C#dim13(#9) Diminished
The C#dim13(#9) chord is built from the notes C# – E – G – Bb – D## – A#.
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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.
D##Extension
Sharp ninth (♯9)
A ♯9 — the gritty 'Hendrix' tension over a dominant chord.
A#Extension
Thirteenth (13)
A 13th — full, rich top extension.
🎼 Related scales
🎹 Modal analysis
This chord implies the Whole-half diminished scale.
🎸 Genres
Bebop jazz · Hard bop · Gypsy jazz