Recap
The subV7 of a dominant is the dominant seventh chord a tritone away: it shares the third and seventh (swapped). G7 (B–F) ↔ Db7 (F–Cb). This card extends the principle to all dominants and to the related ii chords.
subV of all the secondary dominants (C major)
| Target | Secondary V7 | subV7 |
|---|---|---|
| Dm7 | A7 | Eb7 |
| Em7 | B7 | F7 |
| Fmaj7 | C7 | Gb7 |
| G7 | D7 | Ab7 |
| Am7 | E7 | Bb7 |
| Cmaj7 | G7 | Db7 |
The bass always arrives a half step above the target.
The four ii–V combinations
| Type | Chords toward C | Bass |
|---|---|---|
| ii – V | Dm7 – G7 | D – G – C |
| ii – subV | Dm7 – Db7 | D – Db – C (chromatic) |
| subii – subV | Abm7 – Db7 | Ab – Db – C |
| subii – V | Abm7 – G7 | Ab – G – C |
The subii – subV form (Abm7 – Db7) is the "tritone ii–V": it is exactly what closes Satin Doll (| Am7 D7 | Abm7 Db7 | Cmaj7 |).
Chains of dominants
- Chain by fifths: E7 – A7 – D7 – G7 – C
- Alternating subV: E7 – Eb7 – D7 – Db7 – C: descending chromatic bass, guide tones unchanged.
- All subV: Bb7 – Eb7 – Ab7 – Db7 – C: the chain is by fifths again, but a tritone higher.
- With the ii chords: Em7 A7 | Ebm7 Ab7 | Dm7 G7 | Dbm7 Gb7 | Cmaj7 (descending chromatic ii–Vs).
Tritone substitutions of non-dominant chords
- Final tonic: closing on Dbmaj7 or Gbmaj7#11 instead of Cmaj7 is a surprise effect (used at the end of a standard, a "suspended ending"). It is not a true functional substitution, but an extension of the idea.
- Tritone ii: Dm7 → Abm7 (subii). It works above all when the melody contains common tones (Cb = B, Eb, Gb).
Scales
- On the subV7 the natural scale is Lydian dominant (Db Eb F G Ab Bb Cb): its notes coincide with the altered scale of G (G Ab Bb Cb Db Eb F). Playing Db Lydian dominant over Db7 is equivalent to playing G altered over the original dominant.
- On the subii (Abm7) use Ab Dorian.
Melody and compatibility
- Melody G over Db7 = #11 ✓ (Lydian color).
- Melody D over Db7 = maj7: clash with Cb ✗ (avoid or turn into a passing note).
- Melody C over Db7 = major seventh against the minor seventh Cb ✗.
- Melody A over Db7 = #5: acceptable only with an altered voicing (Db7#5). Remember that the root Db corresponds to the b5 of G7 and the fifth Ab to its b9.
Real example
The Girl from Ipanema (Jobim, F): Fmaj7 – G7 – Gm7 – Gb7 – Fmaj7. Gb7 is the subV of C7: bass G – Gb – F.
Exercise
- Take a turnaround | Cmaj7 A7 | Dm7 G7 |.
- Write all the combinations: | Cmaj7 Eb7 | Dm7 Db7 |, | Cmaj7 Eb7 | Abm7 Db7 |, | Em7 Eb7 | Dm7 Db7 |.
- In the second version check that the bass descends C – Eb – D – Db – C and listen to the chromatic "walking" effect.
Related topics
Tritone substitution (basic card), related ii–V, chromatic substitution and approach chords, augmented sixth chords (the German is a subV), chord-scale theory.