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Ground loops

GreeneDeux

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Jul 20, 2024
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Canada
Hi everyone,

I'm planning out my first "proper" desktop system, i.e. separate USB DAC and amp (of presumably good quality), and something I keep seeing mentioned is ground loops, or ground noise. I don't think I have any of this going on in any of my very pedestrian equipment at the moment so I'm just curious if there's any way to tell whether it will be a problem in the future? All of my desktop stuff is plugged into a single surge protector sound bar - computer monitors, the computer itself, and my old Wii U + gamepad charger, and 3DS charger - if that's of any significance. The amp would be plugged into the same, with the DAC being directly USB-powered.

Edit - I forgot to mention, I also use a power line adapter to get a wired ethernet connection to my PC from the inconveniently-placed modem. The modem side wouldn't be on the same circuit but the PC side is, albeit on a different outlet on the other side of the room and not on the power bar. I imagine that's very electrically noisy but it's not grounded so shouldn't transmit any noise onto ground, at least.
 
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Ground loops occur when signal return paths differ among components. It is almost impossible to predict in advance unless you have some engineering knowledge and working knowledge of all the components' grounding schemes. Plug it all in and see if it works OK, then worry about troubleshooting if not.

Overview of ground loops here:

Many other articles online.
 
It's not a common problem with "short" connections that don't go across the house, etc. It's also more common with low-level signals like the signal from a phono pickup because the preamp amplifies any noise along with the signal.

Pro equipment uses balanced connections to virtually eliminate ground loop problems, but most home equipment is unbalanced.
 
Ground loops occur when signal return paths differ among components. It is almost impossible to predict in advance unless you have some engineering knowledge and working knowledge of all the components' grounding schemes. Plug it all in and see if it works OK, then worry about troubleshooting if not.

Overview of ground loops here:

Many other articles online.
Most of the technical information goes over my head unfortunately, but I think I get the gist - whether a ground loop will form or not depends on the hardware, right? How it's been built and configured internally, whether it's grounded or not, etc. So I guess you have to trust it was designed by an engineer that knows what he's doing...

It's not a common problem with "short" connections that don't go across the house, etc. It's also more common with low-level signals like the signal from a phono pickup because the preamp amplifies any noise along with the signal.

Pro equipment uses balanced connections to virtually eliminate ground loop problems, but most home equipment is unbalanced.
So, I should be a bit less prone to developing a ground loop, by that metric. Alright. It's a shame balanced connections aren't the standard - if I wanted to use gear with balanced inputs and outputs, it'd be over twice my budget, otherwise I'd just do it.

I did see a recent ground loop or maybe just electrical noise-related thread by FiftyTifty who gets to hear the bits his GPU and CPU are pushing around under load, which doubled my concern... don't want that to be me!
 
I think I know what to do. I won't have the DAC for a while since I'm waiting for it to go on sale. But, I can get the amp, and get a cheap RCA to 3.5mm splitter since I want to experiment with preamp out to my mini soundbar anyways, and use it to connect the amp to the headphone jack of my current USB dongle. Then see if I get noise. Unless I'm missing something, I think that should be a good simulation. Then I'll know ahead of time whether I need a ground loop isolator, or can just use regular interconnects, so I won't have to double-dip, and won't have any money in that I wouldn't otherwise. That setup will be a Topping D10S into a Schiit Magni Heretic if you're curious btw (though you might already know that from my other thread, Doug).

P.S. - Why oh why must such short cables be so expensive???
 
If you have everything Plugged in to the same electrical circuit, I'm seriously wondering how or why you would have Any Ground Loops, as everything will have (in effect) the same 'Potential'.

As long as you don't have any Fridges or motors etc hanging off that circuit, noise shouldn't be a direct problem either but not impossible from external sources like lighting etc.
Not sure what or how a 'Ground Loop Isolator' would help anyway really, better to find and fix the issue instead of putting a Band-Aid on it,.. lol

P.S. - Why oh why must such short cables be so expensive???
I don't know,.. why should they be? .. what type / brand of short expensive cables are you purchasing ??
 
The cheapest I could find was a 0.3m pair for $12.68 CAD on AliExpress... oughta be half that in my opinion. Especially considering a 2m cable doesn't cost much more!

