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Home noisy cabling setup: can I improve it without changing the cables?

antcollinet

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You might be right, as breaking the loop is standard.
But a wire and touching it to chassis is a good way to envision the ground loops quickly.
How does that work. I assume you mean an earthed wire - but doesn't that then just form part of the ground loop? In parallel with whatever interconnect is carrying it anyway.

I guess it could reduce loop impedance specifically to that device reducing the noise on the input to that device. Expecially if it is connected beteween source and destination rather than directly to an earth point.
 

Holmz

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I guess it could reduce loop impedance specifically to that device reducing the noise on the input to that device. Expecially if it is connected beteween source and destination rather than directly to an earth point.

Yeah that part. Source to destination
Particularly if the the RCAs don’t have much of a wire the negative side, and the OP mentioned 12M long for one set.

In a car I would suggest wielding a jump cable on the dash and some other part, like a divining rod.

if the computer was near the other gear and a star arraignment was possible, then that would be the go, but the 6M and 12M cables suggest it is in another room.
 

antcollinet

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Yeah that part. Source to destination
Particularly if the the RCAs don’t have much of a wire the negative side, and the OP mentioned 12M long for one set.

In a car I would suggest wielding a jump cable on the dash and some other part, like a divining rod.

if the computer was near the other gear and a star arraignment was possible, then that would be the go, but the 6M and 12M cables suggest it is in another room.
On the other hand you also risk creating another loop - source to destination and back to source (through additional wire). You would ideally want to twist the interconnect together with the additional ground wire to minimise this.
 
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fabiospark

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In order to track down the source of the RF noise (NUC itself, video cables (HDMI and USB to HDMI converter), USB cables and so on, a few minutes ago I switched the NUC on so the RF noise started and while listening to the noise in my headphones, I did-:
- moved the NUC a little around [no change in the noise];
- unplugged and re-plugged the HDMI and the USB to HDMI converter from the NUC ports [no change]
- moved the wired mouse [while the cursor were moving a disticnt noise added to the already present one]
- unplugged the USB cable from the NUC to the Focusrite (audio interface) [noise gone completely]
Many USB audio intefaces not only are bus powered (mine it is not) but they need the USB connection in order to function and be able to output audio signals.
To be sure that my interface was properly working even with no USB connection I configured it as a direct passthrough from inputs 1&2 to outputs, then I connected my phone to inputs 1&2 and played some music. With the USB cable connected to the NUC I could hear the music and the noise, withouth the USB connection to the NUC I could hear the music and no noise.

Now I wonder if this is like that because with no USB cable there is no data transmission, hence no RF noice production from either the cable or the NUC case, or because the noise gets generated by the USB cable poor or null shielding: any thought? And any direction?

I tried changing the USB A to USB C cable with a new one but nothing changed.

Should I try and run the USB cable into a metallic conduit grounded on one side only (remember I'm an industrial electrician...) or maybe just wrap it up with an aluminium foil?

Do you know of shielded USB cables?

Thank you.
 

Holmz

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On the other hand you also risk creating another loop - source to destination and back to source (through additional wire). You would ideally want to twist the interconnect together with the additional ground wire to minimise this.
Once the OP has it connected to the NUX they can starch it against any other peice they want to see/hear if some magic happens to make it better or worse.
then…
maybe…
They do a permanent thing… (Like you suggest)
 

Sokel

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Once the OP has it connected to the NUX they can starch it against any other peice they want to see/hear if some magic happens to make it better or worse.
then…
maybe…
They do a permanent thing… (Like you suggest)
Poor NUC has no way to reject it's noise,it's not grounded,shouldn't a short path to ground fix stuff?
 
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fabiospark

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I did some other testing.

I connected the NUC chassis with the shield of the USB cable that runs from NUC to Interface [no change, RF noise still present]
I connected the NUC chassis to the interface chassis [no change]
I connected the interface chassis and the NUC chassis with the Rotel chassis [no change]

I will try to run a balanced cable from the interface to the Rotel, putting in between, near the Rotel, a Mackie analog mixer that can get balanced inputs and has both bal and unbal outputs.
 

antcollinet

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Why do you have both the PC and the Rotel connected to the HP amp?
Did you say the PC is NOT grounded?

