Rondo-Sonata

A composite form is possible with Rondo and Sonata Form combined in which the contrasting sections function like the corresponding sections of the Sonata-Allegro form. What distinguishes these two forms is the extra repeats of the theme or A section in the original key. Several of the last movements of piano concerti by Mozart and Beethoven have this form.

A very good example if the Rondo of Beethoven's First Piano Concerto. The theme in C-major (Section A ) is introduced by the soloist, repeated by the orchestra ( reverse of a riternello ). The first episode (Section B ) is a transition and second key subject in the expected dominant key of G-major, albeit with a deceptive repeat of it in E-Flat, followed by expected closing material in the expected key of G including the speculative excursion to C-Minor and then G Flat Ninth (V -Flat 9) which becomes a cadence to repeat the theme (A). It is this repeat that makes the form a rondo. It Could have been just the repeat of the exposition of the sonata-form but the episode that follows cinches the issue. The A-minor passage (C) is a little rollicking dance tune that is repeated once. A return of the material of the cadence that ended the opening episode returns but it is wrenched into a circle of fifths modulation that ends at a strong arrival at G7 (V7) and a repeat of the theme (A). This is followed by a rhyme with section B constructed so that rhyme of the second key subject is transposed around to C major. This makes a section B' which is in effect a false transition and rhyme of the second key as in a Sonata form. This includes the deceptive statement of this theme restated in the expected transposition from E-flat to A-flat. There is no completed rhyme with the credential material, instead there is a short coda with the expected soloist cadenza but with a new theme for the closing. This device is used reasonably often in concerti. The scheme is then:

A B A C A B' D

It could be argued that the theme in the coda comes from C . B and B' correspond to transition, second key and close and their rhyme after recapitulation of A. C functions like the development section with cadence using the point furthest removed, harmonically, at A minor and the common device of a circle of fifths modulation back to the dominant and a big cadence to the recapitulation.

Composers like to play with the listeners' perceptions by putting extra repeats of the theme in the development section of a sonata-form, sometimes even right at the beginning so the listener with poor tonal memory will think that he is getting a repeat of the exposition. Sometimes the deception is that the recapitulation is occurring. The tip-off is usually that the key is wrong and there are other signs in a pared-down orchestration or a false modulation at the end of the restatement. Texture, dynamics, and key all cue the points of arrival that define the form.