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Digital audio noise from PC

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Digital audio noise from PC

Postby Marbury » Fri Apr 03, 2020 6:07 am

This is driving me mad with this new PC. I am using the same Native Instruments K6 but when I turn on the same old studio monitors or monitor live audio coming into the AI via the inputs I can hear a high frequency digital noise that is driving me mad. Its like a random high frequency Morse code is the best way to describe. I made a video feeding the phones output into my Nikon digital slr camera's mic input and it's very loud on that when the music is quiet. For the life of me I cannot fathom what is causing it as I don't remember it being this bad on the old pc.

Nothing has changed with my set up except a new PC build on Windows 10.
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Re: Digital audio noise from PC

Postby Arpangel » Fri Apr 03, 2020 7:04 am

Marbury wrote:This is driving me mad with this new PC. I am using the same Native Instruments K6 but when I turn on the same old studio monitors or monitor live audio coming into the AI via the inputs I can hear a high frequency digital noise that is driving me mad. Its like a random high frequency Morse code is the best way to describe. I made a video feeding the phones output into my Nikon digital slr camera's mic input and it's very loud on that when the music is quiet. For the life of me I cannot fathom what is causing it as I don't remember it being this bad on the old pc.

Nothing has changed with my set up except a new PC build on Windows 10.

I had exactly this problem a few years back, but....I"m sorry, I can’t remember what caused it!
I’m almost sure it was a ground loop problem, of some sort, in either the mains wiring or signal cabling. Maybe worth re-routing cables, and checking your earthing arrangements, plug-boards etc.
Also, sometimes routing cables near a computer screen can cause problems like this.
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Re: Digital audio noise from PC

Postby ef37a » Fri Apr 03, 2020 8:53 am

If you disconnect the monitors from the KA6 and listen to it via headphones do you still get the noise? If not you almost certainly have a ground loop problem. Do the usuals, make sure all mains plugs are 'starred' from a common socket. Try removing the screen from the monitor cables one end. Might need a transformer box.

I suspect though that this is not a ground loop, why would one suddenly appear if the basic setup is the same?

The computer is a "new build", by you? If so check earth paths. Are USB cases actually bonded to the casing? One problem I had some years ago was a missing MOBO mounting screw (always M3?) . Check they are all present and tight and that the solder pad they clamp actually contacts the screw. Should be very low resistance, typically 0.7 Ohms on a digital meter.

Same USB cable to the KA6? If so try to find one with a ferite 'lump' in it. And of course, if you can beg/borrow some scabby laptop that will prove the PC guilty or not.

Dave.
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Re: Digital audio noise from PC

Postby Wonks » Fri Apr 03, 2020 9:39 am

Wasn't something like this in another post caused by the processor switching speeds? Worth checking some of the other posts in this section about processor speed switching.
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Re: Digital audio noise from PC

Postby Pete Kaine » Fri Apr 03, 2020 1:09 pm

It can be, or it can be noise from spread spectrum settings being disabled. It's one of the things that disabling C-states, eist or other downclocking options can help deal with as anything that causes choking on the voltage delivery stages can cause this to exhibit.

I would however also look to test for loops as well. Disconnect everything except the interface, mouse, keyboard, monitor and headphones (yes, disconnect the speakers) and see if the audio interface is still doing it. You can also disconnect the screen at this point as I've seen that too in the past.
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Re: Digital audio noise from PC

Postby Marbury » Fri Apr 03, 2020 2:03 pm

Ok, I have hooked up all the same cables, in the same order to the old PC (Pete built at scan) and its as quiet as a mouse. So the problem is with the new PC. Obviously it hasn't been optimised for use as an audio workstation (which I now deeply regret as I paid more in the long run sourcing the parts from Amazon and paying the young computer savvy acquaintance to put it together, but I will have to live with that) So is there something I can do to change in bios etc ?
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Re: Digital audio noise from PC

Postby The Elf » Fri Apr 03, 2020 2:49 pm

Marbury wrote:I now deeply regret as I paid more in the long run sourcing the parts from Amazon and paying the young computer savvy acquaintance to put it together...
This is why I buy from Scan. It costs a bit more in the short term, but it saves you more in the long term.
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Re: Digital audio noise from PC

Postby Agharta » Fri Apr 03, 2020 3:40 pm

There are different types of coil whine but it doesn't usually affect the audio output as it's just a localised noise, which can still be annoying but in a different way.

Try running the PC using the "High Performance" Power Plan as that can mitigate some types of coil whine.
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Re: Digital audio noise from PC

Postby James Perrett » Fri Apr 03, 2020 3:55 pm

Marbury wrote:Ok, I have hooked up all the same cables, in the same order to the old PC (Pete built at scan) and its as quiet as a mouse.

But have you done as Pete suggested? We won't get anywhere until you start following suggestions rather than doing random things that get you nowhere. The grounding has obviously changed so what you need to do now is to work methodically to see what works.

Changing the BIOS is just clutching at straws at this stage. The first thing to do is to strip things back to just the computer and interface as Pete suggests and work from there.
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Re: Digital audio noise from PC

Postby AlasdairEaston » Fri Apr 03, 2020 4:33 pm

I think we might be having the same problem. Although I had to pause trying to solve it due to preparations for the apocalypse, and getting my old Dad and very old great-auntie ready and stocked up.

The problem sounds the same: the old PC (laptop) was great but was hitting it's limits. Electrically silent though. I never gave it a thought. The new PC, an absolute cracker (custom built for audio production) is great but has the digital noise problem you mention. Like some super-high-speed modem/data transmission type sound. It alters based on what I do, varying with processor load, or what's happening on-screen, like scrolling some text in a window. It is not a quiet noise either. Very prominent. Interestingly running LatencyMon changes it from a chaotic noise to a steady-ish whine. Do you get the same?

