Slaving activators to it could change it's pitch.
High signal +1 pitch, Low Signal -1 pitch, Begin at C3 or C4 and allow us to go up and down manually from there.
Slaving it to activator causes it to play it's tone on High signal.
This would require you use one music block per note on your instrument, but would allow full range from C0 up to C8+ on a music box :D
((Personally I would like to see the note sustained for the duration of the High signal also))