SOUND ON SOUND

[BigDeano]

Hey guys, apologies if this is the wrong board, seemed like it may be relevant here.

I am having problems with a very large amount of noise getting into the audio path from my externals screens.

I’m plugging them into my 2018 MacBook via USB-C to HDMI cable. I am also using the extra expansion USB ports on the monitors, so they have a 2nd cable connecting them to my main hub to give me more ports.

I was trying to use my Orban spring reverb today, which has been in storage since before I got the screens, but the noise makes it totally unusable. However when I unplug the usb expansion cable, the noise drops significantly, and then when I unplug the HDMI cable, the strange computer interference noise completely goes, and I’m left with a manageable level of mains hum. Which in a perfect world wouldn’t be there either, but hey, I’ll be happy without the sound of digital hell!

I’m running everything from a few extension leads, which are plugged into to each other, and back to one plug socket.

I shot a couple of quick videos as it’s a lot easier to show you what’s going on!

https://youtu.be/ranCbWvjrmQ

https://youtu.be/XEAqIk_8AuQ


I also had this to a lesser degree the other day when I was recording some hardware synths and connected them via usb. As soon as I unplugged all connections from the screens, the noise went away.

Does anyone know what might be causing this and if there is any way of getting rid of it? It’s driving me mad!

Any help would be massively appreciated!

[CS70]

Hi there,

it is most likely a grounding issue. There have been a couple posts on the subject lately with some hints on how to fix issues like yours.

The first thing is, is everything that has a three-pronged plug attached to same wall socket (via a multiple-socket extension, of course)?

If not, try that. :)

[Wonks]

I’m running everything from a few extension leads, which are plugged into to each other, and back to one plug socket.

So yes, CS70.

[CS70]

Right, thanks Wonks, hadn't caught that one.

@BigDeano, you could have a look at this page: https://support.native-instruments.com/ ... ng-Noises-

It's for native instrument kit but the instructions are pretty generic.

[BigDeano]

Thanks for the link @cs70.

Had a look but it’s all pretty standard stuff, I’m pretty sure I’m following best practices with the way that everything is plugged in etc.

The ground loops are definitely occurring when I plug the screens in, so at least I kinda know where they’re coming from. I’m really not sure of the solution though!

[BigDeano]

I’m wondering if modifying the usb cables to cut the ground on them might help? Not really sure how this works but have seen it mentioned in a few places. Also don’t know if I would be able to do that with the usb-c to hdmi cable easily.

Also also, am I being dense....Where has the forum search gone? Or is it just not available on IOS?

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[Wonks]

Top right ‘hamburger’ , then the plus sign by ‘forum’ and search is an option there.

[merlyn]

Do you only get noise when the spring reverb is connected?

Do you get noise if you disconnect the spring reverb and go straight from your audio interface out into your monitors?

[BigDeano]

Do you only get noise when the spring reverb is connected?

Do you get noise if you disconnect the spring reverb and go straight from your audio interface out into your monitors?

Hey Merlyn, no noise if I’m just monitoring through the interface/speakers. I do get noise when using the spring, or when I connect a synth with USB midi.

[merlyn]

OK. So in theory you shouldn't get noise if the audio path is balanced throughout. The problem then would be the back of the Orban.

The input is unbalanced.

When connecting balanced to unbalanced it's recommended to leave the screen off at one end. I see the screen and cold are both connected to the same terminal at the back of the Orban.

The solution I think would be a transformer isolator in all the unbalanced connections.

[BigDeano]

OK. So in theory you shouldn't get noise if the audio path is balanced throughout. The problem then would be the back of the Orban.

The input is unbalanced.

When connecting balanced to unbalanced it's recommended to leave the screen off at one end. I see the screen and cold are both connected to the same terminal at the back of the Orban.

The solution I think would be a transformer isolator in all the unbalanced connections.

Thanks Merlyn! I’ve got a Pyle mini hum eliminator, so I’ll try placing that in between the output of the interface and the orban and see if that helps!

Could I just remove the screen from the terminal on the orban? Forgive my non existent knowledge of wiring! I really need to understand this stuff, but it never sinks in!

Will let you know how it goes!

Cheers dude!

[CS70]

Thanks for the link @cs70.

Had a look but it’s all pretty standard stuff, I’m pretty sure I’m following best practices with the way that everything is plugged in etc.

The ground loops are definitely occurring when I plug the screens in, so at least I kinda know where they’re coming from. I’m really not sure of the solution though!

Sorry, forgot about this.

If your grounding is fine, the issue could be EMI. I heard many people over the years having issues with EMI using HDMI cables, often due to the way that the shield is attached to the connector by the manufacturer (see http://www.magazines007.com/pdf/DC08_Dana_Bergey.pdf)

Since the assembly is usually sealed and fused together, it's practically impossible to say if a cable is good or not by just looking at it. From outside, they look all the same. USB suffers from a similar problem even if to a lesser degree, and that I have experienced myself.

Incidentally I suspect that an issue that has been occurring last month in my HDMI wireless sender/receiver setup may also be due to that, as I swapped the HDMI cable at the TV end without much thought, and the signal has become much more noisy (thus requiring much shorter distance to work). Unfortunately the TV is in the wall and it's a mess to take down, so the issue stays until I have time and will to fix it.

In short, you could try your luck with a few different HDMI cables.

[BigDeano]

Thanks for the link @cs70.

Had a look but it’s all pretty standard stuff, I’m pretty sure I’m following best practices with the way that everything is plugged in etc.

The ground loops are definitely occurring when I plug the screens in, so at least I kinda know where they’re coming from. I’m really not sure of the solution though!

Sorry, forgot about this.

If your grounding is fine, the issue could be EMI. I heard many people over the years having issues with EMI using HDMI cables, often due to the way that the shield is attached to the connector by the manufacturer (see http://www.magazines007.com/pdf/DC08_Dana_Bergey.pdf)

Since the assembly is usually sealed and fused together, it's practically impossible to say if a cable is good or not by just looking at it. From outside, they look all the same. USB suffers from a similar problem even if to a lesser degree, and that I have experienced myself.

Incidentally I suspect that an issue that has been occurring last month in my HDMI wireless sender/receiver setup may also be due to that, as I swapped the HDMI cable at the TV end without much thought, and the signal has become much more noisy (thus requiring much shorter distance to work). Unfortunately the TV is in the wall and it's a mess to take down, so the issue stays until I have time and will to fix it.

In short, you could try your luck with a few different HDMI cables.

Thanks for this cs70! I’ll try a bit more trouble shooting tomorrow, and see if I still get noise if I just have the xtra ports USB ports from the screens plugged in.
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[merlyn]

Could I just remove the screen from the terminal on the orban?

You could try it.

I don't think XLR pigtails are the best for an unbalanced input. An unbalanced cable with a shield can pick up interference, so with the pigtails you have a length of unbalanced cable without a shield. I would think that would pick up interference.

If I was wiring this I would try to keep the length of unbalanced cable without a shield as short as possible.

[BigDeano]

Could I just remove the screen from the terminal on the orban?

You could try it.

I don't think XLR pigtails are the best for an unbalanced input. An unbalanced cable with a shield can pick up interference, so with the pigtails you have a length of unbalanced cable without a shield. I would think that would pick up interference.

If I was wiring this I would try to keep the length of unbalanced cable without a shield as short as possible.

Yeh that is a fair point Merlyn. I do also have to wiggle the cables around on the back sometimes as they randomly cut out. Any suggestions on how best to wire up those terminals?

Thanks again for your advise!
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