by Gary Ewer, from “The Essential Secrets of Songwriting” website.
A few days ago I wrote about ways that you can keep a song from getting stale on the listener, changing key (also known as modulating) being one possible way to achieve this. There are many ways to modulate, and depending on the style of your song, you’ve got opportunities for something smooth or something more startling.
In this post I want t0 focus on modulations that occur by way of “common tone”. This means that between the last chord of the original key, and the first chord of the new key, the key changes, but at least one note exists in both of those chords. Here’s an example of what I mean:
1. “Common Tone Modulation ” from verse to chorus:
A – Bm – A – Bm – D – Bm – F#m – E (opt. repeat)||
Ab – Db/Ab – Ab – Db/Ab – Eb/G – Fm – Db – Eb (repeat)||
Small transition for the end of the chorus to get back to the key of the verse:
Ab – Fm – Ab – E/G# ||
This is a common tone modulation in the sense that the notes Ab and G# are enharmonic equivalents: though they are indicated with different letter names, they sound the same on a guitar or piano.
There are many ways to vary this progression, and it’s only meant to give you an idea of what the possibilities are. For example, holding a pedal tone A through the first four chords of the verse gives a nice motivic connection to the first four chords of the chorus.
The nice thing about this progression is that the chord at the end of the transition moves back into the original key by the same way it left it: a common tone.
Common tone modulations of this type are considered a kind of abrupt modulation, in the sense that the last chord of the original key (despite its common tone with the first chord of the new key) doesn’t exist in the new key. So you may find that you have to finesse it a bit to work in your song, depending on your chord progression.
If you like this type of modulation, simply do this to fit your own progression: End your verse on a V-chord, start the chorus one semitone lower than your original key.
One final point: I have often said that a downward modulation of a semitone (which this is) is really hard to make work. But this one case where it can work, by virtue of the fact that the common tone provides the necessary musical glue.
If you’d like to know more about chords, and get lists of hundreds of progressions you can use right now, Gary Ewer’s songwriting e-books include collections of all sorts of progressions. From simple ones to more complex changes, you’re sure to find progressions you can use in whatever song you’re writing. Click here to find the songwriting e-books.