Ground loop issues from computer audio

[solderdude]

Hello, I am looking for advice on how to solve ground loop issues on my home computer setup. The main thing is that I want to be able to quickly switch between a desktop computer and a laptop for the audio source. Here is a schematic of the setup :

View attachment 160689
I am considering replacing the power strip with a filtered one such as https://www.av-connection.com/?PGr=13568 .
Would that be a solution?
I thought plugging all components in the same power strip would solve ground loop issues, but I still have the ground loop.
Thanks for any insight.

Seeing you are using onboard audio and RCA audio to speakers = asking for ground loops.

Solution could be:
1: external DAC connected via optical or via USB through an USB electrical isolator.
2: Use audio line transformers in the RCA audio path and use the balanced input (when available) via those audio transformers.

Both options already have been recommended already.
I would be careful with that particular ifi product

 

[JayGilb]

How would you solve interference then ? what's the difference with the ground loop ? I thought ground loop was causing interference

A ground loop can cause mains frequency and harmonics hum as well as buzzing from mouse movement and gpu activity.
The ground loop changes the ground reference voltage and any signals that now fall between 0 volts and the new reference voltage will possibly be amplified by the powered speakers.

 

[ppataki]

430 euros and this massive thing turning my living room into an industrial zone. Suddenly XLR cables don't sound so bad

Does not look that bad:

IKEA rulez!!

 

[Bouly]

Thanks all for the insights. I still have not received the 2 products I ordered that I mentioned before, but in the meantime I decided to stop using bandaids and try something thats going to fix the problem without making the setup too complicated. I have decided to switch to XLR because my speakers (Eris E8) support it. I knew I had to order a really good DAC, because from Windows + Foobar with ASIO + Asus Sonar Essence STX + Eris E8 that is probably the best bang for buck for a really good sound quality with a reasonable budget. And I have already tried external DACs in the 200 - 300 euros range (schiit audio and sony PHA-1EU if I remember correctly) and even though these fixed the ground loop issues they did not match the sound quality of the Asus Sonar Essence STX with the Muses Op Amps, and so after these I switched back to my trusty internal sound card. Also I did not want to order a chinese DAC because at this price point maybe I can support a production that is more local. So in the end I splurged on an RME ADI-2 -DAC FS. I actually have received it today before the other products I ordered earlier, because its coming from a lot closer. I thought it would be overkill for the Eris E8 speakers but I'm actually hearing a difference with the Asus sound card. The RME ADI-2 is just as clear as the Asus sound card, but it is more detailed and the sound is definitely more "3D". I listened to Nightwish's "walking in the air" and I can hear every small detail of the song, I can definitely hear things that I did not notice earlier. In a way what is amazing is that even lower quality sources like a 480p youtube music video sound better.

I have two questions related to using external DACs on windows / mac. Not sure if I should open a new thread for these :
- on Windows, I'm using the motherboards optical SPDIF output to the DAC. It is working and the sound is ok, but the thing that I'm not sure about is that I can change the sound volume from windows. I think the sound should not be altered by the low quality windows / motherboard parts. Which media player do you recommend for windows for playback ? or maybe I should connect it through USB for the best quality
- on Mac on the other hand I connected through USB, and I can't change the volume from OSX interface, which seems logical, but it is extremely loud by default.

 

[Bouly]

It seems that using SPDIF input on the Adi Dac, some processing is done on the computer motherboard which is not ideal. Thankfully my keyboard, which is plugged into the USB switch, has itself 2 USB ports on it, one of which is used by the mouse, and the other free. So I plugged the DAC into the second USB port of the keyboard. In this way when I toggle the USB switch, I can toggle between the two computers for keyboard, mouse, and DAC usage. I also installed the windows drivers for the DAC. Before, it seemed something was off with quality of the Dac sound output, but now after installing the drivers, I have the option in Foobar to use Madiface Asio, and the sound is as expected from a Dac of this caliber.

 

[Lambda]

Lots of unnecessary expensive and ineffective suggestions.
3.5mm to RCA from a PC is asking for problems and is bad practice

Get a DAC with multiple inputs USB, SPDIF, Toslink
and use it as switcher between mac and PC.
or get tow USB sound cards like the 10€ apple dongel and an 7€ USB isolators.

