More Chromatic Color: Pedals, Passing Chords and Mediants

The idea

Borrowed chords and secondary dominants cover most of what you hear in songs. These five devices cover most of the rest.

1. Pedal point. One note holds, usually in the bass, while the chords above it change. The harmony moves and the ground does not, which creates tension and width at once.

• Rock: D – C/D – G/D. Three chords over a constant D.
• Metal: the open low E chugs while power chords or single notes move above it. Every “pedal tone riff” is this device.
• An inverted pedal holds a high note while the chords change below. The Edge of U2 built a style on it.

2. The line cliché. One voice of a held chord moves by half steps while the rest stays. On A minor: Am – Am(maj7) – Am7 – then D, where the moving voice goes A, G♯, G, F♯. You know it from the introduction of “Stairway to Heaven” and from countless film themes.

3. Diminished passing chords. A diminished 7th chord placed between two chords a whole step apart, a half step above the first: C – C♯dim7 – Dm. It works as a disguised secondary dominant, because C♯dim7 is A7(♭9) without its root. Use it to connect I to ii, or IV to V.

4. Chromatic mediants. Two major chords, or two minor chords, whose roots are a 3rd apart and which share exactly one note: C to E, C to A♭, C to E♭, C to A. They do not belong to one key and they do not resolve. They shift. This is the sound of wonder in film music, and of dread in its minor version (Am to Fm, Am to C♯m).

5. Parallel motion (planing). Take one chord shape and move it without regard for the key. Power chords do this by nature. A riff that moves E5 – G5 – B♭5 – E5 outlines a diminished chord and belongs to no ordinary key, and it sounds exactly right for the style.

On your instrument

Device	Try this on guitar
Pedal point	Let the open D string ring and play D, C and G triads on strings 3-2-1 above it
Inverted pedal	Hold the open B and high E strings and move a two-note shape on strings 3 and 4 underneath
Line cliché	Am (x02210), then lower the A on string 3: fret 2, fret 1, fret 0. That gives Am, Am(maj7) and Am7.
Diminished passing chord	Any dim7 shape repeats every three frets: one shape, four names
Chromatic mediant	Play an E major barre chord, then the same shape four frets higher (A♭) or three frets higher (G)
Planing	Move one power-chord shape along the notes of a riff

A useful fact about dim7 chords. A diminished 7th chord is built of minor 3rds only, so it divides the octave into four equal parts. Any of its four notes can act as the root. That is why the same shape works every three frets, and why it can lead to four different keys.

Worked example

One melody note, four harmonizations. The melody holds the note E.

Harmony under E	E is the…	Mood
C major	3rd	Plain and warm
A minor	5th	Sad
E major	Root	Bright, sudden
A major	5th	Open, lifted

C and A minor are in the key of C. E major and A major are not: they are chromatic mediants of C, and each shares the note E with it.

Play C → E → C, then C → A → C, with E as the top note of every chord. The top note never moves and the world shifts under it. That is a chromatic mediant with a common tone, and it is a complete film cue in two chords.

Exercises

1. Write a 4-bar riff over an open-string pedal (E or D). Above the pedal, use at least three different chords or dyads.
2. Add a diminished passing chord to a progression you have written, between I and ii or between IV and V.
3. Write a slow 8-bar instrumental using only chromatic mediants: four major chords a 3rd apart, each held for two bars. Keep one common note on top where you can.
4. Play the line cliché on A minor and on E minor. Then write a 4-bar verse that uses it.

Common mistakes

• Using these as the main course. They are seasoning. A song made only of chromatic mediants has no home to leave.
• Losing the pedal. A pedal point only works if the held note is clearly audible. On guitar, make sure it rings. In a band, agree on who plays it.