Basic (Diatonic) Modulation
This tutorial shows you how to use the smoothest form of modulation: diatonic modulation.
Modulation means to change key, it occurs sometimes within a song, and often when you want to play two songs together without stopping. You could simply stop playing in one key and start playing in a different key. This works between songs, but you can hear the 'jump'. Often you want to move smoothly between two keys with a less noticeable dividing line.
The modulation chart on the key pages, gives a list of chords to take you between any pair of keys. The diagram above shows the sequence to take you smoothly from A to D. You can simply play this sequence when you need to change key to D.
Understanding the colors
The chords are color coded to give you an idea of what you're doing as you modulate.
- You start out in grey in the key of A. Chords in grey represent chords that are in the starting key.
- The Bm chord is in yellow. Yellow chords are chords that exist in both the starting and ending keys. Bm is in the key of D and the key of A.
- The Em chord is in orange. Orange chords are in the ending key, but not in the starting key. When you leave the yellow chord and enter the orange chords, you've finished changing key.
- The A7 chord is the dominant chord of the new key. It helps establish the new key, so we use it in each modulation.
- The dominant naturally leads into the root chord of the new key, in this case D.
Why this works
Remember in the chord voicing tutorials we talked about pivoting? To keep a smooth progression, you keep as many notes the same between chords.
The same principle is at work here. To move between two keys you use a chord that is in both keys: called a pivot chord. So there is no join, no moment when you change key. This is called a diatonic modulation: the 'change over' chord is valid in both keys, it is marked in green on the modulation chart.
You can't always modulate diatonically. There are no shared chords that can be used to pivot between the keys of A major and C major. The principle is still the same, we keep as many notes as possible during the handover: we use a major / minor modulation.