What happens if you disconnect the PC from the HP Amp, and just listen via the rotel? In other words, so the ONLY connection to the PC is the USB.
 

Sokel

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I'll have a look at that because I don't know if the NUC can operate while open.
Don't need to be open,just touch it with the wire from the outside while you hear the noise.
 
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fabiospark

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Why do you have both the PC and the Rotel connected to the HP amp?
If you intend the Desk PC, PC to HP directly it's because with the HPs I can listen to the PC output with no need to switch on the Rotel; and Rotel to HP it's because that let's me listen to the all the other sources that goes to the Rotel, NUC included. One output of the Rotel goes to a Rotel RMB 1075 power amplifier that drives the hi-fi floor loudspeakers.
Did you say the PC is NOT grounded?
If you intend the NUC, yes I think it is not, as it is powered with a brick PS with a two poes plug.
What happens if you disconnect the PC from the HP Amp, and just listen via the rotel? In other words, so the ONLY connection to the PC is the USB.
Sorry but I don't understand this question.

To try to give you a better understang of my setup here's a "map":

Scan 386.jpg

My first goal is to be able to listen to the NUC via my headphones when I'm mixing at the desk PC, controlling the NUC with Remote desktop,
and the second goal is to be able to listen to the NUC through the room loudpeakers. Both goals with no noise, RFI/EMI or HUMs.

As a workaround, for the first goal I will try & use the "send sounds to the host" Desktop restore function, to see if there will be no quality degradation and no latency.
For the second I will try to use balanced cables from NUC to Rotel + a conveter.

But I can't think there's no way to track the source down and to tame it. Nobody have to use balanced cable in a house, haven't they?
f.
 

Timcognito

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antcollinet

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If you intend the Desk PC, PC to HP directly it's because with the HPs I can listen to the PC output with no need to switch on the Rotel; and Rotel to HP it's because that let's me listen to the all the other sources that goes to the Rotel, NUC included. One output of the Rotel goes to a Rotel RMB 1075 power amplifier that drives the hi-fi floor loudspeakers.

If you intend the NUC, yes I think it is not, as it is powered with a brick PS with a two poes plug.

Sorry but I don't understand this question.

To try to give you a better understang of my setup here's a "map":

View attachment 248415
My first goal is to be able to listen to the NUC via my headphones when I'm mixing at the desk PC, controlling the NUC with Remote desktop,
and the second goal is to be able to listen to the NUC through the room loudpeakers. Both goals with no noise, RFI/EMI or HUMs.

As a workaround, for the first goal I will try & use the "send sounds to the host" Desktop restore function, to see if there will be no quality degradation and no latency.
For the second I will try to use balanced cables from NUC to Rotel + a conveter.

But I can't think there's no way to track the source down and to tame it. Nobody have to use balanced cable in a house, haven't they?
f.
They do when they have long cables as you have. Unbalanced cables typically worked fine in a traditional all analogue HIFI stack where all the devices were close together and cables only needed to be 1ft length.

You've brought two PC's into the mix which are great sources of magnetic fields (expecially from graphics hardware, and monitor cabling) to couple into any ground loops you have set up. Further more, you've got your devices separated to an extent where you need 6m and 12m of cabling to join everything up. These long cables both allow large loop areas for better magnetic coupling, and allow large voltage drops from the induced currents through the long cables. Finally you've created complex wiring with multiple ground loops. It is not even slightly surprising you are having problems.

Start with max simplification - one single cable path from nuc to HP amp.

Nuc to Interface to Rotel To HP amp. EVERYTHING ELSE COMPLETELY DISCONNECTED FROM THE SYSTEM. If the Nuc has a monitor, disconnect it and switch it off. Control Nuc from remote desktop - ideally via wifi (No ethernet cables to Nuc)

Do you get noise?

(Do you have ethernet cables anywhere by the way? If so, screened or unscreened)


EDIT - and do you have toslink out of the Nuc, or any device which can take USB in and Toslink out - to give an optical connection to the interface.

EDIT SOME MORE - PS - what are the "zones" box and media box in your original diagram?
 
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Holmz

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If headphones on the focusrite sound OK, then a jensen ISOMAX or similar device onthe last page could be what you need.
You could have two of the Chinese jobs clown earlier, and 10M of XLR between them, with 1M on each end.
 
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