C#7b5 guitar chord
An open string left ringing against a fretted grip. Because it costs no finger, it sounds a note the closed shape has none left for -- a tension on top, or a pedal root underneath. Either a familiar grip with open strings added, or a shape so sparse the open strings carry the chord. These belong to their key rather than to a shape, so D, A, G and E have many and Eb a handful.
- Tap a note to hear it
- Arrows change position
- Fingers, notes or intervals
- Play the chord
About C#7b5 — open string voicings
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.
Altered dominant — and the chord that makes the tritone substitution work.
C#7b5 notes and formula
| C# | E# | G | B |
|---|---|---|---|
| 1 | 3 | ♭5 | ♭7 |
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
An open string left ringing against a fretted grip. It costs no finger, so it can sound a note the closed shape has none left for: a tension on top, or a pedal root underneath.
These belong to their key rather than to a shape: they cannot be moved up the neck. D, A, G and E have many; E♭ has a handful.
C#7b5 has 6 of them, on strings 5-4-3-2-1, strings 6-5-4-3-2-1 and strings 6-4-3-2-1, from the 2nd fret up to the 6th — every inversion the chord has: C# in the bass, G in the bass and B in the bass. The one to learn first is the B shape at the 2nd fret, which is the easiest grip here.
3 of them sit on strings 6-4-3-2-1, 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.
Play C#7b5 as a shell — root, third and seventh — and the spare string takes the b9 (D), the 9 (D#), the #9 (D##), the b13 (A) or the 13 (A#).
All 6 common shapes as fret numbers, lowest string first. Hover or tap one to see it drawn.
- x43001, open position, C#, root position, top note E#, 2 open strings
- x23423, 2nd fret, B, 3rd inversion, top note G, all fretted
- xx3423, 2nd fret, E#, 1st inversion, top note G, all fretted
- x4546x, 4th fret, C#, root position, top note E#, all fretted
- 9-x-9-10-8-x, 8th fret, C#, root position, top note G, all fretted
- x-x-11-12-12-13, 11th fret, C#, root position, top note E#, all fretted
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.
In a phrase:G#m7→C#7b5→F#maj7— the ii–V–I of F#.
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 the major seventh), C#m7b5 (the major third becomes the minor third), C#7 (the flat fifth becomes the fifth), C#aug7 (the flat fifth becomes the 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.
The common shapes and the derived voicings come from different places, and both are explained in how this site is built.