Understanding Grounding in Audio (Video)

[Deleted member 22141]

What a timely explanation.

I have been experiencing a weird phenomenon, my desktop setup I have a Behringer A800 connected to a Fiio K5 Pro, connected via USB to my PC.

Everything sounds fine. Until I switched over to a game, when the GPUs kick in (or possibly the fans on the GPUs) then there is an immediate ground loop buzzing, like a swarm of bees.

Close the game, or even switch away from it and the buzz disappears. Also turn off the monitor - even with the game running and the buzz disappears, but I think that's because the graphics card knows there is no monitor attached at that point.

Unplug the amp and the buzzing goes away. The buzzing is there in both the headphone and RCA output.

So I figured I would try the Behringer MICROHD Hum Destroyer HD400 as it only cost £20. And the buzzing is gone. It's like magic. I have switched it back and forth a few times and it's completely repeatable.

Any explanation of how that box works would be much appreciated.

 

[Lambda]

Any explanation of how that box works would be much appreciated.

It has a transformer inside braking the ground loop from PC to AMP

Are you using XLR in for the amp?
have you tried a powered USB hub?

 

[Thomas savage]

Technical explanation of different grounds in your audio system and all the misconceptions around ground loops, buzz and hum.

Bill Whitlock Presentation: https://bennettprescott.com/downloads...
Entreg Olympus Minimus grounding box review: https://www.audiosciencereview.com/fo...

Amirm opens ' can of worms ' and spills contents on Internet... ..

 

[Deleted member 22141]

It has a transformer inside braking the ground loop from PC to AMP

Are you using XLR in for the amp?
have you tried a powered USB hub?

No unfortunately the Fiio doesn't have XLR. I am planning to upgrade to the RME ADI-2 at some point and will use XLR at that point.

No, didn't try a USB hub, as this seems to have worked I might not get around to it for a while.

 

[Propheticus]

No doubt this means you will investigate the subject and report back. Thanks.

What's with the hostility? I was just suggesting a related topic that might be fun to debunk and would fit in the same series of videos.
There's laymen's advice given now and then that plugs need to be connected the 'right' way round. I very much doubted it would be problematic or else the plugs would have been made so that they can only be inserted one (proper) way.
Of course I could try to experiment, but I do not have measuring equipment worth tens of thousands.
In my setup I do not hear a difference, but what's that conclusion worth to you or any hard-fought audiophile with an arsenal of pseudo-science and snake-oil 'knowledge'?

 

[Lambda]

No unfortunately the Fiio doesn't have XLR. I am planning to upgrade to the RME ADI-2 at some point and will use XLR at that point.

This is a better way to do it:

No, didn't try a USB hub, as this seems to have worked I might not get around to it for a while.

Looks like your GPU is putting noise in your USB ports (in common mode) by going trough a hub you increase the common mode impedance a bit and loos a lot of the noise.
Also a view ferrits might help but mainly for the HF content.
A true Isolator wound be better.

But for real isolation maybe use the optical input!

 

[Music1969]

Technical explanation of different grounds in your audio system and all the misconceptions around ground loops, buzz and hum.

Bill Whitlock Presentation: https://bennettprescott.com/downloads...
Entreg Olympus Minimus grounding box review: https://www.audiosciencereview.com/fo...

New favourite quote for a T-Shirt or hat:

"If you did it, then go undo it!"

 

[Chris M]

In Europe in the German-speaking area, too, people have thought about it.
http://www.2pi-online.de/Was_ist_Masse_1.pdf or
https://www.google.com/url?sa=t&sou...WMAZ6BAgEEAI&usg=AOvVaw2BvoV182lyKcmgaZZ26bkI

 

[dsnyder0cnn]

For my own education, I went through this simple exercise. I removed all of the interconnects from my components so that the only cable going to each was power. I then switched them all on and used a voltmeter to measure potential difference of signal return between my preamp and each source component and amplifier by touching the outside ring of RCA collars.

