Key changes. When I was learning guitar, no one really explained how these work to me. There are some basic approaches I figured out, such as modulating between keys with shared chords… or just abruptly changing key. But I always liked knowing why something worked, or having a set of rules I could follow. I didn’t have any such rules for writing key changes.
Then my guitar teacher introduced me to a classical pianist called Chopin. He wrote some killer music. One such piece is Prelude No20, from Opus 28.
This prelude is great. There is a lot that can be learned from it. If you haven’t already, check out the other lesson from this prelude. It also has a lot of beautiful key changes, so by analysing the piece, we can learn some approaches used by Chopin for modulating between keys.
We can take the examples and very easily apply it to rock and metal playing. It is possible demonstrate the validity of these rules just by smashing power chords together!
These rules work.
I like to think of them as shortcuts for writing interesting music.
This piece by Chopin has a main theme in the first bar, and each subsequent bar is a variation on that theme, either by changing chords, the key signature, or both.
Bar by Bar Analysis of What Chopin is Doing
I’ve already covered the ways Chopin changes the chords around (mainly by using non-diatonic chords), so let’s look at the key signature changes. I’ll explain what he does and then give you a set of rules you can use in your own music composition:
Bar 1 – We start in the key of C minor
Bar 2 – Chopin modulates up a b6 into a major key. We are now in Ab major.
Bar 3 – Change key back down to C minor
Bar 4 – Up a P5 into a major key. We are now in the key of G major
Bar 5 – Into the parallel minor key – now in the key of G minor
Bar 6 – This one is badass. Chopin moves to G mixolydian b6:
Ao D7b5 G∆ Ao G7
Iio V7b5 I iio I7
The first three chords form a perfect cadence in the key with a chromatically descending bass line via the altered chord. The fourth chord, Ao, re-affirms the key, before creating a half cadence with the I7… which also happens to be the 5th for the next key…
Bar 7 – Back to C minor. V-i cadence.
Bar 8 – C minor again. No key change in this bar.
Rules for Key Changes
So if we take the techniques Chopin uses for changing key and turn them into a simple set of rules that we can use to write key changes in our own music, we get:
Rule 1: Distance of a b6
Minor key – Up a b6 — Major Key
Major key – down a b6 – minor key
Rule 2: Distance of a P5
Minor key – Up a P5 – Major key
Major key – Down a P5 – Minor key
Rule 3: Parallel Keys
When in a minor or major key, you can move to a major or minor key with the same tonic.
Rule 4: Turn the I into I7 to destabilise the key
The title says it all. Use this before changing to a key a P5 lower. You are effectively treating the tonic of the current key, as a secondary dominant for the following key.
Try It Out In Your Playing
If you want a really, really fun way to test this out… and actually hear it in your playing…
- Quickly run over your one string major scale and one string minor scale
- Use power chords along the scale
- Make up some riff in E minor using a one string minor scale
- Move to a riff in C major (Rule 1) on the 5th string
- Change to playing in C minor (Rule 3)
- Change back to C major (Rule 3)
- Back down to E minor
- Up to a riff in B major on the 5th string (Rule 2)
- Back to E minor
- Back up to a riff in C major on the 5th string (Rule 1)
- End your riff on C7 (Rule 4)
- Move to a riff in G major (Rule 4)
Another interesting point is that Chopin gives us a very melodic way to move between keys that are a b2 apart. Moving from C major to B major is pretty jarring. Moving from C major, to E minor, to B major… is pretty nice.
So there you have it, 4 rules for applying key changes into your own songwriting that you can use right now.
Listen to the piece here:
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