Flute 1, Flute 2, Alto Flute 3, Flute 4, Flute 5, Alto Flute 6, Bass Flute 7 The concerto grosso of Corelli's day was often a trio sonata with extra voices used to emphasize various aspects of the music. This piece has can be played as a trio but has also been arranged for 4 C flutes, 2 altos and 1 bass. Alternate parts have been added to use all C flutes as well.