> What is the “len” parameter on the arpeggiator ap ?
It changes the size of the rhythmic pattern. You can use to create irregular rhythmic patterns.
> And I don’t really understand what is the “New “as played” and “chord” modes in the arpeggiator
as played repeats the note in the order in which they were played when you play the chord. For example, if you play a C chord by pressing C-G-E (in that order), the arpeggiator will repeat C-G-E-C-G-E. By rapidly arpeggiating and holding the notes of the chord as you play it, you can control the arpeggio order.
Chord simply plays all the notes of the chord together, at a rhythm defined by the arpeggio rhythmic pattern.
These new features are new in v1.4. Have you upgraded to this version?