Audio input hum on AMP

Has anyone experience hum on the AMP audio inputs and figured out how to fix? It’s happened a few times, seemingly coming and going randomly, and it makes me nervous that I’ve not understood the cause and fix.

Is it safe to assume you’ve ruled out a ground loop hum?

I suspect that it is a ground loop, just no consistency in what is causing it. I’ve ordered a ground loop isolator for the audio input and will test with that next. In the meantime, I’m keeping the audio with video.

I’ve seen it happen when an hmdi is plugged in too. The camera was powered by a different outlet and it completed the circuit/loop. So if it happens again, unplug other components to see if the hum is removed.

And I will say the roughest experience is trying to route audio for a hybrid event using the house pa when it is transmitted to a locked room via ethernet cable. Anytime I walk into that I bring a hum x for everything that isn’t battery-powered and Radical Stage Bugs for anything that might be run through the mixer. If there is a hum at least they can’t blame me.

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Thanks Joe! I’ll let you know how it goes.

Any progress since 2 days ago? A little more detail in your post might be helpful too.

Where do you observe the hum? In an Atem Mini Pro/Iso recording files? On the HDMI program out? On the USB to Computer connection as a webcam? If you open the Atem Control Software, can you observe the noise floor abnormally high in the fairlight audio tab?

If you mute all inputs, does the observed hum go away? (Proving the hum is generated on the input and not on the output).

Also which inputs do you observe the hum on? HDMI 1-4, or Mic/Audio 1-2? (Assuming you ruled out the hum source being on an output like the USB connection in the above mute all test).

Apologies for the late reply.

The hum was on the audio inputs 1 and 2, both the same and audible of the HDMI program out and streaming output. With the inputs muted the hum went away.

Since posting, the hum has not returned. The solution appears to be running everything, cameras included, from the same power outlet as Joe suggested. I have the ground loop isolators and carry them with me in case.