Buzzing through speakers when meeting starts

The fact that:

• The buzzing only happens when a Zoom meeting starts (not just when the app is open)

• The buzzing is not heard by participants

• You've already tried new cables, a sound card, driver updates, Zoom audio settings

• And it happens even when the PC volume is at zero

…strongly suggests this is electrical interference or grounding-related, triggered by Zoom activating certain audio hardware functions during a live meeting (like audio processing, mic activation, or echo cancellation).

When a Zoom meeting starts, it activates:

• Live mic input & speaker output

• Audio processing subsystems (echo cancellation, AGC, noise suppression)

• Possibly WASAPI or ASIO audio drivers, depending on your sound setup

These can introduce high-frequency electrical noise — and if your signal path to the mixer isn't properly isolated, it can result in a ground loop hum or buzzing that's not carried digitally (so Zoom participants never hear it), but does feed into analog output lines and speakers.

Try disabling Zoom’s audio processing features

• Go to Zoom Settings → Audio

• Click "Advanced"

• Try toggling or disabling:

  • "Enable audio enhancements"

  • Echo cancellation

Check power isolation

Try:

• Running the PC and mixer from the same power strip (to ensure same ground)

• Or, better yet, use a power conditioner (like Furman) for your audio rack

Test with another PC

If a laptop (on battery only) doesn't cause the buzz, that confirms the issue is with your PC’s grounding or audio subsystem and not Zoom itself.