[LKuhlmey]

Hello everyone, I am looking for advice to help me with my (suspected) ground loop issue. I am currently in the middle of upgrading my audio setup. I recently bought a Topping A90 headphone amp as well as the Hifiman Sundara with a balanced cable. I use my Focusrite Scarlett Solo 3rd Gen as a DAC, as it will be at least one more month until I can get the Topping D90. The current setup is:

PC -> USB cable -> Scarlett Solo -> 1/4" TS to RCA cable -> Topping A90 -> 4-pin XLR cable -> Hifiman Sundara

I think the issue is a ground loop because the noise is gone whenever I unplug the 1/4" TS to RCA cable on either side.
My questions are:

1. Is the issue actually a ground loop? If not, what else could it be?

2. What would be the best (preferably cheap) way to get rid of the noise?
I was thinking of getting a ground loop isolator for the RCA connection, but I read that it will also impact audio quality. The other option would be 1/4" TS to XLR cables but I am unsure if these will help against a ground loop.

I could also just revert to my old setup for a month, but I'd hate to just have my Sundaras lying around collecting dust.

Looking forward to your answers!

 

[msing539]

Hey--are the Scarlett and Topping on the same mains outlet?

Does the noise persist when unplugging the usb from the PC?

Have you tried different USB ports?

Are you able to temporarily bypass the Scarlett with a 3.5mm to dual RCA out from PC audio jack direct to the Topping?

And what exactly does the noise sound like? A hum? Whine? Something else?

 

[LKuhlmey]

Hey--are the Scarlett and Topping on the same mains outlet?

Hi, the Scarlett gets its power via the same USB cable used for connecting it to the PC, the Topping is connected to the same power strip as the PC. I tried all USB ports I had available. I tried the Topping on a different outlet, the issue still persists, I do believe the other outlet is still part of the same circuit. I don't have any extension cables to try it on another circuit.

Does the noise persist when unplugging the usb from the PC?

The Scarlett needs to be plugged into a PC, a mains power adapter will not work. But I tried it and the noise is gone, I think that pretty much means is has to be a ground loop right?

Have you tried different USB ports?

Yes.

Are you able to temporarily bypass the Scarlett with a 3.5mm to dual RCA out from PC audio jack direct to the Topping?

Unfortunately I don't have the proper cable for that.

And what exactly does the noise sound like? A hum? Whine? Something else?

It's a humming/crackling sound that gets louder when I turn up the Volume/increase the gain on the Topping. There's also a high pitched whine whenever I move my mouse around, I just noticed.

 

[msing539]

It 'might' be the Scarlett grounding itself back through the computer. If you leave music playing and unplug the monitor from the PC side, mouse, keyboard, and other peripherals... any change?

 

[LKuhlmey]

It 'might' be the Scarlett grounding itself back through the computer. If you leave music playing and unplug the monitor from the PC side, mouse, keyboard, and other peripherals... any change?

I tested it with my old headphones in the single ended output on the Topping as well as with the Sundaras in the balanced output. The noise is still there on both, no matter how much I unplug from the PC. The high-pitched whine when moving the mouse is gone of course, but the hum persists.

 

[msing539]

My guess is the Topping is grounding through the mains outlet and the Scarlet is grounding through the PC. If you run the headphones out of the Scarlet without the Topping in the chain, no noise?

 

[LKuhlmey]

My guess is the Topping is grounding through the mains outlet and the Scarlet is grounding through the PC. If you run the headphones out of the Scarlet without the Topping in the chain, no noise?

Yep, that's how I used my old headphones before I got the Topping. There's no noise.

 

[msing539]

You can try different USB cables. I don't think they'll make a difference but you never know until you try. Once you get your DAC, hopefully this won't be an issue.

 

[msing539]

3.5mm to dual RCA direct to the Topping is another solution. Just remove the Scarlett.

 

[LKuhlmey]

You can try different USB cables. I don't think they'll make a difference but you never know until you try. Once you get your DAC, hopefully this won't be an issue.

The noise remains regardless of which cable I use.

3.5mm to dual RCA direct to the Topping is another solution. Just remove the Scarlett.

I'm going to ask a few friends if they might have one, otherwise I'll buy one on Monday. I will share results here once I get the cable, but if it's a ground loop wouldn't the issue still be there? I'm pretty sure the 3.5mm outputs on PCs are grounded via the mainboard, which is grounded via the PSU. So the loop would still be there no? I'm going to try it regardless and post the results here.

But anyway thanks for your help so far!

 

[msing539]

The noise remains regardless of which cable I use.

I'm going to ask a few friends if they might have one, otherwise I'll buy one on Monday. I will share results here once I get the cable, but if it's a ground loop wouldn't the issue still be there? I'm pretty sure the 3.5mm outputs on PCs are grounded via the mainboard, which is grounded via the PSU. So the loop would still be there no? I'm going to try it regardless and post the results here.

But anyway thanks for your help so far!

Sure thing! I had a usb ground loop at one point and it wasn't there through 3.5. I'm on a laptop though and mileage may vary.

 

[LKuhlmey]

Ok, so I got the cable and tested it via both the 3.5mm jack on the PCs front I/O as well as the Line Out on the mainboard. The noise is still there. I also measured ground continuity and it is indeed the same ground, I have no idea if that's the case with laptops though.

I'm just going to use the Sundaras directly through the Scarlett with the unbalanced cable it came with. It's way too short and it coils up which is extremely annoying, but it will be alright for a month.

Again, thanks a lot for your help!

 

[msing539]

Ok, so I got the cable and tested it via both the 3.5mm jack on the PCs front I/O as well as the Line Out on the mainboard. The noise is still there. I also measured ground continuity and it is indeed the same ground, I have no idea if that's the case with laptops though.

I'm just going to use the Sundaras directly through the Scarlett with the unbalanced cable it came with. It's way too short and it coils up which is extremely annoying, but it will be alright for a month.

Again, thanks a lot for your help!

Sure thing! Maybe someone will come up with another potential solution for you in the meantime.