C#7b9 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#7b9 — open string voicings
C#7b9 is C#, E#, G#, B and D — C#9 with the ninth lowered a semitone.
It sounds dark and urgent. The flat ninth comes from the harmonic minor, so this is the V of a minor key rather than a major one.
Altered dominant — it points at a minor chord.
C#7b9 notes and formula
| C# | E# | G# | B | D |
|---|---|---|---|---|
| 1 | 3 | 5 | ♭7 | ♭9 |
Also written C#7(b9), C#7-9 or C#7♭9. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play C#7b9
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#7b9 has 3 of them, on the top four strings, the middle four strings and strings 6-4-3-2, from the 3rd fret up to the 6th — every inversion the chord has: B in the bass and D in the bass. The one to learn first is the D shape at the 3rd fret, which is the easiest grip here.
Five notes and four fingers, so something has to go. Keep E# and B (they fix the quality) and D (what the symbol is about). Let G# and C# go, in that order — a perfect fifth says nothing the root has not, and in a band the bass has the root.
Play C#7b9 as a shell — root, third and seventh — and the spare string takes the #11 (F##), 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.
- x43434, 3rd fret, C#, root position, top note G#, barred
- x40467, open position, C#, root position, top note B, 1 open string
- 98970x, 7th fret, C#, root position, top note D, 1 open string
- x-x-9-10-9-10, 9th fret, B, 3rd inversion, top note D, all fretted
- 9-11-9-10-9-10, 9th fret, C#, root position, top note D, barred
- x-x-11-10-12-10, 10th fret, C#, root position, top note D, all fretted
How to use C#7b9
C#7b9 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#m7b5→C#7b9→F#m7— the minor ii–V–i of F#.
Voice by voice, C#7b9 → F#m. 3 voices move by a semitone, and one note is common to both chords.
| In C#7b9 | Moves | In F#m |
|---|---|---|
| C#, the root | stays where it is | C#, the fifth |
| E#, the major third | rises a semitone | F#, the root |
| G#, the fifth | rises a semitone | A, the minor third |
| B, the flat seventh | falls a whole tone | A, the minor third |
| D, the flat ninth | falls a semitone | C#, the fifth |
What to play over C#7b9
Every note of C#7b9 is in C# half-whole diminished.
Chords near C#7b9
Change one note of C#7b9 and you have C#7 (drop the flat ninth), C#alt (the fifth becomes the sharp fifth), C#9 (the flat ninth becomes the ninth) or C#7#9 (the flat ninth becomes the sharp ninth).
C#7b9 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.