 

[Bouly]

Get a DAC with multiple inputs USB, SPDIF, Toslink

Yes in the end I got an RME ADI-2 DAC. It solves the ground loop issue and the sound quality is better than before. However it is taking me time to get used to the new sound and I got some listening fatigue troubles

 

[Lambda]

Yes in the end I got an RME ADI-2 DAC

That's quite an impressive upgrade.

 

[Lttlwing16]

I'm picking up PC noise through the SE input on my THX 789 Headphone amp. I was gifted a gaming PC and since introducing it has been a PITA for noise. This is heterogenous electrical noise which changes depending on what's going on in the PC, i.e. moving the mouse etc. similar to the OP's.

Is this a grounding issue with the PC or 789 or both? FWIW I have a DROP GRACE SDAC balanced output going into the XLR input of the 789. This input does not have the same noise. The SE input of the 789 is connected to my Technics Sl-23 turntable RCA output.

If I power off the troublesome PC the noise goes away. The 789 is not directly connected to the PC accept for being plugged in the same power outlet (two different and separate power strips exhibited the same issue), and both are connected to the same mixer which outputs to my powered Mackie monitors. The 789 is connected to the mixer via RCA, and the PC is connected via Toslink>cheap DAC>RCA to the mixer.

Thanks in advance,

David

 

[Berwhale]

I think it's possible that the XLR cable or plugs are wired incorrectly and that the USB signal ground from your PC is traveling down the balanced cable sheilding to the 789 and out through the RCA ground to your turntable (AKA 'XLR Pin 1 problem).

 

[Lttlwing16]

I think it's possible that the XLR cable or plugs are wired incorrectly and that the USB signal ground from your PC is traveling down the balanced cable sheilding to the 789 and out through the RCA ground to your turntable (AKA 'XLR Pin 1 problem).

Thanks for the reply and input. The culprit PC is not connected to the SDAC or 789 by USB. Would this matter?

The culprit PC is connected to the SDAC via Coaxial output from the onboard soundcard.

I plan on unplugging everything this evening and trying to systematically rule out different components. I also have a different PSU I may try if all that fails.

 

[Lambda]

Lttlwing16​

what is conected to the "DROP GRACE SDAC"
Pleases provide some sort of diagram with devices and cables.

 

[Berwhale]

AFAIK, coax can provide a path for a ground loop just as well as USB. Can you switch the PC/SDAC link to Optical (Toslink), that would break any electrical connection between the PC, SDAC and the rest of your equipment.

Also, a ground loop is formed by multiple components in your setup. I don't think it's helpful to try to find the one 'culprit' in the chain.

A diagram of your complete setup would be helpful.

 

[monkeyboy]

Isn't a "ground loop" caused by using separate ground connections with your device chain...it looks like everybody has the same ground connection via the power strip...wouldn't this just be noise in the system due to another cause?

 

[anotherhobby]

USB sometimes carries CPU noise and noise from other USB devices down its power wires. I have this issue as well, and I can hear the mouse movement in my tweeters as well as other processing tasks if I don't hook stuff up to avoid it. You need to isolate the USB power from the audio equipment so there is no physical path. Using a Topping D10s and converting to optical works flawlessly to solve this. That's what I'm doing now.

The iFi iDefender is supposed to also fix this by dropping the USB power, and then if you need USB power past it you need to plug USB power into the adapter from an external source. I have one on order, but it's only $40 less than the Topping D10s and less functional for other things, so I'm not sure if it's even worth it. I can't report if it works until I get it (it's about 2 weeks out right now). I imagine you could probably even dissect a USB cable, cut the power wires, and then inject externally and probably accomplish the same thing, but I have no idea and haven't tested this theory.

