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PC sound in signal path

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Re: PC sound in signal path

Postby Leftyjay » Sat Aug 17, 2019 10:54 pm

James Perrett wrote:
Leftyjay wrote:Self built indeed. I think, if we are going that route, is important to know that both side of the pc is closed with tempered glass (and not steel or something similar).

It may look pretty but that certainly isn't going to help create a noise free studio. You need a decent metal enclosure all around with all the panels properly grounded so that no electromagnetic fields can leak out. A large expanse of glass on either side is likely to let all kinds of nasty signals out into the studio.

Yeah, I realized that once the part was ordered and all.

Fyi, heres the noise withtout the pc in the equation (pc off completly, sound was coming from the 11r amp sim, although im not playing in the video). Btw, it was a different guitar (i have more than a few :) ).

https://youtu.be/g_HVrGKi8QE.

We dont here that wierd noise, as expected. BUT, theres a fair amount of noise nonethless. Like I have 2 different issues...

About the panels : should I consider changing the case or I can "patch it"? I dont care it looks like shit honestly
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Re: PC sound in signal path

Postby CS70 » Sat Aug 17, 2019 11:44 pm

Leftyjay wrote:
Self built indeed. I think, if we are going that route, is important to know that both side of the pc is closed with tempered glass (and not steel or something similar). Furthermore, as I'm typing, if I move the mouse around (WIRED mouse), I can hear a variation of the artifact that I hear in the signal. For some reason, the noise gate within BIAS FX2 (or any other VSTs) is blocking that artifact if I'm playing with my headphones, but will go through the Atomic, even with all VSTs closed.

Hm then, there you have it. I'm not an expert but in my pc building period (admittedly quite some time ago) I've seen this a few times. Something is emitting electromagnetic interference from your brand new PC and your guitar, cable or whatever is acting as an antenna.

It can be a number of things: from something as simple as the screen connector (once I found it was a VGA port) to any of the internal components.

Since a Faraday cage stops the RF, you can test this by (don't laugh) covering it with plastic and aluminium foil - google it. Not a long term solution (at least aesthetically) but it will confirm or not if that is the issue.

If it is, you've got to painstakingly debug what part is creating the problem.. hopefully it's not the sum of the parts that does (CE RF certification is based on individual components but unfortunately its not necessarily so that the together they comply).
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Re: PC sound in signal path

Postby CS70 » Sat Aug 17, 2019 11:47 pm

Leftyjay wrote:
Fyi, heres the noise withtout the pc in the equation (pc off completly, sound was coming from the 11r amp sim, although im not playing in the video). Btw, it was a different guitar (i have more than a few :) ).

https://youtu.be/g_HVrGKi8QE.

We dont here that wierd noise, as expected. BUT, theres a fair amount of noise nonethless. Like I have 2 different issues...

That sounds like more RF, only constant. Typically a lamp, a neon tube or other device. Even the little lights in extension cords rocket switches can create that. Does the sound change if you move about - especially if you rotate on your axis?
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Re: PC sound in signal path

Postby Leftyjay » Sun Aug 18, 2019 12:44 am

CS70 wrote:
Leftyjay wrote:
Self built indeed. I think, if we are going that route, is important to know that both side of the pc is closed with tempered glass (and not steel or something similar). Furthermore, as I'm typing, if I move the mouse around (WIRED mouse), I can hear a variation of the artifact that I hear in the signal. For some reason, the noise gate within BIAS FX2 (or any other VSTs) is blocking that artifact if I'm playing with my headphones, but will go through the Atomic, even with all VSTs closed.

Hm then, there you have it. I'm not an expert but in my pc building period (admittedly quite some time ago) I've seen this a few times. Something is emitting electromagnetic interference from your brand new PC and your guitar, cable or whatever is acting as an antenna.

It can be a number of things: from something as simple as the screen connector (once I found it was a VGA port) to any of the internal components.

Since a Faraday cage stops the RF, you can test this by (don't laugh) covering it with plastic and aluminium foil - google it. Not a long term solution (at least aesthetically) but it will confirm or not if that is the issue.

If it is, you've got to painstakingly debug what part is creating the problem.. hopefully it's not the sum of the parts that does (CE RF certification is based on individual components but unfortunately its not necessarily so that the together they comply).