Short RCA pairs less than $20 CAD - that I can get with free or cheap shipping (in-store they are non-existent in my area) - seem very rare to me, or maybe I'm not looking in the right places?
 
Well gee that's not too bad,.. it's the connector prices really not the length of cable keeping the prices similar at those shorter lengths.
 
I suppose it's not that bad in the grand scheme of things, no, especially not when there's sub-foot interconnects selling for $50 or $70 or $130 USD and those are the "budget" "premium-grade" ones! With pixie dust coating the copper wiring and unicorn farts infused into the shielding, and braiding of the finest spider silk... lol. $12.68 CAD isn't entirely unreasonable but still, there's a couple different ways I could configure my system, requiring different cables and/or adapters, and I'm not 100% sure that how I initially do it will be how I keep it... it can add up quick. And, being dead honest, I don't really like ordering from Ali if I can avoid it. Cheapest I can find outside of Ali are right around $20 CAD.
 
I suppose it's not that bad in the grand scheme of things, no, especially not when there's sub-foot interconnects selling for $50 or $70 or $130 USD and those are the "budget" "premium-grade" ones! With pixie dust coating the copper wiring and unicorn farts infused into the shielding, and braiding of the finest spider silk... lol. $12.68 CAD isn't entirely unreasonable but still, there's a couple different ways I could configure my system, requiring different cables and/or adapters, and I'm not 100% sure that how I initially do it will be how I keep it... it can add up quick. And, being dead honest, I don't really like ordering from Ali if I can avoid it. Cheapest I can find outside of Ali are right around $20 CAD.
Most of the cost is in the connectors and assembly. The difference in cable cost going from 1' to 3' is probably in the mud. The other factor is volume; most consumer interconnect cables are probably 1 m and 2 m so made in huge batches. Sub-1 m cables are likely small volume thus cost relatively more to manufacture (programming, tooling, and all that jazz).

Unless you really need short cables, I'd suggest getting 1 m and/or 2 m cables and letting the extra lie loosely behind the components. Always a chance you'll move something later and discover that sweet, expensive, custom 0.25 m cable is useless. Don't ask how I know this...
 
I buy cables usually in a store that sells music equipment (instruments, studio speakers etc.) . One of the famous here where I live is Thomann. They sell cables at reasonable prices. I am sure similar shops exist in your region as well.

Here a link just as an example:
https://www.thomannmusic.com/audio_cables.html

On their webpage you can filter the connector type (for example RCA male/RCA male), length (0.3-1.5m) and even price range.

Connectors of good quality are for example Neutrik, Rean and Amphenol. I can recommend the Cordial cables, they are of very good quality and not expensive.

They have cables for balanced connections (XLR) too.
 
In unbalanced analog interconnect systems 'Ground Loops' are a fact of life!
But:
a] if the area inside the loop is small
b] the end-to-end resistance of the paths is low
Then there will be no problems.
 
I'm planning out my first "proper" desktop system, i.e. separate USB DAC and amp (of presumably good quality)
A good-quality amp and DAC will have balanced interconnects. Using decent gear with balanced analog connections will stop spreading the ground-loop efects which are very likely with PC as a digital source.
 
In unbalanced analog interconnect systems 'Ground Loops' are a fact of life!
All of my desktop stuff is plugged into a single surge protector sound bar - computer monitors, the computer itself, and my old Wii U + gamepad charger, and 3DS charger - if that's of any significance. The amp would be plugged into the same, with the DAC being directly USB-powered.
Gee Excuse me guys,.. did any of you actually Read what the OP said ??
He is creating a 'Desktop' system, with (as can be read above), Everything plugged into the Same Circuit !!,.. There is No change in Potential and obviously NO change in possible Earth Voltages.

He is Not building a Home Studio, with appreciable distances between Power Outlets or Equipment.
Sure, being able to run Balanced would provide even better performance and rejection of noise, but on a desktop, All the distances are Small, even in Audio terms.

