Ground Loop Noise?

Rowan88 · 3 Apr 2019 at 15:57

Hi,

I just purchased a Scarlett Solo USB Audio Interface. I have it connected via RCA to XLR cables to my Yamaha HS5 Monitors.

When I go to plug the USB into the PC I hear a buzzing noise from the speakers when nothing is playing. Even if I touch the USB off the IO Panel I get the noise.

My old UMC22 never had this issue and the only two things that are new today is the Scarlett Solo and cables.

Is this noise caused by the USB or cables?

All help is appreciated.. I can provide video/audio if required.

Cheers

Haze · 3 Apr 2019 at 16:50

Does it still make the noise when you disconnect the USB? I presume the speakers are mains powered? Not powered by the USB?

easyrider · 3 Apr 2019 at 16:58

Try plugging the interface into a internal USB port on the case rather than the back io panel.

d_brennen · 3 Apr 2019 at 17:00

Noise could be introduced by shoddy cables or switch mode power supplies/voltage regulators. I'd replace it with something of a known quantity, Amazon basics seem ok.

I've a few Scarlets and none of them have hum from USB

Rowan88 · 3 Apr 2019 at 17:57

1. When I disconnect the USB cable the noise disappears, but that could be because its USB powered.
2. I tried a different USB cable, I tried all the ports on the back of the PC and the ports on the front of my case, all give same issue.
3. In terms of power, the interface I had before is going into the same PC, same power outlets etc and that never gave me this issue.

Going from what I changed (unit and cables) im starting to think its the RCA to XLR cables that could be causing it, but because my older unit has TRS at the back I cannot test these cables in the old unit

Guess I will need to just buy different cables and see if problem persists, if it does then I can only put it down to the Scarlett unit itself.

In terms of connections I need RCA at the back of the scarlett, but my speakers take XLR or TRS, does it matter which I use? And does it need to be balanced or non balanced?

I might even pick up at AV Link Ground Loop isolator for £5 that goes in the RCA ports to see if that fixes it..

Also I cant find the amazon basic version I need... there is a HosaTech one. The ones I bought with it were Stagg.

Rowan88 · 3 Apr 2019 at 19:18

I've ordered the HosaTech cables and AV Ground Loop Isolator.

They come tomorrow so I will post my findings....

Rowan88 · 4 Apr 2019 at 15:15

Ok here was my results:

Stagg XLR to RCA cables = static buzzing noise on idle
Hosa TRS to RCA cables = static buzzing noise on idle
Stagg XLR to RCA with Ground Loop device = static buzzing noise on idle
Hosa TRS to RCA cables with Group Loop device = NO BUZZING!

I am severly confused as to how this is being caused.

I am still convinced because my Behringer w/ TRS to TRS cables worked fine with no buzzing that if I use the Scarlett Solo because it uses RCA ports I need the ground loop isolator device?

.. but if that was the case why is it still buzzing with isolator using XLR cables...

hmmm

Rowan88 · 4 Apr 2019 at 19:39

I've decided to take a risk and buy a Scarlett 2i2 (for the TRS balanced outputs) and see if that works similar to my umc22 did..

I have arranged for the other items to be returned (the total costs work out about the same anyway)

Rowan88 · 5 Apr 2019 at 16:01

Scarlett 2i2 came and using my original TRS balanced cables there is no interferance.

So I can only assume the RCA ports on the Scarlett Solo because unbalanced was causing the issue, and rather than buying isolators and different cables probably best spend the extra £10 and get the 2i2.

Hope this helps others...

easyrider · 5 Apr 2019 at 18:50

Rowan88 said:
Scarlett 2i2 came and using my original TRS balanced cables there is no interferance.

So I can only assume the RCA ports on the Scarlett Solo because unbalanced was causing the issue, and rather than buying isolators and different cables probably best spend the extra £10 and get the 2i2.

Hope this helps others...

Glad you got it sorted.