Reading the map
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Chord families
- Tonic (I, iii, vi) — home and home-substitutes
- Subdominant (ii, IV) — the “away” chords that set up the dominant
- Dominant (V, V7, vii°) — tension that wants to resolve to tonic
- Secondary dominants — V7 of any diatonic chord, used to temporarily tonicize it
- Passing diminished — chromatic bass connectors between diatonic chords
- Borrowed — chords pulled from the parallel minor (iv, bVI, bVII, bIII, bII)
- Tritone substitutions — replace any dominant with the dom7 a tritone away
Arrows
- Strong resolution (V→I, ii→V, secondary dominant→target)
- Functional motion that doesn’t fully resolve
- Chromatic / passing motion
Tap any chord to see its voicings, its role in the current key, and every connection — with a plain-English explanation of why each move works.
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