Volume III · Chapter 23
Chromatic Pivot Chords
MUSIC 21A · C-ID MUS 140Chapter quiz →
In the musicianship bookChapter 27: Distant Keys
Introduction: Reaching Distant Keys
In Chapter 18, every modulation went to a closely related key, where plenty of diatonic chords are shared. But Romantic composers wanted more: a sudden shift from C major to A♭ major, or from C to E. Those keys share few or no diatonic triads with the home key. To get there smoothly, composers use chromatic pivot chords: chords that are chromatic in one key and diatonic in the other.
This chapter covers the two most common methods, mixture pivots and common-tone modulation, and introduces the chromatic mediant relationships they make possible. (Chapter 24 adds the third method: enharmonic reinterpretation.)
Click any example to hear it.
Mixture Chords as Pivots
Modal mixture (Chapter 20) gives a major key a second set of chords, borrowed from its parallel minor. Each borrowed chord is diatonic in some other key, so it can serve as a pivot. In C major, the borrowed chords iv, ♭III, ♭VI, and ♭VII open the door to the flat-side keys:
| Destination | Mixture pivots from C major |
|---|---|
| A♭ major | C minor (C: i = iii), F minor (C: iv = vi), E♭ major (C: ♭III = V), A♭ major (C: ♭VI = I) |
| E♭ major | C minor (C: i = vi), F minor (C: iv = ii), G minor (C: v = iii), E♭ major (C: ♭III = I), A♭ major (C: ♭VI = IV), B♭ major (C: ♭VII = V) |
| f minor | F minor (C: iv = i), E♭ major (C: ♭III = VII), A♭ major (C: ♭VI = III) |
| c minor | C minor (C: i = i), F minor (C: iv = iv), E♭ major (C: ♭III = III), A♭ major (C: ♭VI = VI), B♭ major (C: ♭VII = VII) |
| B♭ major | C minor (C: i = ii), G minor (C: v = vi), E♭ major (C: ♭III = IV), B♭ major (C: ♭VII = I) |
Chromatic Mediants
Notice where these modulations went: from C to A♭ and to E♭. Keys (or chords) whose roots are a third apart and that share one common tone (rather than the usual two) are called chromatic mediants. From C major they are:
| Up a third | Down a third |
|---|---|
| E major (common tone E) | A major (common tone E) |
| E♭ major (common tone G) | A♭ major (common tone C) |
The jump to a chromatic mediant is one of the most striking colors in Romantic music (Schubert loved it) and in film scores, where it often signals wonder, magic, or a sudden change of scene. Volume IV returns to these relationships in detail.
Common-Tone Modulation
Sometimes no chord is shared at all. Instead, a single tone is held (or repeated) while the harmony shifts around it to the new key. This is common-tone modulation. It usually happens at a phrase boundary, and the common tone is often in the soprano, where it acts like a spotlight carried from one key into the next.
Analyzing Chromatic Modulations
- Find the destination key from the cadence, as always.
- Look for a chord that is diatonic in the new key and borrowed (mixture) in the old key. Label it on two lines: ♭VI in C = IV in E♭.
- If no chord fits, look for a held common tone between the last chord of the old key and the first chord of the new key.
- If neither works, and especially if a diminished seventh or German sixth is involved, suspect an enharmonic modulation (Chapter 24).
Try It: Chromatic Pivot Finder
Chromatic Pivot Finder
Choose a home key and a distant destination. You'll see which triads the home key (including its borrowed chords) shares with the destination, and hear a modulation by mixture pivot or by common tone.
Summary
- Distant keys share few diatonic chords, so modulations to them use chromatic pivots.
- Mixture pivots: a borrowed chord in the old key (iv, ♭III, ♭VI, ♭VII) is diatonic in the new one.
- Common-tone modulation: one tone is held while the harmony shifts, often to a chromatic mediant key.
- Chromatic mediants are keys or chords a third apart that share one common tone (C–E, C–A♭, C–E♭, C–A).
- When neither method fits, look for an enharmonic pivot (Chapter 24).
Check Your Understanding
Part B: Common-Tone Piece (piano)