Relative and Parallel Minor Keys
Choose a major key and see its relative minor, which keeps the same key signature, and its parallel minor, which keeps the same tonic but changes the signature.
Relativa / Paralela
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Relative and parallel minor keys
The relative minor sits 3 semitones below the major and uses the same key signature, so the notes are identical and only the tonic changes. C major pairs with A minor; G major pairs with E minor. The parallel minor keeps the tonic but switches the signature, which is why C major turns into C minor with its three flats. Take C major again. Its relative is A minor, with no sharps or flats, while the parallel is C minor (Eb, Ab, Bb). Modal mixture, also called modal interchange, pulls chords across from the parallel. You hear it in "Stand By Me" and in plenty of pop ballads, where it adds a bit of colour.
Applications
It comes up in songwriting and harmonic analysis, in functional harmony, in key modulation, and when you sit down with repertoire that ranges from the Beatles, who lean on modal mixture a lot, to Bossa Nova (Tom Jobim, Chico Buarque). Handy too when you need to transpose, improvise, or dig up fresh chord substitutions over a progression you already know.
FAQ
Relative or parallel — which sounds "sadder"? Usually the parallel. Keeping the same tonic but dropping to a minor third feels darker. The relative reuses the same notes, so the shift in mood is much gentler.
Do they share chords? The relative shares every diatonic chord, since it's the same scale. With the parallel you only get the tonic name in common, not the quality of the chord.
What is modal mixture? It's borrowing chords from the parallel key, say iv or bVI inside a major key, to enrich the harmony while the tonic stays put.
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