Stop 6 of 6
Reharmonisation and modulation
Dressing a melody anew and travelling between keys.
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Stop 6 of 6
Dressing a melody anew and travelling between keys.
You've gathered every tool in the observatory: secondary dominants, borrowed chords, tensions, substitutions and altered scales. Now it's time to use them with a purpose. means dressing a melody anew without changing a single note, and means taking the music from one key to another. They are the two skills arrangers use most, and both rest on the same question: which notes do the chords share?
This is the melody you'll work with: eight original bars in C major, harmonised with the most basic chords possible. Listen and play it (it's written for guitar, an octave above how it sounds).
It works, but it's a bit flat: three major chords and a ii. You'll give it depth in three steps, adding one tool at each.
Before changing a single chord, look at which note the melody sings at that moment. Every new chord must contain that note as a chord tone (1, 3, 5, 7) or as an available tension (9, 11, 13 or an alteration that fits). For example, the long E in bar 4 accepts many outfits:
| Chord | Role of E | Does it work? |
|---|---|---|
| C, Cmaj7 | 3 | yes, the original |
| Am7 | 5 | yes |
| Em7 | 1 | yes |
| A7 | 5 | yes, and it sets up Dm |
| Fmaj7 | 7 | yes |
| G13 | 13 | yes |
| Fm | — (E against F and A♭) | no: it clashes |
Look for chords that could have their own dominant, and check the melody:
Now the fine detail:
Compare version 3 with the original: the melody is identical, but now it has a moving bass, shimmering tensions and a moment of shade in bar 3.
In bar 6 you could try Dm7 – D♭7. The melody in the second half (E, D) would be the #9 and b9 of D♭7: two altered tensions in a row. It's legitimate, but very tense for such a simple melody. Reharmonising isn't about using every tool; it's about choosing the one that best tells the melody's story. Play both options and decide for yourself.
When A7 leads to Dm for a moment, that's tonicisation. When the music settles on a new centre, with cadences that confirm it and a new implied key signature, you have modulated. Clues for recognising it by ear:
Listen to this melody. It starts in C and ends in G: when the F♯ appears, home moves.
Compare these two backings. Both use A7 → Dm, but in the first one Dm is a brief stop and the music returns straight to C. In the second, the cadence towards Dm repeats and C never comes back: D minor becomes the new home.
Look at the Roman numerals in the second one: from bar three it's no longer analysed in C but in D minor (i, iiø, iv, V7). When you analyse a piece, that's the moment to switch keys in your analysis: when the chords are better explained from the new centre than from the old one.
The smoothest way uses a , which belongs to both keys. C and G share four chords; Am is the most useful, because it's vi in C and ii in G, and the ii naturally sets up the V of the new key.
Sometimes there's no bridge: the music jumps to the new key at the start of a phrase. Moving up a half or whole step for a song's last chorus is a typical case. It works because the jump lands at a clear point in the form.
A secondary dominant can be the door to a modulation if, instead of going back, you confirm the new centre with more cadences. C7, which could be a simple V/IV, becomes here the V of the new key of F:
The most mysterious: a single shared note is held while the harmony leaps to a distant key. from C to A♭ works because C is the root of the first chord and the third of the second.
Goal: Play the melody over the three versions and create an eight-bar fourth version of your own in which every chord contains the melody note.
Goal: Improvise over the pivot modulation, changing scale exactly in the D7 bar and landing on G.
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