C#dim7(b9) Diminished
The C#dim7(b9) chord is built from the notes C# – E – G – Bb – D.
Piano sound loads on first tap.
Also known as
C#dim7addb9C#o(addb9)C#o7(addb5b9)C#o7(b9)
Chord tones, one by one
C#Root
Root
The fundamental note the chord is built on — C#.
EThird
Minor third
Three semitones — makes the chord minor (darker, sadder).
GFifth
Diminished fifth (♭5)
Six semitones — a flat fifth. Creates instability, typical of m7♭5 and diminished chords.
BbSeventh
Diminished seventh (♭♭7)
Nine semitones — a doubly-flat seventh, found in fully diminished 7th chords.
DExtension
Flat ninth (♭9)
A ♭9 — sharp, dissonant tension typical of altered dominant chords.
🎼 Related scales
Locrian ♮6harmonic minor a semitone below
🎹 Modal analysis
This chord implies the Locrian ♮6 scale; its characteristic note is the natural 6th over a diminished chord. It is a mode of the harmonic minor a semitone below.
🎸 Genres
Modern jazz · Post-bop · Fusion