First Movement: Allegro
The opening orchestral ritornello is joyful and light, and soon transforms into a flurry of sixteenth notes in descending sequence, played by the violins and flutes while the lower instruments drive the piece forward. After the medial caesura, the strings begin a series of canons before the first closing theme, featuring dueling violin I's and violin II's, enters. The second closing theme is much more subtle until the fanfare of its final 2 bars. As the soloist enters, the clarinet repeats the opening theme with the expected added ornamentation. As the orchestra restates the main theme, the clarinet traverses the whole range of the instrument with several flourishes. The secondary theme begins in the parallel minor, and eventually tonicizes C Major before arriving in E Major, the dominant. At the end of the E Major section there is a short pause, where the soloist conventionally improvises a short eingang (cadenza), although no context is offered for a true cadenza.
The canonic material of the opening ritornello returns, this time involving the clarinet, and leads to the novel feature of the soloist accompanying the orchestra with an Alberti bass over the first closing theme. The orchestral ritornello returns, ending with the second closing theme.
The development section explores a few new key areas including F-sharp Minor and D Major, and even has some hints of the Baroque. Before the formal orchestral ritornello leading into the recapitulation, Mozart writes a series of descending sequences with the cellos and bassoons holding suspensions over staccato strings.
As is conventional in Classical concerto form, in the recapitulation the soloist and orchestra are united, and the secondary theme is altered to stay in the tonic. As the secondary theme comes to a close, the clarinet has another chance to improvise briefly, and this time leads the canonic material that follows. The Alberti bass and arpeggios over diminished chords for the soloist recur before the movement ends in a cheerful final orchestral ritornello.
The soloist exposition of this movement appears on almost every professional orchestral clarinet audition.
- Orchestral ritornello: bars 1–56
- Solo exposition: bars 57–154
- Ritornello: bars 154–171
- Development: bars 172–227
- Ritornello: bars 227–250
- Recapitulation: bars 251–343
- Ritornello: bars 343–359
Read more about this topic: Clarinet Concerto (Mozart)