Recreations of classic instruments like the Mellotron, Fairlight and iMS-20 are favorites around here. Petites Ondes ($3) joins this group as an iPad reproduction of a classical electronic instrument. It’s sort of theremin-esq, however really belongs in a class by itself. The expressive controls work like this: Right hand controls pitch and left hand controls dynamics. Other features include vibrato, trill, timbre select, reverb and pitch. Like a real instrument, expect this one to take some time to master.