3.2 Harmonic Substitutions
Advanced techniques for varying harmonic progressions
Key Concepts
Triton Substitution
V7 → ♭II7: two dominant chords a tritone apart share the same tritone (3rd and 7th). Chromatic bass movement.
Harmonic Function
Substitutions retain the same function (tonic/subdominant/dominant) but change the colour. The function takes precedence.
Modal Interchange
Forming parallel chords (C major → C minor). IVmaj → IVm and VImaj → VIm are the most common.
Secondary Dominants
Create temporary dominant chords (V7/x) for non-tonic chords. This adds tension and local resolution. Each chord can have its own V7.
Diatonic Substitutions
Diatonic chords with shared notes: I ↔ VIm ↔ IIIm (all contain E and G in the key of C). Relative substitutes.
Reduced Substitutions
Dim7 can replace V7 (they share 3 out of 4 notes). Furthermore, every dim7 has 4 names (symmetry). Very versatile.
What is a harmonic substitution?
A harmonic substitution is the technique of replacing one chord with another that retains a similar harmonic function but adds variety and colour. It is fundamental to modern jazz and reharmonisation.
Triton Substitution
Tritone substitution
Concept: Replace a dominant 7th chord with another dominant 7th chord a tritone apart.
Original
G7
G-B-D-FSubstitute
D♭7
D♭-F-A♭-C♭Dominant Substitutes
For a dominant V7, we can use:
- SubV7: ♭II7 (tritone substitute)
- Diminished 7: VIIdim7, #Idim7, IIIdim7, Vdim7
- Related IIm7: Substitute IIm7
Modal Interchange
Modal Interchange
Choose chords in the parallel minor (or major) key.
In C major, we can use chords from C minor:
- IVm7 instead of IV (Fm7 instead of Fmaj7)
- ♭B♭ maj7 (A♭ maj7)
- ♭VII7 (B♭7)
- ♭IIImaj7 (E♭maj7)
Secondary Dominants
Concept: Creating temporary dominants for chords that are not the tonic.
| Objective | Secondary Dominant | Example in C |
|---|---|---|
| IIm7 | V7/II (A7) | A7 → Dm7 |
| IIIm7 | V7/III (B7) | B7 → Em7 |
| IV | V7/IV (C7) | C7 → Fmaj7 |
| V7 | V7/V (D7) | D7 → G7 |
| VIm7 | V7/VI (E7) | E7 → Am7 |
Chord Quality Substitutions
Sus Chords
Replace V7 with V7sus4
G7 → G7sus4
It creates a delay, then resolves it
Relative Substitutes
Replace with the corresponding major/minor
Am7 ↔ Cmaj7
They have a lot in common
Practical Examples of Substitutions
"Satin Doll" – Tritone Subs
Analysis: Duke Ellington makes extensive use of tritone substitutions. The Dm7–G7 progression becomes Dm7–D♭7, creating chromatic movement in the bass (D→D♭→C).
Substitution: G7 → D♭7 (tritone substitution). The bass moves down chromatically instead of jumping by a fourth.
Listen to Examples"Autumn Leaves" – Modal Interchange
Analysis: The major section (Cmaj7–Fmaj7) is often replaced with Cmaj7–Fm7, taking the IVm from the parallel minor key. This creates a more melancholic tone.
Substitution: Fmaj7 → Fm7 (modal interchange from C minor). Bill Evans used this substitution frequently.
Listen to examples"Fly Me to the Moon" – Secondary Dominants
Analysis: Secondary dominant progression: A7→Dm7→D7→Gm7→C7→Fmaj7. Each chord is preceded by its V7, creating a strong, directional harmonic movement.
Substitution: Add V7/II (A7), V7/IV (C7) and V7/V (D7) before the target chords. This creates a continuous tension→resolution.
Listen to examples"Take the A Train" – Diminished Subs
Analysis: G7 is often substituted with G#dim7 (or Bdim7, Ddim7, Fdim7 – same structure). The diminished chord contains the leading notes of G7 and adds chromaticism.
Substitution: V7 → #Vdim7. This works because dim7 contains the 3rd and 7th of the original V7. Different sound, same function.
Listen to examplesInteractive Audio Examples
Listen to the most common harmonic substitutions. Compare the original with the substitution to hear the difference in tone.
Study Tips
1. Memorise the Common Tones
Substitutions work because they share notes. G7 and D♭7 share B–F (tritone). I and VIm share E–G. Identify these connections to understand why a substitution works.
2. Practise Tritone Subs on II-V-I
Take an II-V-I progression (Dm7-G7-Cmaj7) and replace the V7: Dm7-D♭7-Cmaj7. Play both versions in all 12 keys. Listen to how the character changes, but the function remains the same.