Working with the suppliers, they suggested a ground loop was the likely cause, especially after running the LatencyMon test for some reason.

I have gone through all the standard processes, like running all power in a star formation, ultimately coming from a single wall outlet. Removing as much hardware as I can from the system while diagnosing it, etc. I need to re-visit where we got to, because it was all getting really subtle and complex. For example, removing USB cables from various points helped, but just touching the end of the USB cable to various pieces of metal (USB sockets, other audio connectors elsewhere on the back of the interface, etc.) changed the sound.

In short, between the supplier (who has been great) and I, we hadn't completely nailed it before the Corona virus turned the world on its head. However, the system is in a state that I can use in the meantime. What helped was this:
1. Using an ART DTI box https://www.soundonsound.com/reviews/art-dti between the interface and my active monitor.
2. Using XLR cables in places where I was previously using instrument cables.

What seemed to make no difference was rearranging the power supplies to all come from the same outlet. To be fair, I was only using two outlets before, but I know it's good practice to use one, so I've left it that way.

I confess, I'm worried that I now have a system that can only work well when things are connected by special boxes, isolators, relatively expensive XLR cables, etc. What happens when I just want to plug in something that only has a TRS connection? Does that means a new isolator box, for example? I've gone from having a silent studio to one that seems to be alive with noise unless I'm really careful. Maybe I was just lucky before and everyone who's been doing this for a long time has found out what I'm just learning.

One point the suppliers made was that moving to a bigger power supply can cause these sorts of problems. It's true that the power supply of this new PC is far beefier than my old laptop. Is that the case for you too?

Watch out for dodgy cables as well. My situation was clouded by a brand new XLR cable connector being faulty. That caused all sorts of head-scratching until i accidently knocked the connector and the noise improved a hundred times.

I'll be interested to see how you get on with yours. Working through it methodically as James suggests is the only way.
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Re: Digital audio noise from PC

Postby Watchmaker » Fri Apr 03, 2020 4:40 pm

I have experienced a constant whine on USB peripherals when using docks. It seemed intermittent if I moved around a lot because I was in an untreated room!

As it goes away when plugged direct, I assume either the dock isn't regulating voltage well or isolates the power out. If you're using a dock, try swapping cables around, might be one lesser quality bit of wire :-)

You've done the USB root hub optimizations in device manager?
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Re: Digital audio noise from PC

Postby Hugh Robjohns » Fri Apr 03, 2020 5:00 pm

Ground-loops in and of themselves aren't a problem. Noise currents will always flow around the Faraday cages (outer cases) of equipment and thus between devices via the connecting cables.

Provided the equipment is designed correctly, these currents should never get anywhere near the audio circuitry or audio ground references, so shouldn't cause any problems.

Everyone blames their computers when they hear computer-related noises, but the audible noise can only be generated in something with audio circuitry which is deriving its ground reference from a noisy ground. In other words, the computer isn't really the problem: it's actually the interface or active speakers that are picking up the unwanted noises.

Sure, some computers dump more noise into the ground than others, depending on the components used and the physical construction... but in a properly designed system that shouldn't make any difference at all!

Tracking down the sources of ground-loop noises can be mind-blowingly complicated and confusing which is why you have to start from the simplest possible system. Get that quiet, and then expand it bit by bit, checking and fixing as you go.

So always start with just the interface and computer and listen with headphones.

Usually, the problem is between the interface and active monitors... and hence using a line isolator box or isolating the cable screen between the interface and monitors often fixes the problem.

But bear in mind that even with that specific loop fixed, it's perfectly poissible to create another loop when you plug in something else.

And worse, if you plug in two or more devices at the same it's quite possible for their circulating ground currents to cancel each other out, so the system might appear to be problem-free when it really isn't! Or worse, it's quiet until you unplug something... or quiet until you change the type or length of a connecting cable.... :crazy:

Hence the advice to add each device one at a time and check/fix each one in turn.
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Re: Digital audio noise from PC

Postby Marbury » Fri Apr 03, 2020 7:09 pm

Sorry folks, been out all day helping mother who is currently bedridden so haven't had time to start the process of elimination yet. What I will say is when the signal from the headphone output of the K6 was fed into my camera the noise was very prominent. But listening at full volume via headphones is quiet.
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Re: Digital audio noise from PC

Postby Marbury » Tue Apr 28, 2020 7:57 pm

Ok, I have disconnected everything bar the AI, changed the usb cable to the AI and the noise still persists. Its weird because the signal is clean listening through headphones via the K6 phones, but when I fed signal direct from the K6 phones to the video camera (where the offending noise recorded) you can hear it on the video. Absolutely no idea why it should do this as the K6 is quiet on the older PC.

This new Intel Z390 D Motherboard even has a high quality audio component, The processor is an i5-9600KF if that helps.

And incidentally, why with such a higher spec system do I get clicking and popping on some of the more complex sounds like "Big Boomer" in Omnisphere ? The audio isn't clipping or anything like that. Its just seems to never like the big percussive hit sounds
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Re: Digital audio noise from PC

Postby Hugh Robjohns » Tue Apr 28, 2020 9:03 pm

Marbury wrote:Its weird because the signal is clean listening through headphones via the K6 phones, but when I fed signal direct from the K6 phones to the video camera (where the offending noise recorded) you can hear it on the video. Absolutely no idea why it should do this as the K6 is quiet on the older PC.

Would it be safe to assume the camera is powered from the mains?

If so, you have a simple ground-loop problem. A line isolation transformer box in the feed to the camera should cure it.
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