Hercules DJCONTROL INPULSE T7 Manual page 58

When you enable stems in a track for the first time,
the separation is not always immediate. This may take
a few moments, while the DJ software analyzes the
track and generates the different parts (vocals,
melody, bass, drums).
You should remember to leave enough time between
the moment when you are separating the stems and
the moment when you are playing them. Once the
different parts for the stems have been generated, the
playback of the stems is instantaneous.
A powerful computer is required in order to use Stems
mode.
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