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Troublesome PC digital chatter picked up by electric guitars

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Troublesome PC digital chatter picked up by electric guitars

Postby ian2 » Sat May 16, 2020 12:45 am

Just over a year ago, after 10 years of home recording using a Dell Vostro desktop and an E-MU 1616m interface, I switched to a late-2018 Dell Optiplex 3060 desktop (Windows 10) and a Steinberg UR242 USB interface. The latter is powered by a wall wart.

Having a young son, it has only been recently that I've been sufficiently active with this new gear to realise that when I have an electric guitar (e.g. an American standard Stratocaster) connected to the UR242 the audio signal from the UR242's headphone output includes an annoying amount of noise. The level of this noise increases profoundly as the distance between the guitar and the PC is decreased; according to my mental model (which might be flawed), it seems clear that the noise (EMI? RFI?) is emanating from the electronics in the PC and being picked up by the guitars magnetic pickups. The nature of the noise could be described as "digital hash"; it's clearly related to whatever work the PC is doing at the time.

I didn't experience this issue with my previous equipment, nor with the equipment with which I made my first forays into PC-based home recording, c. 2000.

Having done a bit of Googling, I have wondered whether there is a ground loop somewhere in my equipment. However, I've paired down the plugged-in equipment to the following, without success in identifying/eliminating a ground loop.

Multi-way mains adapter plugged into a mains wall socket.

Dell Optiplex 3060 plugged into the multi-way.
Wired USB mouse
Wired USB Dell keyboard
Cubase USB dongle

Samsung LU28E590DS monitor plugged into the multi-way, connected to the PC via DisplayPort cable.

Steinberg UR242 plugged into the multi-way, connected to the PC via USB cable.

Stratocaster connected by a regular guitar cable to the audio interface's "INPUT 1", with the Hi-Z enabled.


I've even unplugged the monitor from the mains, after getting ready to record.

As you might imagine, the problem is exacerbated if I introduce a source of gain to the signal from the Strat; e.g. inserting a Joyo British Sound pedal between the guitar and the audio interface.

I've tried introducing a Behringer GI-100 DI box between the guitar and the audio interface (with the Hi-Z mode disabled on the interface).

The only amount of progress I've seen so far is a slight reduction in noise after disabling a number of fancy BIOS features which are concerned with varying power management and CPU speed.

The following recordings when I was using my Strat's bridge pick-up demonstrate the noise:
"Fancy features" enabled: https://drive.google.com/open?id=1MdcKS ... KIYjZBAO10

"Fancy features" disabled: https://drive.google.com/open?id=1p9idt ... hxnrFxhhfo

Towards the end of the recordings I swivelled a bit on my chair, to demonstrate the antennae-like effect of orientation of the guitar, then moved the guitar right next to the PC case.

During the initial part of the recordings the guitar's pickups were, at a guess, a little under two feet from the nearest part of the PC case. Whilst it's obviously possible to be further from the PC when recording, I've always been used to recording this close to my PC in the past. As you can imagine, it's very convenient for allowing operation of the DAW.

I'd really appreciate some ideas about what I can try next.
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Re: Troublesome PC digital chatter picked up by electric guitars

Postby ian2 » Mon May 18, 2020 11:06 pm

I have now tried the following, without any noticeable improvement:

1. Various changes to Windows' power plan.
2. Fed the multiway adaptor from an extension lead plugged into a socket in a different room..
3. Used a different multiway adaptor.

I'd still welcome ideas for reducing the noise.

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Re: Troublesome PC digital chatter picked up by electric guitars

Postby CS70 » Mon May 18, 2020 11:47 pm

Well, pickups... pick up all sorts of interference. There may not be anything especially bad in your set up, but changing computer may simply have been altered the EM fields around that areas so that they are more visible to the pickup. Different components, leds, internal shielding - anything can contribute. Even something as simple as having used a different extension cord with an illuminated on-off button, or a new fluorescent lamp on the desk.

Obviously you may have also grounding and electrical problem but they would likely show up in much more than just your pickups.

What to do? There's the story of the guy going to the doctor and saying "hey, if I lift my left arm, it hurts" and the doctor replying "then don't".

Get yourself a longer cable if needed, and stay well away from the screens and other sources of interference. :-)
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Re: Troublesome PC digital chatter picked up by electric guitars

Postby wireman » Tue May 19, 2020 12:03 am

Does this help...

https://www.proaudioland.com/news/deali ... erference/

I did see some comments on other models in that range creating audio issues based on the Ethernet interface and drivers but am not sure it is the same issue.

I hesitate to suggest it but I suppose if you are desperate you could try putting it in a metal biscuit tin (but it will be hard to have no gaps) to see if that helps but don't let it overheat.
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Re: Troublesome PC digital chatter picked up by electric guitars

Postby Mike Stranks » Tue May 19, 2020 8:55 am

Hi Ian

... very long time no see...

I think CS70 has summed it up... the guitar pick-ups 'picking up' bits and pieces of EMI radiating from the PC.

This may not be possible, but I'd be looking at moving the PC itself further away from you, but keeping the screen, keyboard and mouse where they are.

I use wireless keyboard and mouse so that should be straightforward. And a longer DVI/HDMI cable shouldn't be too difficult either.
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Re: Troublesome PC digital chatter picked up by electric guitars

Postby ian2 » Thu May 21, 2020 10:54 pm

Mike,

Huge thanks for your post - I have to confess (blush) that it simply hadn't occurred to me to move the PC further away! The PC is currently sitting on the bottom shelf of my cheap and cheerful computer trolley/desk, so your post has made me think it's time either to move it onto the floor, further away, or to get a desk sufficiently bigger that I can keep it off the floor but further from where I sit. Working from home every day has made me want a bigger desk, and there's always scope for experimenting with the PC's position to see how much bigger a desk would need to be to get the PC sufficiently far away that the EMI is insignificant.

