, at least in the U.S.

 

[bigguyca]

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.

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.

In some areas of buildings where sensitive electronic equipment is installed, such as computers, it is considered an advantage to run a separate ground wire back to the service entrance instead of using the general safety ground system installed in the building. The idea is that this type of installation isolates the sensitive equipment from noise on the building ground safety system.

At the service entrance this isolated ground is connected (bonded) to the regular safety ground and the neutral.

This separate ground will normally have a higher impendence than the regular safety ground system, but will still provide protection. The goal of the installation is isolation from noise, not added safety, since it doesn't provide added safety.

Both the screw and the metal bracket of the outlet are isolated from safety ground in this outlet. If the cover of the outlet is removed and the hot wire has somehow come in contact with the metal bracket then touching the metal bracket will cause a shock that may cause injury or death. In many (most all?) typical home electric installations, plastic outlet boxes are used and no actual metal conduit is present so there is nowhere to connect the ungrounded portions of the outlet.

In hospitals these outlets are not allowed in patient care areas so believing the outlets somehow offer extra safety due to some imagined association with hospital installations is nonsense.

Other than the added feature of potential injury or death, these outlets provide no added features over say a hospital type outlet that will provide a more firm connection, without the added safety risk, in a typical home installation.

 

[pma]

This "study" appears to be from the year 1995. Have you verified that all of the study, except for the historical elements, still completely applies worldwide? Did you just post this item for fun or is there something to learn about the electric grid in today's world?

Changes in technology are creating changes even among the stodgy electric power companies, at least in the U.S.

Power distribution networks and schemes and protecting schemes have not changed since and the info in the document is pretty good. I have been installing complicated industrial systems in USA, EU and Japan and always had to fix the issues related to the different earthing and protecting systems used in these parts of the world.

 

[ShiZo]

In some areas of buildings where sensitive electronic equipment is installed, such as computers, it is considered an advantage to run a separate ground wire back to the service entrance instead of using the general safety ground system installed in the building. The idea is that this type of installation isolates the sensitive equipment from noise on the building ground safety system.

At the service entrance this isolated ground is connected (bonded) to the regular safety ground and the neutral.

This separate ground will normally have a higher impendence than the regular safety ground system, but will still provide protection. The goal of the installation is isolation from noise, not added safety, since it doesn't provide added safety.

Both the screw and the metal bracket of the outlet are isolated from safety ground in this outlet. If the cover of the outlet is removed and the hot wire has somehow come in contact with the metal bracket then touching the metal bracket will cause a shock that may cause injury or death. In many (most all?) typical home electric installations, plastic outlet boxes are used and no actual metal conduit is present so there is nowhere to connect the ungrounded portions of the outlet.

In hospitals these outlets are not allowed in patient care areas so believing the outlets somehow offer extra safety due to some imagined association with hospital installations is nonsense.

Other than the added feature of potential injury or death, these outlets provide no added features over say a hospital type outlet that will provide a more firm connection, without the added safety risk, in a typical home installation.

Long story short I have to replace this outlet? It's all plastic around it but it still not safe like that right?

 

[jasonhanjk]

That is news to many people who have home theater AVRs with such connections and quite audible ground loops.

The answer was in the video and in Bill's presentation. Even though you have a double insulated device, there is capacitance between the chassis and the mains wiring that causes mains leakage and current to flow to the chassis of another device similarly situated but at different ground potential.

As I explained in the video, there is no such thing as a system with no ground loop. It exists by definition in any system using unbalanced connections. You get lucky that it is not audible vast amount of time. Not because it doesn't occur due to two-wire electrical connection.

Even with this system?

 

[amirm]

Even with this system?

Of course. The problem starts before the circuit even begins. There will be capacitance between the transformer primary and secondary that you don't see on schematic but sure as heck exists. Bill shows this in one of his slides:

That earth terminal in your diagram is a fantasy:

No way that circuit ground is really at ground potential in AC.

 

[dsnyder0cnn]

Only if there is current you have reason to be concerned.

I don't have a way to measure current. I'm not sure how connecting two components that are 33 volts apart would not cause current to flow between them. I just don't have any sense of what that circuit looks like (if it's a circuit at all).

 

[Lambda]

I don't have a way to measure current.

You have a pure volt meter that can’t measure current?

I'm not sure how connecting two components that are 33 volts apart would not cause current to flow between them.

Because of high impedance.
For current to flow there must be a some sort of current path. the higher the impedance the smaller the current.
If you know voltage and current you can estimate impedance.

 

[Klint]

Hi, could someone please help a novice here.
Normally when having these problems the sales guy says connect everything to the same outlet.
Have i understood it correctly that that will not solve the problem.
If i have the problem and XLR is not a possibility, what then?

 

[Lambda]

Normally when having these problems the sales guy says connect everything to the same outlet.

"Normally" this is good enough that you normally don’t hear the problems from the ground loops.

If i have the problem and XLR is not a possibility, what then?

there is not mush a novice can do that's save and legal and reasonable and cost effective.

Maybe Isolation transformer.

but step 1 is
Educate yourself
https://web.mit.edu/jhawk/tmp/p/EST016_Ground_Loops_handout.pdf
And systematically fined the root cause of the problem

 

[solderdude]

Normally when having these problems the sales guy says connect everything to the same outlet.
Have i understood it correctly that that will not solve the problem.

This might and might not solve the problem. That depends on what is generating the ground loop currents and how they make it into the chain.

If i have the problem and XLR is not a possibility, what then?

Then you need to find out when the hum goes away.
Does it happen when only the amp is connected to nothing else ?
Does it happen when the amp is also connected to a music source that is switched off and not connected to mains ?
Does it only happen when the source is also connected to mains but switched off ?
Does it only happen when the entire chain is connected to mains and switched on.

Work your way back from the speakers and see where it starts to happen.
At that point you must find a solution at that point.

 

[Klint]

Thank to All.
I get my noise when i connect the power amp to my reciever via rca.
After some testing i have found that:

I have the receiver and the poweramp to the same outlet.
I connect the speaker cable to the receiver, doesnt even have to be connected to the amp.
Connect amp via rca.
Powerup receiver, get the noise, poweramp not even on.
When the poweramp isnt in the chain its quite.

So XLR is not an option and both are in the same outlet.

 

[Lambda]

@Klint

https://web.mit.edu/jhawk/tmp/p/EST016_Ground_Loops_handout.pdf
And systematically fined the root cause of the problem

Have you read this yet? there is an extent trouble shooting guide in it.

Powerup receiver, get the noise, poweramp not even on.

so you get noise from the receiver not the power amp?
is the receiver connected to ground? How?
is the receiver connected to something else (ground)? disconnected it.

 

[Klint]

@Klint

Have you read this yet? there is an extent trouble shooting guide in it.


so you get noise from the receiver not the power amp?
is the receiver connected to ground? How?
is the receiver connected to something else (ground)? disconnected it.

Both are connected to ground via the same outlet. No other equipment connected.
Noise appears when receiver and poweramp are connected (rca only).

Receiver is powered up with speakers connected to it, and i have no noise.
If i now connect the poweramp to the receiver with rca, nothing else changed. I get the noise.
And of course if speakers are connected to poweramp i have the same result.

Poweramp is shut off and has no speakers connected, its just in the wall outlet and connected via front left rca to receiver.

All channels are effected.

So if I understand the ground loop is RCA to RCA since both units are connected to the same outlet

 

[Lambda]

So why don’t make the effort to tell us a little more about your system?!
Your AVR is connected to PE safety ground? sure? that's unusual....
What Reciver? what power amp what else's is connected? .... and so on.


Better give too detailed information then not enough!