C#7b5 guitar chord
The standard grips this chord is usually shown with.
- Tap a note to hear it
- Arrows change position
- Fingers, notes or intervals
- Play the chord
About C#7b5 — root position
C#7b5 is C#, E#, G and B — C#7 with the fifth lowered a semitone.
It sounds symmetrical and slightly unreal. The same four notes spell a 7♭5 a tritone away, which is exactly why one can stand in for the other.
C#7b5 notes and formula
| C# | E# | G | B |
|---|---|---|---|
| 1 | 3 | ♭5 | ♭7 |
Altered dominant — and the chord that makes the tritone substitution work.
Also written C#7(b5), C#7-5 or C#7♭5. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play C#7b5
C#7b5 in root position puts C# in the bass, which is the chord as it is spelled: the note it is named after underneath everything else.
4 of C#7b5’s 6 common shapes do this: x43001, x4546x, 9-x-9-10-8-x, x-x-11-12-12-13.
Start with x43001 — 2 open strings and only 3 fretted notes. 1 of the 6 shapes here sits in open position. None of them needs a barre. Together they cover the neck from the 1st fret to the 13th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x43001 | open position | C#, root position | E# | 2 open strings |
| x23423 | 2nd fret | B, 3rd inversion | G | all fretted |
| xx3423 | 2nd fret | E#, 1st inversion | G | all fretted |
| x4546x | 4th fret | C#, root position | E# | all fretted |
| 9-x-9-10-8-x | 8th fret | C#, root position | G | all fretted |
| x-x-11-12-12-13 | 11th fret | C#, root position | E# | all fretted |
The same notes rebuilt from scratch give 5 shell, 13 drop 2, 9 drop 3 and 6 open string voicings, each on its own page.
Tensions. A shell of C#7b5, root, third and seventh, leaves a string free, and the tones that belong over it are the b9 (D), the 9 (D#), the #9 (D##), the b13 (A) and the 13 (A#).
How to use C#7b5
C#7b5 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#7b5 → F#. 3 voices move by a semitone, and one note is common to both chords.
| In C#7b5 | 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 |
What to play over C#7b5
Every note of C#7b5 is in C# whole tone, C# lydian dominant, C# altered and C# half-whole diminished.
Chords near C#7b5
Change one note of C#7b5 and you have C#maj7b5 (the flat seventh becomes a major seventh), C#m7b5 (the major third becomes a minor third), C#7 (the flat fifth becomes a fifth), C#aug7 (the flat fifth becomes a sharp fifth) or C#9b5 (add the ninth).
C#7b5 is an altered chord — a dominant seventh with its fifth or ninth moved. Altered dominant chords on every root.
On C#7b5’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.