What I found was that there was as much as 33 volts of difference between some components and my preamp. When I add the interconnects back, I assume that there's a significant amount of leakage current flowing among components. Perhaps this is why I usually get a slight shock when I touch my preamp to manually adjust volume. Often, this is enough to engage the preamp's protection circuitry, shutting everything down and requiring a power-cycle to recover.

Switching to sources and amps that all use balanced connections seems to work best, but that voltage difference seems pretty high. It's a bit concerning.

 

[Helicopter]

For my own education, I went through this simple exercise. I removed all of the interconnects from my components so that the only cable going to each was power. I then switched them all on and used a voltmeter to measure potential difference of signal return between my preamp and each source component and amplifier by touching the outside ring of RCA collars.

What I found was that there was as much as 33 volts of difference between some components and my preamp. When I add the interconnects back, I assume that there's a significant amount of leakage current flowing among components. Perhaps this is why I usually get a slight shock when I touch my preamp to manually adjust volume. Often, this is enough to engage the preamp's protection circuitry, shutting everything down and requiring a power-cycle to recover.

Switching to sources and amps that all use balanced connections seems to work best, but that voltage difference seems pretty high. It's a bit concerning.

...seems like you might want to do some eliminative exercises to determine which device(s) specifically are at more than 5V or so here, and then go about fixing or removing them.

 

[wwenze]

For my own education, I went through this simple exercise. I removed all of the interconnects from my components so that the only cable going to each was power. I then switched them all on and used a voltmeter to measure potential difference of signal return between my preamp and each source component and amplifier by touching the outside ring of RCA collars.

What I found was that there was as much as 33 volts of difference between some components and my preamp. When I add the interconnects back, I assume that there's a significant amount of leakage current flowing among components. Perhaps this is why I usually get a slight shock when I touch my preamp to manually adjust volume. Often, this is enough to engage the preamp's protection circuitry, shutting everything down and requiring a power-cycle to recover.

Switching to sources and amps that all use balanced connections seems to work best, but that voltage difference seems pretty high. It's a bit concerning.

If you measure the outside ring vs your body you can usually measure up to half AC voltage.

And this value differs with equipment. So it can be inferred that there will also be a voltage difference when measuring between two disconnected equipment.

Makes for a good party trick.

 

[Lambda]

In Europe in the German-speaking area, too, people have thought about it.
http://www.2pi-online.de/Was_ist_Masse_1.pdf or
https://www.google.com/url?sa=t&sou...WMAZ6BAgEEAI&usg=AOvVaw2BvoV182lyKcmgaZZ26bkI

Wow this is a Bachelorthesis...

The power cables laid in the house can be used as conductors like a large antenna. Electromagnetic waves, as they are received by radio stations, cell phones or cell phone masts, can be "received" and modulated onto the pure sine wave of the power grid. High-frequency components in the current will become the cause of a “garish, restless sound”

Some electrical devices, such as common household devices such as vacuum cleaners or hairdryers, can emit a direct current component into the network. Direct current components can, for example, rapidly reduce the efficiency of loudspeakers, since the membrane is continuously deflected by a uniform current component and the operating point of the chassis is therefore closer to the non-linear range from the outset.

i mean yes but normally i don't connect my speaker to mains

What I found was that there was as much as 33 volts of difference between some components and my preamp.

No need to be concerned by voltage alone.

When I add the interconnects back, I assume that there's a significant amount of leakage current flowing among components.

You can't assume you need to measure this!
Only if there is current you have reason to be concerned.

 

[Somafunk]

I have a leftfield question?, which could be considered in top running for the “stupid question of the year award“ but I’ll ask it anyway despite having a bsc in electronic/mechanical engineering (I should know better, yet I spent £30 on a usb cable?).

Can a dog hear the electrical noise, are they sensitive to electrical currents that we can’t perceive?.

