je vous recopie un article intéressant sur les différents types de substitutions d'accords :
When we talk about reharmonization of a piece we are actually referring to the concept of substituting some of the chords without changing the original idea of the cadence, i.e., if we are going to resolve to a Cmaj7, the substitutions we are making are still going to resolve to Cmaj7; we will simply arrive at the same resolution of the cadence by a different route.
There are four kinds of substitutions:
A - Diatonic Substitution by Tonal Groups
B - Tritone (flat-5) Substitution
C - Flat-3 Substitution
D - Coltrane Cycles
A - Diatonic Substitution by Tonal GroupsDeveloping 4-note chords based on the major scale, we find that some chords have a strong relationship between them.
When we compare the spelling of these chords we can see the notes they share in common and divide them into three tonal groups.
Within these groupings, each chord can be substituted by its partner(s):
B - Tritone SubstitutionThe tritone substitution is a dominant 7th chord whose root is a tritone (flat-5 interval) away from the original dominant 7th chord. The chords are interchangeable because the tritone interval pitches are identical in each. This substitution technique was developed in the bebop period.
C. The Flat-3 SubstitutionThe diminished 7th chord could be seen as a dominant 7th with a flat-9 in the bass; for example: Abdim7 (Ab-B-D-F) is the equivalent of G7#5b9 or G7 altered (G B Eb F) which share the 3rd and the 7th. We can move this dominant chord in minor thirds just as with the diminished chords; the result is the Diminished Cycle:
G7 Bb7 Db7 E7 [enharmonic spelling of F-flat]
Ex.1 Original: Dm7 G7 Cmaj7 Cmaj7
With b3 Subs : Dm7 Bb7 Cmaj7 Cmaj7
Dm7 Db7 Cmaj7 Cmaj7
Dm7 E7 Cmaj7 Cmaj7
We can also add the related ii m7 chord:
Ex.2 Original: Dm7 G7 Cmaj7 Cmaj7
b3 Subs : Fm7 Bb7 Cmaj7 Cmaj7
and the related ii m7 chord:
Abm7 Db7 Cmaj7 Cmaj7
Bm7 E7 Cmaj7 Cmaj7
We get different G7 sounds with each of these dominant substitutions as all of the G7s are altered.
G7...... original
Bb7..... G7#5b9
Db7..... G7b5b9
E7...... G7b9
Pluralities (same chord tones, different roots)
G13 = Dm9 = Fmaj7
Bb13 = Fm9 = Abmaj7
Db13 = Abm9 = Bmaj7
E13 = Bm9 = Dmaj7
The above chords are interchangeable; i.e., you could substitute:
a Dm9 for a G13 or an Fmaj7 or an Fmaj7 for a Dm9 or a G13:
Notewise, the breakdown is as follows:
G13: G B D F E This is a Dm9, 13, or 6 (with G in the bass)
Dm9: D F A C E This is also a G7 9 11 13 (with no root) or an Fmaj7 13
Fmaj7: F A C E This is also a G7 9 11 13 (with no 3rd and no root)
D. Coltrane CyclesIn the 60s, John Coltrane developed a harmonic system based on the "Augmented Cycle"; that is, he used the augmented chord motion of major thirds to create yet another way to substitute within the original cadence.
Based on the augmented triad, we get the following chords:
C E G#
B D# G
A C# F
Bb D F#
The "Giant Steps" Cycle
In addition to the Major 3rd motion between roots of major chords, Coltrane would add the appropriate dominant 7th before each major chord in the augmented cycle.
Augmented Cycle (clockwise):
C / E / G# / C /
The Augmented Cycle with respective dominant 7th chords added:
C B7 / E D#7 / G# G7 / C /
Augmented Cycle (counter-clockwise)- like the original "Giant Steps" progression:
C / G# / E / C /
Augmented Cycle with added Dominant 7 chords:
C D#7 / G# B7 / E G7 / C /
Now let's state the augmented progression in the original "Giant Steps" key of B:
Augmented Cycle: B / Eb / G / B /
And finally, the augmented cycle with Dominant 7th chords added:
B D7 / G Bb7 / Eb F#7 / B /
Another possibility: B Bb7 / Eb D7 / G F#7 / B /
Countdown Cycle
The following cycle is the same as Coltrane's "Giant Steps" cycle but begins on the ii m7 chord of the original tonality.
This composition is based on Miles Davis' "Tune Up" cadence:
Original: Em7 / A7 / D / D /
Countdown Cycle: Em7 F7 / Bb Db7 / Gb A7 / D /
"Giant Steps" Cycle: D F7 / Bb Db7 / Gb A7 / D /