Ill try the aluminium trick.
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Re: PC sound in signal path

Postby Leftyjay » Sun Aug 18, 2019 12:45 am

CS70 wrote:
Leftyjay wrote:
Fyi, heres the noise withtout the pc in the equation (pc off completly, sound was coming from the 11r amp sim, although im not playing in the video). Btw, it was a different guitar (i have more than a few :) ).

https://youtu.be/g_HVrGKi8QE.

We dont here that wierd noise, as expected. BUT, theres a fair amount of noise nonethless. Like I have 2 different issues...

That sounds like more RF, only constant. Typically a lamp, a neon tube or other device. Even the little lights in extension cords rocket switches can create that. Does the sound change if you move about - especially if you rotate on your axis?

I tried turning and moving, it does sometimes affect how I here that sound, but its not consistent.
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Re: PC sound in signal path

Postby Leftyjay » Sun Aug 18, 2019 12:54 am

Update : Although I still hear the anyoing PC sound when playing with my headphones, it is MUCH LESS noticeable, even with the noise gate of, to a point where I can live with it (until I'm ready to do some serious tracking).
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Re: PC sound in signal path

Postby CS70 » Sun Aug 18, 2019 9:39 am

Great to hear. Since moving about has changed things, it can be that it was not so much the pc emitting too much RF but some other component (typically cabling, soldering) which is not shielded enough and acts as an antenna. Jacks etc would typically change their position a bit and change these receiving properties..

The fact that the sound change when you move seem to confirm it's EM interference.
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Re: PC sound in signal path

Postby Wonks » Sun Aug 18, 2019 10:28 am

Can you try a long guitar lead and a headphone extension cable and play in a different room to the PC to get as far away from the PC as possible?

EMGs will happily drive a longer guitar lead without treble loss, so you should then be able to tell if it's definitely the guitar itself picking up the noise, or else it's another component like the lead.
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Re: PC sound in signal path

Postby Leftyjay » Sun Aug 18, 2019 12:38 pm

Theres 2 types of interferance going on here :

In the first video, you hear both : the digital, almost morse codish sound. That sound remains constant, wether i move or not.

In the second video, that interference will get amplified if I move at a certain angle.


Thanks for your replies guys, super helpful. I guess I have some homework to do. Ill try a few things next week and report back ! I realized late yesterday that i could try the same setup with a different pc, my old laptop
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Re: PC sound in signal path

Postby Leftyjay » Sun Aug 18, 2019 12:39 pm

Wonks wrote:
EMGs will happily drive a longer guitar lead without treble loss, so you should then be able to tell if it's definitely the guitar itself picking up the noise, or else it's another component like the lead.

Remember that those sounds can be heard even without a guitar plugged in
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Re: PC sound in signal path

Postby Hugh Robjohns » Sun Aug 18, 2019 8:52 pm

Leftyjay wrote:Even if the Atomic amp is off? I mostly play through headphones, with the Atomic amp at off.

Yes. It's not about whether the amp is on or off. It's the physical connection to it that makes the Ground loop. The connection via the audio connection cable's screen and the amp's mains safety earth.

The transformers in the isolation box break that direct connection and thus remove the ground loop.

If you mostly use headphones, then try unplugging the audio feed to the amp, or unplugging the amp from the mains outlet. If the unwanted noise is due to a ground loop I will go away when you unplug the amp.

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Re: PC sound in signal path

Postby Leftyjay » Mon Aug 19, 2019 4:00 am

I will check more in depth this week, but FYI, when I unplug the USB cable in the back of the eleven rack, both anyone noises goes away completely.
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Re: PC sound in signal path

Postby CS70 » Mon Aug 19, 2019 6:41 am

Leftyjay wrote:I will check more in depth this week, but FYI, when I unplug the USB cable in the back of the eleven rack, both anyone noises goes away completely.

Many cheap USB cables aren't shielded well or at all, which could be the source of your problem, or at least a contributing factor if they act as an antenna. The challenge is that it's hard to say which ones are which without measuring or opening them up - price alone is not a proxy for quality unless you get the ones which gold-plated connectors which are very expensive (and even then). You could try to google for specific brands.

Worth a try if you have other cables laying about.
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Re: PC sound in signal path

Postby ef37a » Mon Aug 19, 2019 8:40 am

Late on parade I know but these,
https://www.amazon.co.uk/AV-Link-Ground ... th=1&psc=1

Are surprisingly good for the money. They are cheap enough to buy in as a test device and if they fix the earth loop problem, fork out for better. Note, although the audio performance might not be top class they do just as good a job of isolating grounds as expensive transformers. (but then this IS only guitars!)