 

[anotherhobby]

The iFi iDefender is supposed to also fix this by dropping the USB power, and then if you need USB power past it you need to plug USB power into the adapter from an external source. I have one on order, but it's only $40 less than the Topping D10s and less functional for other things, so I'm not sure if it's even worth it. I can't report if it works until I get it (it's about 2 weeks out right now). I imagine you could probably even dissect a USB cable, cut the power wires, and then inject externally and probably accomplish the same thing, but I have no idea and haven't tested this theory.

Go figure, Amazon was confused on my shipping and the iFi iDefender just now showed up! I just plugged it in and it totally didn't do squat. It didn't even reduce the noise. The only method I can offer that I know works is what's mentioned above... to use a D10s to convert USB to optical. A cheaper alternative is this Douk Audio USB>TOSLINK adapter, but I've had two now that got touchy, and if you bumped the USB cable they'd cut out for a moment. That's what drove me to the D10s, so I can't say that's a great option, but it is cheaper and much smaller.

 

[antcollinet]

Isn't a "ground loop" caused by using separate ground connections with your device chain...it looks like everybody has the same ground connection via the power strip...wouldn't this just be noise in the system due to another cause?

No, a ground loop can be formed by any loop of low impedance. Eg strip earth to PC to Coax to dac to headphone amp, to turntable to TT earth back to strip.

Difficult to tell what the likely scenario is without the requested component/interconnect/mains wiring diagram.

However the suggestion of using optical from the PC rather than Coax is the solution most likely to solve the issue based on what we know so far.

 

[Lambda]

However the suggestion of using optical from the PC rather than Coax is the solution most likely to solve the issue based on what we know so far.

PC is connected via Toslink>cheap DAC>RCA to the mixer.

So it is not clear or how and to what the pc is connected!

The culprit PC is connected to the SDAC via Coaxial output from the onboard soundcard.

So it is? and why did yo usay via toslink?

Check if grounds are connected via the spdif cable.
Check if noise goes away if you unplug the coax.

plese provide a full system drawing/diagram with all connections

 

[Lttlwing16]

Thanks @Berwhale and @Lambda and everyone else. And sorry for not providing diagrams. My setup is pretty complex, and I wanted to trouble shoot before I drew it up.

That said, I was able to isolate the issue and reproduce. The THX 789 has a SE pass-through and I had this connected to an RCA input of my Yamaha MW12 mixing board so I can listen to my turntable through my Mackie powered speakers. This mixing board, PC, and 789 all shared the same power outlet/circuit. *Once I unplugged the 789 SE passthrough RCA cable from the MW12 board, the PC noise disappeared from the balanced headphone output of the 789.

Technics SL-23 RCA OUT>THX 789 SE INPUT>SE PASSTHROUGH>MW12 RCA INPUT
>Balanced XLR output>Dan Clark Aeon RT


Now what is interesting, when I was troubleshooting this, I had completely detached the PC from all connections except Keyboard/Mouse/Monitor and power cable. It had no connection to the headphone amp or MW12 mixer apart from using the same power outlet. Yet, the PC noise continued in the headphones. (The noise is actually coming from the PCIe GPU, as I can hear it if I put my ear close to the GPU while it's on, but that's a separate issue.) I reconnected everything that was previously connected to the PC, including the Toslink>RCA converter (not the SDAC)>MW12, while leaving the SE pass through unplugged from the MW12, and the noise continued to be eliminated.

The Yamaha MW12 does not have a three prong power supply. It has a large brick and a two prong power cable off the brick. The 789 also has a two prong wall wart.

Question is how would I go about fixing this issue? (apart from unplugging the SE passthrough )

 

[Lttlwing16]

So it is not clear or how and to what the pc is connected!


So it is? and why did yo usay via toslink?

Check if grounds are connected via the spdif cable.
Check if noise goes away if you unplug the coax.

plese provide a full system drawing/diagram with all connections

Sorry man, I actually have both.

Toslink>Cheap DAC>RCA input on the MW12
COAX>SDAC>XLR OUT>HEADPHONE AMP

I use the Toslink connection for gaming and videos from the mackie's, and the coax for the headphones. The SDAC is actually USB powered from a SECOND adjacent PC tower, that remains off most of the time, unless I want to listen to headphones via the SDAC or rip vinyl. I know confusing and complex!