I ask as my dog (sadly passed 2019) used to take a very circuitous route through a local hydro power station whilst running with me on my bike, it was a good shortcut to excellent mtb singletrack that ran alongside the river to the dam further up the valley and there was one specific section of open scrub/grassland between the mass of transformers and the hydro generator building that he wouldn’t directly cross, he ran round the edge, always sticking to the same route which was far longer, I always just thought it was one of his weird ways but perhaps he could sense something i couldn’t?.

Link to the wiki page for the 1930’s modernist architecture that is the Galloway hydro scheme

 

[wwenze]

I'm going to guess coil whine probably.

When I was a kid I thought I could sense the CRT TV was on while I was still outside of the house.

 

[das]

If I may ask a silly question... Almost all stereo components come with a grounding post on the rear. When should these be used? If one has say 3-4 separate components (say at least 3) before the main amplifier and if balanced connectors are used wherever possible - do you then ignore these posts? And if one uses unbalanced connectors sometimes, then what? And if one should use the grounding post under (what?) conditions - where does one connect the "other" end to?
Thank you.

 

[PeteL]

If I may ask a silly question... Almost all stereo components come with a grounding post on the rear. When should these be used? If one has say 3-4 separate components (say at least 3) before the main amplifier and if balanced connectors are used wherever possible - do you then ignore these posts? And if one uses unbalanced connectors sometimes, then what? And if one should use the grounding post under (what?) conditions - where does one connect the "other" end to?
Thank you.

I’m surprised by this, typically it’s for the ground from a turntable cartridge.”almost all component”?? Perrsonally I just see those on phono preamps, or any integrated equipment that include one. What equipment are you reffering to?

 

[AndreaT]

Watched most of it.

Another great Video.

Grounding wire for electrical equipment decreases dramatically the intensity of the current that goes through your body if you happen to touch a hot case and complete the circuit with your other hand touching a conductive surface or your bare feet on a conductive ground.

Operating Rooms have gone through various iterations to decrease the electrocution risk with macro-shock (grounding the equipment) and micro-shocks, as patients connected to an IV filled with saline or EKG wires connected to the skin across the heart are potentially harmed even by tiny currents not completely bypassed through the ground wire. The highest electrical safety is to be found in the Operating Rooms built in the 1970's with huge Isolation Transformer and Line Isolation Monitors audible alarm calibrated in mA for currents that represented a "deviation from the ideal" isolation of a transformer/balanced AC current and the theoretical maximum current that could be passed in the most unfortunate condition to a susceptible patient. At first the alarm was triggered at 3 mA, but as electrical equipment in the OR multiplied by a factor of ten (OR tables, Monitors, warmers, pumps, scopes, electrical cauteries), the limit was raised to 5mA as too often with multiple boxes and wires the audible alarm was triggered when it was very very unlikely that each one of the boxes would be in electrical contact with the lines and wires of the patient. A double fault is also required to be electrocuted when all the AC in the OR is balanced as it comes through an isolation transformer.

Another potential risk with the grounding wire is that when it breaks, the OR electrical equipment works without any noticeable malfunction (unless it has a circuit to detect the ungrounding, and most equipment in the OR did not have such a detection well into the 2000's). It was therefore not a "fail-safe" system to prevent macro and micro shocks.

 

[das]

Well, I haven't purchased my system yet - and I am afraid now I have to modify my question. I can't recall on what products I saw them when searching the internet - but when I just went to look at some I am considering - you are right - not on preamps and amps or DACs. So, humble apologies - I have seen them on some products - I just can't recall now.

 

[skyfly]

Does same amount of current on the "negative" wire of unbalanced cable result in same amount of noise?

Or is it dependent on the circuit of the gear, e.g. small size of the circuit and low impedance of ground plane within the circuit results in lower or zero ground loop induced noise?

Drawing for my question(Sorry for using DC model):

 

[jasonhanjk]

What a timely explanation.

I have been experiencing a weird phenomenon, my desktop setup I have a Behringer A800 connected to a Fiio K5 Pro, connected via USB to my PC.

The USB connection is grounded and the class-d amp is also grounded.
Typical ground loop issue. Try another amp without ground.