Thanks @cleary . I monitored midi port output to check and here the results:
# amp 0.1 --> velocity 12
# amp 0.2 --> velocity 25
# amp 0.4 --> velocity 50
# amp 0.7 --> velocity 88
# amp 0.95 --> velocity 120
I also noticed that generated midi code for notes is 1 octave lower.
Ex: a1'min'4 chords contents A0 A1 C1 E1 notes but generated code is A-1 A0 C0 E0, so to get a1'min'4 chords you need to write a2'min'4 in atom editor.