Triads, 7th Chords, Lead-sheet Symbols
Dr. B Music Theory
Triad
The most common chords are triad. It's a 3 notes chord.
triad = tertial types/sonorities:
- major triad: (M3 P5) C E G
- augmented triad: (M3 A5) C E G#
- minor triad: (m3 P5) C Eb G
- diminished triad: (m3 d5) C Eb Gb
Lead sheet symbols
- A (+) for augmented
- M for major
- m for minor
- d (°) for diminished
The 1 is called the root, the 3 is called the 3rd and the 5 is called the 5th.
The root of the chord is always write in uppercase letter. For exemple:
- Bb+ is B flat augmented triad.
- Bb is B flat major triad.
- Bb- or Bbm is B flat minor triad.
- Bb° is B flat diminished triad.
Seventh Chord
Using 4 notes. The interval between root and top note is a seven.
- MM7 = Major triad with Major seven / Major seven chord, notation CMA7, CMAJ7, C△7.
- Mm7 = Major triad with Minor seven / Major minor seven chord (dominant 7), notation C7.
- mm7 = Minor triad with Minor seven / Minor seven chord, notation C-7, Cm7.
- dm7 = Diminished triad with Minor seven / Half diminished seven chord (Minor 7b5), notation CØ7, C-7b5.
- dd7 = Diminished triad with Diminished seven / Diminished seven chord (fully diminished), notation C°7.