Arturia KeyStep 37 MIDI Keyboard Controller and Sequencer - Manual (Page 62)

5.4. Adding Notes in other octave ranges
To add notes in other octave ranges simply press the Oct- or Oct+ buttons. This will move
the point where notes are inserted in the arpeggio an octave up or down. Hold Oct- and Oct+
simultaniously to reset the insertion point to the default octave.
Having read section 2.3.6 [p.24] you already know that the Hold button allows you to keep
the arpeggiator running after you take your fingers off the keys.
There's a second use for the Hold button: when Hold mode is active, you can keep adding
notes to an arpeggio as long as you continue holding down at least one key. Again, you can
press the Oct +/- buttons to access other octave ranges of the keyboard and add notes in
that octave range.
You can keep adding notes to the arpeggio for quite a while: the limit is 32 notes.
57 Arturia - User Manual KeyStep 37 - The Arpeggiator