Diminished Seventh Chord Theory Things   William Wieland
  • 3 3 3 ( steps), i.e. all minor 3rds (Keyboard)
  • diminished triad + diminished 7th
    (2 minor 3rds + an augmented 2nd smaller than an octave)
  • Lower 3, 5, & 7 of a V7.
    (G - B - D - F becomes G - B flat - D flat - F flat.)
  • In minor, build a seventh chord on the leading tone: ti - re - fa - le. 
    (a minor: g sharp - b - d - f)
Half-diminished Seventh Chord
  • 3 3 4 ( steps) (Keyboard)
  • diminished triad + minor 7th
    (2 minor 3rds + a major 2nd smaller than an octave)
    (The minor 7th is also used in the V7.)
  • Lower 3 & 5 of a V7.
    (G - B - D - F becomes G - B flat - D flat - F.)
  • In major, build a seventh chord on the leading tone: ti - re - fa - la. 
    (C major: B - D - F - A)
Diminished and Half-diminished Seventh Chord Quiz
Diminished Seventh Chords at the Piano