3. Create a table of secondary dominants
For each key, write down all the secondary dominants (V7/II, V7/III, V7/IV...). Practise resolving them to their targets. In C: A7→Dm, B7→Em, C7→F, D7→G, E7→Am.
4. Experiment with Modal Interchange
Take a major progression (I–IV–V–I) and replace it with chords from the parallel minor scale: I–IVm–V–I, or I–♭VII–IV–I. Listen to how the mood changes from ‘bright’ to ‘melancholic’.
5. Analyse the Standards
Choose 10 jazz standards and identify all the substitutions: tritone substitutions, modal interchange, secondary dominants. Transcribe three different versions of the same standard (e.g. ‘Autumn Leaves’ by Bill Evans, Chet Baker and Cannonball Adderley).
6. Use the Circle of Fifths
The circle of fifths illustrates harmonic relationships. Secondary dominants follow the circle in a clockwise direction (A7→D7→G7→C7→F7...). Tritone subs move in the opposite direction.
7. Combine Substitutions
Once you have mastered them individually, combine them: II–V becomes IIm7–SubV7, or, by adding V7/II first: V7/II–IIm7–SubV7–I. This creates layered harmonic complexity.
8. Listen Carefully
Substitutions change the ‘colour’ but not the function. Listen to how the tritone substitution sounds more ‘chromatic’, modal interchange more ‘dark’, and secondary dominants more ‘directional’. Train your ear to recognise these colours.
Common Mistakes
1. Confusing Function and Colour
Problem: Replacing a chord with one that has a completely different function. Example: replacing Imaj7 (tonic) with V7 (dominant) – this is not a substitution, it is a change of function.
Solution: The substitutions preserve the harmonic function: Tonic → Tonic (I ↔ VIm), Dominant → Dominant (V7 ↔ SubV7), Subdominant → Subdominant (IV ↔ IIm). Always respect the harmonic function.
2. Tritone Sub on Non-Dominant Chords
Problem: Applying tritone substitution to m7 or maj7 chords. Example: Dm7 → A♭m7? This doesn’t work because tritone substitution requires the minor 7th of the dominant.
Solution: Tritone substitution works ONLY on dominant chords (X7). If you want to substitute for Dm7, use relative substitutes (Fmaj7) or modal interchange, not tritone substitution.
3. Ignoring the Melodic Context
Problem: Substituting without checking for compatibility with the melody. G7→D♭7 works harmonically, but if the melody contains a ‘D’ (the 5th of G7, but a very dissonant ♭9 of D♭7), it creates a clash.
Solution: Always check the notes in the melody. If the melody contains the 5th of the original chord, a tritone substitution may not work (it becomes a ♭9). Adjust the voicings or choose a different substitution.
4. Abusing Secondary Dominants
Problem: Adding V7/x before every chord. Result: an endless chain of dominant chords that loses the sense of the tonic. It sounds like a continuous, aimless modulation.
Solution: Use secondary dominants strategically. Two or three per section of eight bars is sufficient. Include some simple diatonic movements for contrast and tonal stability.
5. Inappropriate Modal Interchange
Problem: Using modal interchange in places where the piece calls for greater stability. Example: replacing the final Imaj7 with Im7 – this creates ambiguity rather than a sense of conclusion.
Solution: Modal interchange works best with ‘passing’ chords (IV→IVm, VI→♭VI). Keep the I and V chords distinct in final cadences to ensure stability. Use interchange to add colour, not to destabilise the harmony.
6. Don’t Focus on the Result
Problem: Applying substitutions ‘on paper’ without actually playing them. They’re theoretically correct, but they sound awful in the specific context of the piece.
Solution: Always check whether the substitution sounds right in context. If it sounds forced, contrived or ‘wrong’, do not use it, even if it is theoretically correct. Your ear is the final judge, not theory.
Full Summary
Main Types of Substitutions:
- Tritone Substitution: V7 → ♭II7 (they share a tritone and a chromatic bass)
- Modal Interchange: Taking chords from the parallel mode (IV→IVm, VI→♭VI)
- Secondary Dominants: V7/x for every non-tonic chord
- Relative Substitutes: I↔VIm, IV↔IIm (shared notes)
- Diminished: Dim7 replaces V7 (3 notes in common)
Fundamental Principles:
- Substitutions preserve the harmonic function (T/SD/D)
- Common tones explain why a substitution works
- The melody determines which substitutions are possible
- Tritone sub works ONLY on dominant chords (X7)
How to practise:
- Stores common tones between interchangeable chords
- Practise tritone substitutions on II-V-I progressions in all keys
- Create tables of secondary dominants for each key
- Analyses different versions of the same jazz standards
Mistakes to Avoid:
- Do not change the harmonic function (T→D is not a substitution)
- Do not apply a tritone to non-dominant chords
- Do not overuse secondary dominants (2–3 per section)
- Always check that it is compatible with the melody