Electrical interference noise coming from studio monitor speakers

[dtb1]

Hi all, hope this is the right section to ask about this.

This week I purchased two KRK Rokit RP5 G3 monitor speakers, however they are both emitting a noise that sounds like static/electrical interference or something. It's a fairly quiet noise, but loud enough to be distracting. It's incredibly frustrating for the ear as I need to mix/master an important music project.

Each monitor speaker is connected to a Focusrite Scarlett 2i4 audio interface (USB powered), both using a XLR Male to Quarter Inch TRS Balanced Jack. The only other things connected to the PC (Win7 64-bit) are a keyboard/mouse, Alesis QX61 midi controller keyboard, monitor, and ethernet cable. I have tried disconnecting these one by one, and all at the same time, but the interference noise is still present in both speakers.

My computer and electrical knowledge isn't great, but I've reading around and apparently it could be a ground loop problem. However, I have no idea how to rectify this. I don't think there is a problem with the speakers because if I remove the XLR/TRS cable from the speaker, with the power cable still connected, the noise disappears completely.

Strangely, the static noise seems to increase when I move the mouse. I have tried 4 different mouses; the very cheap mice seem to create a much less noticeable sound, but it's still present. My default mouse (Gigabyte M6900) creates a much more noticeable sound when I move the cursor around.

Also, the noise disappears when something is loading - for example, I was just updating my graphic card drivers, and while the files were extracting the noise disappeared! This also happened today when installing an 8gig patch for a game - during the installation process the noise disappeared completely, and was heavenly for the ears. This is how it should be sounding at all times. Once the game had finished patching though, the noise resumed.

As I say, I have very little knowledge in electronics and don't know what else to do. I feel like I've tried most things but nothing seems to have worked. I have a feeling the speakers are picking up an electrical signal from CPU processing, due to the fact that the noise reacts to mouse movements and software loading.

This is driving me insane! Is anyone able to shed some light on this?

Thanks for reading 🙂

 

[WyomingKnott]

As a start, can you connect them to another input? Even the line out of an iPod using the unbalanced input? Or, even better, if you have another balanced audio source you could test with. The idea is to isolate the components one at a time.
To my mind the issue has to be in or after the Focusrite Scarlett 2i4, since you don't really get noise into the USB data stream. It could be that your USB link has issues, but that's fairly unlikely. So the idea is to test one component at a time.

While I strongly believe in isolating one component at a time (got any other speakers you could test and see if the noise comes), my best guess is that you are getting some sort of RF interference from the PC. How close to the PC is the Scarlett? You said it's USB powered; does it have another power input so you could try giving it cleaner power?

 

[Traciatim]

I had a similar problem with my on board audio picking up electrical interference during video usage, I could actually hear a slight buzzing that was the same frequency as my frame rate. It would go from a click or tick during slow frame rates all the way up to an annoying buzz during normal play and a higher pitched screeching on loading screens.

I'm not very familiar with the Focusrite Scarlett 2i4 you mentioned, but does it just get power through the USB and the audio is supplied through anotherconnector or is all the audio also sent down the USB port? Does it work like a software sound card that sends the audio digitally to the device?

If it's just the power you could try plugging it in by itself to a powered USB hub or other USB power source. You could also try moving it in to different ports in your PC to ensure it's on it's own root hub that isn't shared with other devices.

 

[WyomingKnott]

A thought - how close it the Scarlett to your PC? Can you move it further? There shouldn't be any analog signals upstream of that device to get an RF buzz.

 

[dtb1]

Thank you very much for the response guys, much appreciated!

@WyomingKnott
I followed your advice and connected the speakers to another source. I dug out my old audio interface - a Line6 TonePort KB37 - and swapped it out with the Scarlett. The interference noise has completely gone! You were right, the problem seems to lie within the Scarlett interface. Unbelievable. I have no idea why the Scarlett interface could be creating such an interference.
The Scarlett sits on the desk, almost directly above the computer. I shall try moving it further away tomorrow, see if that makes any difference.

@Traciatim
The Scarlett 2i4 is entirely USB powered with no other connections, so all audio is sent through the USB. No option for an AC adapter either. I had a go at using different USB ports but the noise was still present. Perhaps I should try getting hold of a powered USB hub as you suggest.

Interestingly though the Line6 KB37 is also entirely USB powered too, yet doesn't create any interference noise through the speakers. This is great news, although the latency isn't so great with the KB37. It's fine as a temporary solution, but would really like to solve the issue with the Scarlett, as it was rather expensive and probably unreturnable! 🙁

Tomorrow I shall try repositioning the Scarlett as far from the computer as possible, and I'll also be able to try out the Scarlett + the monitor speakers on a friend's laptop. If an interference noise is still produced then either the Scarlet is faulty, or it just conflicts with the speakers somehow.

Thanks again, I shall report back with my findings tomorrow

 

[WyomingKnott]

I use one of these - rechargeable battery powered, but not quite the same thing:
http://www.raysamuelsaudio.com/products/predator

 

[JohnnyAshtray]

The Line 6 took away your noise because it's ad/da converters are very low quality and don't require alot of power, same with it's preamps. The focusrite has better quality converters at a higher decibel range so You should be sending your audio through that like you want to do. I actually have the same problem you are at the moment and I'm searching for help too. It's happening on my studio computer and I have actually went so far as getting a new computer 3 different times (one of which was a mac) and changing out my powered speakers and interface. I feel like I have eliminated every single source and have still had the problem each time. The only time I didn't have it is when I connected to a laptop. So all in all...it might be the damn house.