C#9b5 guitar chord
The root left to the bass player. Frees a finger for a tension.
- Tap a note to hear it
- Arrows change position
- Fingers, notes or intervals
- Play the chord
About C#9b5 — rootless voicings
C#9b5 is C#, E#, G, B and D# — C#7b5 with the natural ninth added over it.
It sounds sleek and tense. Played as a tritone substitution the ♭5 is the root of the dominant it replaced.
C#9b5 notes and formula
| C# | E# | G | B | D# |
|---|---|---|---|---|
| 1 | 3 | ♭5 | ♭7 | 9 |
Altered dominant — commonly the tritone substitute.
Also written C#9(b5), C#9-5 or C#9♭5. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play C#9b5
Leave the root to the bass player. In a band nobody misses it, and the ear supplies it from the guide tones anyway.
The finger it frees goes to a tension, which is why these sound richer than the shape they came from rather than thinner.
C#9b5 has 13 of them, on the top four strings, the middle four strings and strings 5-3-2-1, from open position up to the 12th — every inversion the chord has: E# in the bass, G in the bass, B in the bass and D# in the bass. The one to learn first is the D# shape at the nut, which is the easiest grip here.
5 of them sit on the top four strings, so you can run the inversions up one set without changing strings — which is the whole reason to learn them as a family rather than as separate grips.
Start with 9-10-x-10-0-11 — no barre and 1 open string. None of the shapes for C#9b5 uses an open string, so every one of them is movable; the lowest sits at the 3rd fret. 2 of the 5 need a barre. Together they cover the neck from the 3rd fret to the 12th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x43443 | 3rd fret | C#, root position | G | barred |
| 989889 | 8th fret | C#, root position | C# | barred |
| 9-10-x-10-0-11 | 9th fret | C#, root position | D# | 1 open string |
| 9-10-9-10-x-11 | 9th fret | C#, root position | D# | all fretted |
| x-10-11-10-12-11 | 10th fret | G, 2nd inversion | D# | all fretted |
The same notes rebuilt from scratch give 8 shell voicings, each on its own page.
Tensions. A shell of C#9b5, root, third and seventh, leaves a string free, and the tones that belong over it are the b13 (A) and the 13 (A#).
How to use C#9b5
C#9b5 is a dominant with its tension raised, so it still points at F# — harder than a plain seventh does, because the altered tones sit a semitone from where they are going.
Voice by voice, C#9b5 → F#. 3 voices move by a semitone, and one note is common to both chords.
| In C#9b5 | Moves | In F# |
|---|---|---|
| C#, the root | stays where it is | C#, the fifth |
| E#, the major third | rises a semitone | F#, the root |
| G, the flat fifth | falls a semitone | F#, the root |
| B, the flat seventh | falls a semitone | A#, the major third |
| D#, the ninth | falls a whole tone | C#, the fifth |
What to play over C#9b5
Every note of C#9b5 is in C# whole tone and C# lydian dominant.
Chords near C#9b5
Change one note of C#9b5 and you have C#7b5 (drop the ninth), C#9 (the flat fifth becomes a fifth), C#aug9 (the flat fifth becomes a sharp fifth) or C#9#11 (add the fifth).
C#9b5 is an altered chord — a dominant seventh with its fifth or ninth moved. Altered dominant chords on every root.
On C#9b5’s sound and use this page follows Mark Levine, The Jazz Theory Book (Sher Music, 1995). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.