Although I still had a couple of things to try, namely USB cables with ferrite chokes, and using HDMI rather than DisplayPort to connect my monitor to the PC, I think relocating the PC is likely to be the change that makes the difference.

Incidentally, I suspect that, when selecting a new PC, most seasoned amateur recordists expect the risk of DPC-related pops and crackles to be the most difficult thing to gauge. I, for one, certainly hadn't anticipated this PC being a considerably greater source of EMI than my previous Dell.

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Re: Troublesome PC digital chatter picked up by electric guitars

Postby ef37a » Fri May 22, 2020 12:52 am

Are you totally sure the casing of the PC is securely bonded to mains earth and are you sure your mains earth is a good one? The latter is probably ok since the previous kit was quiet.

Is the pup/controls cavity in the guitar screened and bonded?

Son used a Mex Strat within a mtr or so of an HP and we just used to get a bit of 100Hz hum and swinging the guitar around nulled that.

Dave.
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Re: Troublesome PC digital chatter picked up by electric guitars

Postby wireman » Fri May 22, 2020 6:29 pm

ef37a wrote:Are you totally sure the casing of the PC is securely bonded to mains earth and are you sure your mains earth is a good one? The latter is probably ok since the previous kit was quiet.
.

I thought it possilble that the particular model mentioned has a wall wart so by no means a given that there is a ground.
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Re: Troublesome PC digital chatter picked up by electric guitars

Postby ef37a » Fri May 22, 2020 6:38 pm

wireman wrote:
ef37a wrote:Are you totally sure the casing of the PC is securely bonded to mains earth and are you sure your mains earth is a good one? The latter is probably ok since the previous kit was quiet.
.

I thought it possilble that the particular model mentioned has a wall wart so by no means a given that there is a ground.

You are absolutely right Wireman, I missed that.

OP..Get GROUNDED!

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Re: Troublesome PC digital chatter picked up by electric guitars

Postby ian2 » Mon May 25, 2020 1:08 pm

Dave,

I've measured the resistance between the new PC's case and the earth pin of its kettle lead - it was about 0.7 Ohms. As for the quality of the mains earthing from the wall socket, my researches suggest that it isn't something the average Joe has the equipment to be able to test - shout if you know a simple test that would suffice.

I've noted that the wall wart for my Steinberg UR242 audio interface has a plastic earth pin. That made me wonder whether the new rig might have a deficit, rather than a surplus, of connections to ground?

I tried connecting the UR242 to my newer PC using a USB cable with a ferrite choke. Because of the different connectors at either end, the choke had to be towards the UR242's end of the connection. No discernible improvement.

Using my old set-up - Dell Vostro + E-MU 1616m - I made a recording using my Strat + Joyo British Sound, with similar settings to those used on the previous recordings. It's at https://drive.google.com/file/d/1TMyXl- ... sp=sharing. No PC chatter audible on this one. Just as with the UR242, the 1616m's wall wart has a plastic earth pin.

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Re: Troublesome PC digital chatter picked up by electric guitars

Postby MOF » Mon May 25, 2020 3:14 pm

Son used a Mex Strat within a mtr or so of an HP and we just used to get a bit of 100Hz hum and swinging the guitar around nulled that.
Was that with a lcd type of screen or crt? The former definitely give off that shash type of noise.
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Re: Troublesome PC digital chatter picked up by electric guitars

Postby ef37a » Mon May 25, 2020 3:30 pm

MOF wrote:
Son used a Mex Strat within a mtr or so of an HP and we just used to get a bit of 100Hz hum and swinging the guitar around nulled that.
Was that with a lcd type of screen or crt? The former definitely give off that shash type of noise.

Flat screen monitor. ****in'ell I did have a CRT jobbie but that was back in the days of 3.1 and 95!

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Re: Troublesome PC digital chatter picked up by electric guitars

Postby MOF » Mon May 25, 2020 10:25 pm

Flat screen monitor. ****in'ell I did have a CRT jobbie but that was back in the days of 3.1 and 95!

Dave.
I thought you might be old school because I haven’t had hum interference in years, but plenty of digital shash unfortunately. Given that you don’t have a CRT monitor I’m amazed you only get hum. :D
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Re: Troublesome PC digital chatter picked up by electric guitars

Postby pa28 » Mon May 25, 2020 11:07 pm

All my recordings from the days of 4/2 track tape to going digital aeons ago are all guitar, one of my many guitars used extensively was/is my US '76 Strat, I had crt monitors then and the noise picked up was so bad I had to play 90degs to the screen and move away. This was annoying enough to spend £300 importing Kinman noiseless pickups from Australia.

These are "humbucking" single coil pups and sorted the problem, crt's have all been disposed of ages ago and pups still good, so may be an expensive but simple solution.
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Re: Troublesome PC digital chatter picked up by electric guitars

Postby ef37a » Mon May 25, 2020 11:37 pm

MOF wrote:
Flat screen monitor. ****in'ell I did have a CRT jobbie but that was back in the days of 3.1 and 95!

Dave.
I thought you might be old school because I haven’t had hum interference in years, but plenty of digital shash unfortunately. Given that you don’t have a CRT monitor I’m amazed you only get hum. :D

Ah well, the level of hum was no worse that you would get with an amp but being a hi fi buff I do not like HUM! I even modded my son's HT-20 because of a residual hum, transformer coupling. Son did not complain about it and neither, AFAIK have thousands of customers!

Dave.
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