The concerto cadenza

In a Mozart concerto, near the end of a movement, the orchestra stops on a suspended chord marked with a fermata. The soloist is alone: this is the cadenza, a moment of improvisation (or prepared improvisation) in which they comment on the themes, show off their virtuosity, then hand back to the orchestra with a trill. Mozart and Beethoven sometimes wrote out their cadenzas, but the spirit remained that of improvisation.

The harmonic architecture

A classical cadenza is one gigantic, prolonged cadential six-four chord:

1. Starting point: the orchestra stops on C/G (C major with G in the bass, the "cadential 6/4"). Harmonically it is a disguised dominant.
2. The journey: the soloist explores, modulates, quotes the themes, strings together virtuoso passages. They can wander, but they know they have to come back.
3. The return: arrival on the dominant chord (G7), often with a trill on the 2nd degree (D) or on the third of the dominant.
4. The resolution: the trill ends, the orchestra comes back in on the tonic chord.

M:4/4
L:1/8
Q:1/4=80
K:C
%%staves {RH LH}
V:RH clef=treble
V:LH clef=bass
[V:RH] !fermata![ceg]8 | g a b c' d' c' b a | g f e d c B A G | !trill!d6 c d | c8 |]
[V:LH] !fermata![G,,G,]8 | z8 | z8 | [G,,F,B,]8 | [C,,C,]8 |]

This five-bar skeleton contains it all: the 6/4 with a fermata, a scale rising and falling (the "journey" in miniature), the trill on D over G7, and the resolution on C.

Ingredients of the journey

• Quote a theme from the movement, then fragment it: keep only its first three notes and move them up in sequence.
• Change mode: replaying a major theme in minor creates a dramatic surprise.
• Virtuoso passages: scales, broken arpeggios, octaves. They act as transitions between quotations.
• Silences and fermatas: the audience holds its breath; a good cadenza player toys with expectation.
• The dominant pedal: a long stretch over a G in the bass prepares the return.

M:4/4
L:1/8
Q:1/4=88
K:C
"C/G" e d c e g f e g | a g f a b a g b | c'2 g2 e2 c2 |]

Above, a three-note cell (E D C, descending) is carried up in sequence: on G, then A, then B. It is the simplest engine to "move a cadenza forward".

Exercise: a 30-second cadenza

Start the ballad track in C and play a few rounds of your minuet (lesson partimento) or of a simple theme. Then stop the track and play the cadenza alone.

1. Open on the C/G chord, fortissimo, with a fermata. Let it ring.
2. Quote the first two bars of your theme, then repeat them a third higher.
3. Fragment: keep three notes and move them up in sequence, getting faster.
4. Virtuosity: a scale or broken arpeggio spanning two octaves, up to a climax.
5. Return: come down, slow down, settle on the G7 chord and trill on D. End the trill with C-D then C, and restart the track.