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Old 11-02-2020, 04:06 PM   #1
CrashAlpha
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Default Laptop intermittent electrical noise picked up by analog audio

My Dell Laptop XP intermittently generates electrical noise that my analog outboard audio gear is picking up. Even with all USB cables disconnected so therefore peripherals including the connection to the audio interface, and running on batteries - so now power connection or ground-loop issues - the only time the noise NEVER happens is when the laptop is powered down.

It's an SSD drive so I suppose it's possible that read/write could cause that but I tried some disk activity stuff with a disk cleanup while the noise wasn't occurring, but it didn't make it appear. When it does occur, moving the mouse around frantically on the screen seems to stop it - suggesting that I am interrupting something - and returns when I stop.

Anyone heard of this problem?
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Old 11-03-2020, 04:36 AM   #2
Allybye
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Seems odd with no connections between PC and interface so as you conclude probably not a power cable/ground loop issue involving your pc (it might be a loop elsewhere!) In fact I have found that interference is usually less likely when disconnected from the mains and pc running on batteries, and that is not a surprise!
You do not say what all your equipment is or how/where it is connected so I suggest a few basic actions.

From what you describe it sounds like electromagnetic interference transmitted akin to radio waves. It can come from high frequencies (aliased) or from low frequencies too.

Is your equipment in close proximity (unit, cables etc.) and if so try more separation.
I presume you hear the noise through headset or speakers from your interface monitoring point. Is it affected by source selection of gain control? If so ensure balanced cables/inputs are used for mics and high impedance circuits kept physically well away from pc.
If you have a meter check all ground and shield connections for continuity to ensure integrity I.e. to ensure full screening and ensure they are connected to a single star point (i.e a single ground).
Do ensure that you get no interference when the pc is off for a longish period.
Does it use a WiFi or Bluetooth connection and if so try with all that equipment disabled/powered off.

As it is intermittent it may take some time to complete all the tests.
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Old 11-03-2020, 04:56 AM   #3
bFooz
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I'm no expert in this area. What I sometimes do that helps with grounding issues is I tie one end of some wire around a connector or any metal part of the soundcard and the other end around the ground pin in the electrical socket (european, https://www.worldstandards.eu/electr...and-sockets/e/).
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