Part 8: Add the seventh, one ingredient at a time · Lesson 072 / 117
Build seventh chords inside C major
Add one more alternate scale note to each diatonic triad.
You built triads by taking alternate scale notes. Continue one more step to add a seventh. In C major the seventh-chord family is Cmaj7, Dm7, Em7, Fmaj7, G7, Am7 and Bm7b5.
Inspect Dm7 = D–F–A–C and G7 = G–B–D–F. Both come entirely from C major, but their thirds differ relative to their own roots. Dm7 has a minor third; G7 has a major third. Both have minor sevenths above their respective roots.
Bm7b5 contains B–D–F–A. It is a diminished triad plus a minor seventh, often called half-diminished seventh. You need to recognise its construction here; a difficult grip is not the learning goal.
Build two examples slowly rather than memorising seven diagrams. The note source is shared, while each root makes a different set of internal relationships.
Hear it
Diatonic Sevenths
Audio fileFour-beat count-in · 60 BPM · Warm sampled electric guitar. Listen once before playing along.
A concrete example
Cmaj7=C E G B; Dm7=D F A C; Em7=E G B D; Fmaj7=F A C E; G7=G B D F; Am7=A C E G; Bm7b5=B D F A.
Try it, slowly
- Derive Dm7 from the scale.
- Derive G7 and compare its third.
- Choose one other family member and verify its four note names.
Check one idea
Why is G7 not Gmaj7 when built from C-major notes?
Show the explanation
The available seventh above G is F, a minor seventh. Gmaj7 would require F#, which is not in C major.
A good place to stop
You can derive and explain two diatonic seventh chords from their actual notes.
Return to the example after a short break. A clear explanation matters more than speed.