Point about self built PCs. Check that all the MOBO mounting screws are present and correct. Even if they are, check with a meter that the PCB pad is indeed grounded by the screw, a layer of resist can prevent this and, AFAIK the EM spec' of a computer depends upon complete bonding of the MOBO ground plane to the case? (Please do NOT tell me you embarked on PC fettling without a DMM?!)

Also, if chicken foil fixes the PC radiation you could seek out some Perforated Zinc. Still see the pretty lights through it but the holes are around 1.5mm so a "stop" up to several Gigs.

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Re: PC sound in signal path

Postby ef37a » Mon Aug 19, 2019 8:49 am

CS70 wrote:
Leftyjay wrote:I will check more in depth this week, but FYI, when I unplug the USB cable in the back of the eleven rack, both anyone noises goes away completely.

Many cheap USB cables aren't shielded well or at all, which could be the source of your problem, or at least a contributing factor if they act as an antenna. The challenge is that it's hard to say which ones are which without measuring or opening them up - price alone is not a proxy for quality unless you get the ones which gold-plated connectors which are very expensive (and even then). You could try to google for specific brands.

Worth a try if you have other cables laying about.

I have a couple of USB A to Bs that have a transparent cover so it is obvious that they have a shield, a good quality braided shield in these cases (these are clear but I have seen red and blue see thru' jobbies) . Another trick is to try some clip on ferrites. Maplin (GRTS. Joney Mitchell had it right!) used to do a range but I dare say 'Zon have them.

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Re: PC sound in signal path

Postby Hugh Robjohns » Mon Aug 19, 2019 9:46 am

Leftyjay wrote:...but FYI, when I unplug the USB cable in the back of the eleven rack, both anyone noises goes away completely.

Yes, I appreciate that... but it's very hard to break a ground loop via a USB cable, and much easier via the audio cables feeding other equipment...

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Re: PC sound in signal path

Postby CS70 » Mon Aug 19, 2019 10:14 am

Browsed thru the thread and just realized you gave an important clue some posts ago - the sides of your pc case aren't metal but acrylic or glass.

If they're large enough (as they probably are) they will break the Faraday cage made by the case by and cause EMI in the surrounding space. Basically anything that's not a metal case will do that.

In that case, for your playing moments you can simply build a little shield made by aluminium on a light wood frame enclosed in plastic sheets (plastic foil works fine even if ugly :)) and attach it on the side with velcro, so you can remove it when you want the pc to look good.

Also, some motherboards also have options to reduce immediate interference ("spread spectrum") - you could check if yours have it and turn it on in the BIOS.

Good advice on possible ground loops and screws properly set as well. But a non-metal case will cause RFI in almost all cases.
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Re: PC sound in signal path

Postby Leftyjay » Mon Aug 19, 2019 12:51 pm

CS70 wrote:
In that case, for your playing moments you can simply build a little shield made by aluminium on a light wood frame enclosed in plastic sheets (plastic foil works fine even if ugly :)) and attach it on the side with velcro, so you can remove it when you want the pc to look good.

Also, some motherboards also have options to reduce immediate interference ("spread spectrum") - you could check if yours have it and turn it on in the BIOS.

Ill try the setting in the BIOS. as for the case, since the noise goes completely away when simply unplugging the usb cable from the 11r, woulndt that mean that the noise is purely caused by ground loops and not interference (RF, EMI)?
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Re: PC sound in signal path

Postby CS70 » Mon Aug 19, 2019 1:07 pm

Possibly, and could be the issues are related..

by the way, how old is your 11r?
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Re: PC sound in signal path

Postby Leftyjay » Mon Aug 19, 2019 5:58 pm

11R is several years old...but it's irrelevant now since I just bought a Focusrite 2i2. I wanted to buy one to be able to play and monitor in real time at 92khz with low latency. I must say btw, wow. 92khz with less than 5ms and no clipping, that's awesome. I also bought a balance 1/4 cable to hook up the Atomic and the 2i2.

With that being said : the amp still do sounds like crazy, doing all those wierd noises again. Funny though is those noise, even though I was able to control them with the noise gate, are now completely gone when playing with headphones.

I'm getting there I guess.
Next step : now maybe the ART hum eliminator would worth a try since the problem is not there anymore when playing with headphones.
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