PC sound in signal path

[Leftyjay]

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).

[CS70]

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.

[Wonks]

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.

[Leftyjay]

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

[Leftyjay]

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

[Hugh Robjohns]

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.

H

[Leftyjay]

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.

[CS70]

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.

[ef37a]

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.

Dave.

[ef37a]

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.

Dave.

[Hugh Robjohns]

...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...

H

[CS70]

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.

[Leftyjay]

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)?

[CS70]

Possibly, and could be the issues are related..

by the way, how old is your 11r?

[Leftyjay]

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.

[CS70]

The reason I asked is because some of 11 rack's first run had a known grounding issue on the "output to amp" jack.

[Leftyjay]

The reason I asked is because some of 11 rack's first run had a known grounding issue on the "output to amp" jack.

I don't think I have this issue since when I unplug the 11r from the pc, it all goes away. Anyway, I just bought a Focusrite 2i2 and I will keep the 11r has a backup for now.

That whole thing drives me nut, but I realize that I probably have the worst environement. Did I told you that the router is 15 feet away? Not helping the noise issue for sure.

[Leftyjay]

Just in case you still care

I've plugged the computer with a cord extension in another. the PC itself hasn't moved, just where it is connected.

90% of that anyoing noise is gone ! I can live with the rest since the noise was a lot more worse on the Amp vs listening directly through headphones.

[Wonks]

Nice!

It does seem to imply that most of the noise is due to a ground loop, though it is worth checking on the ground connection for the power lead in the original socket, and that the ground for it is connected properly.

Have you got a power socket tester handy?

[Leftyjay]

Nice!

It does seem to imply that most of the noise is due to a ground loop, though it is worth checking on the ground connection for the power lead in the original socket, and that the ground for it is connected properly.

Have you got a power socket tester handy?

Even better. A friend that knows more than me about electricity

Ill check the socket and identify the culprit but in the meantime, ill just buy an extension to connect the pc at the other end of room (room is pretty large)

[Martin Walker]

Ill check the socket and identify the culprit but in the meantime, ill just buy an extension to connect the pc at the other end of room (room is pretty large)

The trouble with this approach is that you won't have broken the ground loop, but simply changed its size. Often this makes the offending noises worse, which is why others in this thread have already suggested plugging in all your gear to a single mains socket via one or more distribution boards.

This won't ''break' the ground loop either, but in most cases making the loop physically smaller results in lower amounts of noise, because the currents are lower.

A case in point - my own small studio is powered via a single mains wall socket, and the only time I've had ground loop noises is when I powered a master keyboard via a mains socket on the other side of the room. As soon as I moved the keyboards's power supply so it could be plugged in with all my other gear, that noise disappeared, and has never come back.

Good luck whatever you decide to do though

Martin

[Leftyjay]

Initially, it WAS already in the same socket. The problem is worst when pluging in the same powerbar. It gets 90% down in noise if the PC is plugged (not moved) to another electrical socket.

[Drew Stephenson]

Initially, it WAS already in the same socket. The problem is worst when pluging in the same powerbar. It gets 90% down in noise if the PC is plugged (not moved) to another electrical socket.

Odd, but if it works...

[Hugh Robjohns]

Ground loops can and often do very strange things and behave in strange ways. It's all to do with the routes the earth current noise flows. Sometimes -- as here -- doing what should be the wrong thing can appear to improve the situation. However, it's not really a cure, it's just that some of the circulating noise currents have partially cancelled each other out. It's actually an indication that there is more than one ground loop affecting the system as a whole!

[Martin Walker]

Ground loops can and often do very strange things and behave in strange ways. It's all to do with the routes the earth current noise flows. Sometimes -- as here -- doing what should be the wrong thing can appear to improve the situation. However, it's not really a cure, it's just that some of the circulating noise currents have partially cancelled each other out. It's actually an indication that there is more than one ground loop affecting the system as a whole!

That's exactly the point I was trying to make Hugh



Martin