Not saying it's impossible,.. but seriously, probably unlikely.
If you follow the setup below,.. you will be starting with at least a half decent chance of experiencing Zero issues,.. just like what I'm sitting in front of now and enjoying listening to,.. Hum ??, Ground-Loop ??,... none here Josephine,.. LOL

ground_control_05-kncQ851pmnruvSpGleqinbqWfz43yE8..jpg
ground_control_06b-UxI9u2lHrNJNAFIvnlsb14SZ46TuvVJs.jpg


;) :) :cool:

Images courtesy of SOS
 
Gee Excuse me guys,.. did any of you actually Read what the OP said ??
He is creating a 'Desktop' system, with (as can be read above), Everything plugged into the Same Circuit !!,.. There is No change in Potential and obviously NO change in possible Earth Voltages.

He is Not building a Home Studio, with appreciable distances between Power Outlets or Equipment.
Sure, being able to run Balanced would provide even better performance and rejection of noise, but on a desktop, All the distances are Small, even in Audio terms.

Not saying it's impossible,.. but seriously, probably unlikely.
If you follow the setup below,.. you will be starting with at least a half decent chance of experiencing Zero issues,.. just like what I'm sitting in front of now and enjoying listening to,.. Hum ??, Ground-Loop ??,... none here Josephine,.. LOL

View attachment 383150 View attachment 383151

;) :) :cool:

Images courtesy of SOS
There are multiple sources of ground loops in the OP's system. PC's, even if plugged into the same outlet as everything else, create multiple grounds for the different voltages. In addition the "modem" mentioned by the OP can also have different ground potential (Cable modems are notorious for this). As mentioned it is impossible to predict in advance but it is far from "unlikely". In fact I have never experienced a system using a cable modem to not have ground loop issues (usually a good quality isolator will work).
 
Oh well, it's an Impossible situation then,... lol
OP,... give up, buy a Harmonica and make your Own music,... LOL

I'll just pretend that nearly 40 years in the Live Audio world and 5 studios & myriad installations, avail me of Zero experiential knowledge,.. let alone my Own completely Silent system,...
I'll leave it with you,.. Plug stuff in anywhere and use any cables,... LOL ;)

OR,.. even better,.. Plug it all in and see what happens !! ;) before being convinced by everyone it will undoubtedly be a Disaster.
Cheers :)
 
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To give one example of how the ground potential of a device can be generated, below is a typical powerline filter that is used in devices with switch mode power supplies (SMPS). SMPS can send a lot of switching noises back into the AC supply line, and these filters are used to minimize these RFI (radio frequency interference) from getting into the AC mains to meet governmental EMI/EMC (electromagnetic interference/compatibility) requirements.

You can see that AC power ground is often used as a dumping ground for the unwanted noise. That means the ground of the device is not going to be "clean" due to the injected RFI. Therefore, the ground of the device can be at a different potential than the other devices connected to the same AC outlet.

That's why pro-audio has all switched to differential (balanced) signal connections that do not reference ground and doesn't care what its potential is.


6EQ3.jpeg
 
A really good way to eliminate risk of ground loop in a simple system - especially one that is simply PC-Dac-Amp is to use an optical TOSLINK connection from PC to DAC. This fully breaks any electrical connection between the PC and the DAC.

If you don't have toslink out from your PC, cheap USB to toslink converters are available.
 
That's why pro-audio has all switched to differential (balanced) signal connections that do not reference ground and doesn't care what its potential is.
Well, with the greatest of respect, that is NOT why Pro Audio has 'Switched' to (Balanced) Signal connections.
Studios, Live Entertainment and Pro Level Installations have been using Balanced connections for a lot longer than Switch-Mode power supplies have been in existence :)

Good reason, to Not use SMPS's,.. ;)

Still a Lot of Single-Ended stuff around in Pro, Semi Pro and Corporate / Educational facilities.
If good common sense and care is taken, it is NOT Always guaranteed to be a Problem.
Testing is Important for 'Mission Critical' applications and ideally alternate equipment utilized, if the initially specc'd stuff sucks or is crap !!

Just give me my Old fully discreet API, with it's 48volt power supply :cool:
Noise floor ??, Dynamics ?? ..... Gain ,... +28 through the EQ +40 on the Output .... :)
Digital ?, SMPS and 15 to 18 volt rails,.. hmmmm LOL
Seriously miss that console, ... sigh :(
 
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