Arturia BeatStep Pro MIDI/Analog Controller and Sequencer Kit with CV/Gate Cables (Black) - Manual (Page 12)

1.1.3. Something to consider: Ground loops
A ground loop is an unwanted current in a conductor connecting two points. The result is
noise in your audio signal, usually in the form of a low-frequency hum. In setups including
computers, interfaces and audio devices, it's possible to end up with an annoying ground
loop. We have provided you with a solution, however: the anti ground loop adapter .
1.1.3.1. When should I use the anti ground loop adapter?
In most cases you will not need the anti ground loop adapter.
If you don't have a ground loop problem in your setup, simply connect the BeatStep Pro with
the supplied USB cable to a computer or a USB power supply.
You should use the included anti ground loop adapter if you experience background noise
in your speakers that disappears when you disconnect the audio interface from your
computer or the CV/Gate connections to your analog gear. A ground loop can also cause
problems with pitch tracking when using the BeatStep Pro CV connections with analog
synthesizers.
Connect the anti ground loop adapter as follows:
7 Arturia - User Manual BeatStep Pro - BeatStep Pro Overview