Mysterious noise issue

petervatler

New member
Hi guys,

I've been struggling with this noise issue for a while, after trying many things I have no further ideas to solve this. I have a constant noise issue with my setup, it's not hum it's a kind of electrical interference. I can hear my mouse moving in my speakers or any CPU or HDD work.

My setup:
BC Rich Warlock 5 string active bass, which is connected by an unbalanced grounded cable to an IMG Stageline DI Box which outputs to a balanced XLR cable and the Focusrite Saffire Pro 14 (connected by a 6 pin FW cable to a Ti chipset FW card) interface's monitor channels output through an 1/4" TRS to RCA adapter+RCA cable to my Logitech z323 active speaker's RCA in.

What I've tried:
- connecting the display and the active speaker to other power socket
- separate the speaker cables from the PC usb cables
- disabling onboard audio
- using headphones, Bluetooth speaker instead of the active speakers
- skipping DI Box from the chain
- changing my guitar cable and instrument too

And the noise is still there, it's very annoying. The most weird thing is it was the same with my previous USB interface with different motherboard and different cables and instruments. The noise is still audiable if I don't connect any input and turn all the gain knobs down or mute or disable my audio devices, it's just there. If I don't connect my interface with all the other stuffs and just connect a simple TRS to my on-board Line In I hear the same noise. If I use my interface without my PC, powered by an adapter or I don't connect any output to my speakers the noise disappears. :facepalm:

How could I solve this issue?
 
Hi there,
Welcome to HR! :)

Sounds like a nice messy one. :p

You've done a lot of troubleshooting, which is great...In fact you've done pretty much everything I would have suggested!

Reading through, you've ruled out everything external and the motherboard, I think...
Was that just a motherboard switch or a whole different computer?

If it was a motherboard switch I'm leaning towards suspecting your PC power supply.

Do you have a totally separate computer or laptop you can test with?
 
See if the noise persists when running the laptop on its batteries.

I don't know why some desktops and laptops are noisy like this, and why others aren't.

My first audio computer (which was round the turn of the century) was dead quiet, and the issue of noise didn't arise.

With later computers I too experienced it, and only eliminated it by using balanced cables from interface to speakers, something I'd not had to do (or even thought to do) before.

Unfortunately, you do not have the option of using balanced. Although you have TRS at one end, you have unbalanced RCA at the other. But you might consider changing the logitech to speakers that have balanced inputs one day.
 
I might be way out of the park here but honestly I would suspect the shielding of the logitecs. If they aren't designed for audio recording monitoring RF from instruments can be an issue.
 
Along those lines, lack of shielding of controllers on the motherboard (like I suspect chipset or USB in this case) can also result in this type of interference. Not much you can do about that if it ends up being the cause.
 
I suspect the Logitek speakers are NOT earthed/grounded. I assume they are powered from a 'wall rat'? You could try a wire from a radiator or water pipe to the RCA sleeve. It is of course possible that you have a poor earth in the building.

The other possibility is a rare but pretty incurable problem with Fire Wire. A few MOBOs had a problem that caused a noise, often termed 'zipper' noise since it was worse when the mouse was moved. One thing you could try is to ensure that all the MOBO mounting screws are present and 'nipped up' tight.

Surprised no one has as yet said "post a clip" ? If you do, it works best FOR ME if you attach a 320K MP3.

Dave.
 
The other possibility is a rare but pretty incurable problem with Fire Wire. A few MOBOs had a problem that caused a noise, often termed 'zipper' noise since it was worse when the mouse was moved.

I think the problem is not that rare. It was what I experienced with my firewire firepod, and some computers I had were worse than others. As I mentioned above, it went away with balanced cables from firepod to speakers.
 
I think the problem is not that rare. It was what I experienced with my firewire firepod, and some computers I had were worse than others. As I mentioned above, it went away with balanced cables from firepod to speakers.

Ah so! Mr G, I recall the debacle in the SoS forum. A computer supplier chipped in to say that if the machine was returned to him there was a 'tweak' that could be done in BIOS. He said he could not make the correction public for "Commercial reasons" . I do not recall the name of the PC supplier but it was none of the 'big' ones.

"Balanced' monitor feeds? Yes, OP could try an Art or Orchid traff box on the output jacks then leave the shield diss'ed at the RCA end and just use 'hot and cold pairs.

Hum loops and other associated noises are often easy to solve 'on site'. BLOODY hard by remote control!

Dave.
 
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