Guy Stalnaker <jimmyg521@gmail.com> writes:
David and Jerry,
I've been using the "method" shown on that Lilypond doc page for
years. I confirm that it does work for me. I can put
\set midiInstrument = #"<name>"
anywhere in a voice and LP will change the midi instrument. Which is
why I suggested it to Jerry.
\set midiInstrument = ... is the same as \set Bottom.midiInstrument = ...
and in the normal Staff, Bottom will be a Voice context in general. So
the change in midiInstrument is only visible within a Voice and moving
the Staff_performer to Voice level lets it see that change.
But that is putting the cart before the horse. If you want to change
the instrument used by the Staff_performer at, well, Staff level, using
\set Staff.midiInstrument = ... is the right choice. Moving the
Staff_performer has its uses (and the example in the manual shows
exactly one such use that may be common in a partitura, namely different
_simultaneous_ instruments in a Staff), but doing it just to avoid
setting midiInstrument at Staff level is rather strange and will have
additional effects not all of which may be desirable.