Definition
The solo concerto sets one instrument (or a few) in dialogue with the orchestra. In its Classical form it has three movements: fast – slow – fast. Two formal models are fundamental:
- the ritornello form of the Baroque (Vivaldi, Bach);
- the concerto sonata form of the Classical period (Mozart), which Hepokoski and Darcy call sonata type 5.
Ritornello form (Vivaldi)
The ritornello is an orchestral theme (tutti) made of several segments (for example a–b–c); it returns several times, whole or fragmented, in different keys; between one ritornello and the next the soloist plays virtuosic episodes that modulate.
| Section | Who plays | Key (in a major key) |
|---|---|---|
| R1 | tutti, complete ritornello | I |
| S1 | soloist, modulating episode | I → V |
| R2 | tutti, part of the ritornello | V |
| S2 | soloist | V → vi (or others) |
| R3 | tutti, fragment | vi |
| S3 | soloist | → I |
| R4 | tutti, complete ritornello | I |
In the minor the typical stages are i, III, v, iv (Roman numerals relative to the natural minor).
Example: Vivaldi, “Spring” from The Four Seasons (in Op. 8, Il cimento dell'armonia e dell'inventione, 1725), first movement in E major: the tutti ritornello returns between violin episodes that depict the birds, the stream, the thunderstorm, as explained by the sonnets printed with the score.
Bach takes up the model in the Violin Concertos BWV 1041–1042 and in the Italian Concerto BWV 971 for solo harpsichord, in which the “tutti” and “soli” are rendered with the two manuals.
Concerto sonata form (Mozart)
It is often described as a double exposition:
- Initial orchestral ritornello (R1): presents the main themes while staying in the tonic (or nearly so).
- Solo exposition (S1): the soloist enters, takes up and varies the themes, adds material of its own and modulates to the dominant; it ends with a trill and a cadence, followed by an orchestral ritornello.
- Development (often with virtuosic figures from the soloist).
- Recapitulation (soloist and orchestra together), in the tonic.
- Cadenza: the orchestra stops on a cadential six-four chord (I6/4) with a fermata; the soloist improvises (or plays a written-out cadenza) and closes with a trill on the dominant; the orchestra re-enters with the final ritornello on V7–I.
Examples: Mozart, Piano Concerto No. 21, K. 467 (1785), No. 20 in D minor, K. 466, No. 23, K. 488.
Romantic evolution
- Beethoven, Concerto No. 5 “Emperor,” Op. 73 (1809): the piano enters right away with written-out cadenzas; Beethoven indicates that the final cadenza should not be improvised.
- Mendelssohn, Violin Concerto, Op. 64 (1844): the soloist enters in the second bar, the written-out cadenza comes before the recapitulation (not at the end), and the movements are linked without pauses.
- Tchaikovsky, Piano Concerto No. 1 (1875), Rachmaninoff, No. 2 (1901): the concerto becomes a great symphonic drama.
The second and third movements
- Slow movement: cantabile aria (ternary or variations), sometimes in a closely related key (IV, vi).
- Finale: rondo or sonata-rondo, often with short solo cadenzas before the returns of the refrain.
Application for a producer
Ritornello form is very close to the hook–verse–hook structure of a song: the orchestral ritornello is the instrumental hook, which also returns in reduced form (a 2-bar fragment) between the verses of the “soloist” (the voice or a lead). The soloist's cadenza is the free solo over a pedal or in silence before the whole group re-enters: a break or an “a cappella drop.”
Related
Concerto grosso, Sonata-rondo, Sonata form: Hepokoski and Darcy's Sonata Theory, Cadences (cadential six-four), Bernstein: what is orchestration.