cycling noise being caused by Broadband modem, help needed..

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Re: cycling noise being caused by Broadband modem, help needed..

Post by merlyn »

blinddrew wrote: Thu Dec 02, 2021 11:36 am But the monitors are Eris 5s, which are type 1 so should be providing an earth for the system?

In a classic ground loop there are two (or more) paths to earth. Take a PC plugged into the wall, and active monitors, also plugged into the wall. There are two paths to earth. Join the two together with an audio connection and the audio connection completes the loop. There is now a loop with a tiny resistance, so a tiny voltage can induce a current.

There have been posts from people with laptops where the problem is the lack of a solid ground. I don't understand why balanced connections don't fix that.

The problem here seems more like a lack of ground problem, because there aren't two paths to ground to make the classic loop, and balanced connections haven't fixed it.

@pax-eterna -- just checking -- the leads from interface to monitors are TRS plugs or XLRs?
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Re: cycling noise being caused by Broadband modem, help needed..

Post by blinddrew »

merlyn wrote: Thu Dec 02, 2021 12:23 pm There have been posts from people with laptops where the problem is the lack of a solid ground. I don't understand why balanced connections don't fix that.

If there's no ground in the system at all then balanced connections won't make any difference?

The problem here seems more like a lack of ground problem, because there aren't two paths to ground to make the classic loop, and balanced connections haven't fixed it.

But we've established that the monitors are grounded, so it shouldn't be a lack of ground problem. Even if just the monitors are grounded you can still create a loop of ground > monitor 1 > interface > monitor 2 > ground.
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Re: cycling noise being caused by Broadband modem, help needed..

Post by merlyn »

blinddrew wrote: Thu Dec 02, 2021 3:02 pm But we've established that the monitors are grounded, so it shouldn't be a lack of ground problem. Even if just the monitors are grounded you can still create a loop of ground > monitor 1 > interface > monitor 2 > ground.

Sure, but what closes the loop is the network cable.
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Re: cycling noise being caused by Broadband modem, help needed..

Post by jjlonbass »

UTP Ethernet cables such as Cat 5, 5e or 6 have nothing that should be connected to earth, so no opportunity for a loop. All signals in such an Ethernet cable are differential (balanced if you like) and are supposed to be transformer isolated at each end.

All of this means that it would be very surprising for an Ethernet connection to be the root cause of this sort of interference.

John
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Re: cycling noise being caused by Broadband modem, help needed..

Post by N i g e l »

jjlonbass wrote: Thu Dec 02, 2021 4:24 pm UTP Ethernet cables such as Cat 5, 5e or 6 have nothing that should be connected to earth, so no opportunity for a loop. All signals in such an Ethernet cable are differential (balanced if you like) and are supposed to be transformer isolated at each end.

All this means that it would be very surprising for an Ethernet connection to be the root cause of this sort of interference.

John

I totally agree. The ethernet chip networks to the outside world via "magnetics" ie a signal transformer.
A LAN cable can be 100m long and needs to operate across different ground domains ie - equipment on different mains sockets or in different buildings using a different phase of the mains & earth.
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Re: cycling noise being caused by Broadband modem, help needed..

Post by blinddrew »

Getting back to the OP, I'd start by stripping the system right back to the essentials then re-introduce one element at a time. Start with just the laptop, interface and headphones, then add one monitor speaker, then the other, then any additional elements (including the network connection) one at time.
Identifying which one is causing the issue should help identify the actual problem.
Also check the clocking. ;)
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Re: cycling noise being caused by Broadband modem, help needed..

Post by merlyn »

blinddrew wrote: Thu Dec 02, 2021 5:14 pm Start with just the laptop, interface and headphones ...

In case the OP wonders which laptop -- it's not a laptop. It's an Intel NUC 8i7 which runs on a laptop-like power supply.

I would think what you've suggested is a good idea.
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Re: cycling noise being caused by Broadband modem, help needed..

Post by blinddrew »

merlyn wrote: Thu Dec 02, 2021 5:40 pm
blinddrew wrote: Thu Dec 02, 2021 5:14 pm Start with just the laptop, interface and headphones ...

In case the OP wonders which laptop -- it's not a laptop. It's an Intel NUC 8i7 which runs on a laptop-like power supply.

My bad! :thumbup:
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Re: cycling noise being caused by Broadband modem, help needed..

Post by ef37a »

https://www.onlogic.com/uk-en/nc100-50/ ... BsEALw_wcB

That NUC has a shielded Ethernet port but I cannot ever remember seeing a shielded port on a modem and I have had about 8! Then, as mentioned, does the PSU pass mains ground? Laptops used to always have shielded port in my experience (and desktops always?) but my Lenovo i7 does not. If an FTP patch cable is not grounded at at least one end it is going to become a super aerial!

Building to building earth currents are I understand a big problem with shielded Ethernet and fibre has replaced much of it?

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