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C♯ 7th flat 5 chord on bass (C♯7♭5)
Also called or written C♯7♭5, C♯, C♯ Dominant 7th Flat 5 or C♯ 7th ♭5
C♯ 7th flat 5 contains C♯, E♯, G and B. The 9th-fret shape is high on the neck, where the frets are close and the stretch is easier.
How it is built
Formula 1, 3, ♭5, ♭7
How do you play a C♯ 7th flat 5 chord on bass?
C♯ 7th flat 5 is played at the 9th fret as 9 10 9 10: index finger on the E string at fret 9, ring finger on the A string at fret 10, middle finger on the D string at fret 9 and pinky finger on the G string at fret 10.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 9 | 1 | C♯ (1) |
| 3 (A) | 10 | 3 | G (♭5) |
| 2 (D) | 9 | 2 | B (♭7) |
| 1 (G) | 10 | 4 | E♯ (3) |
AdvancedThe 9th-fret shape requires the pinky to reach fret 10 on the 1st string while the index holds fret 9 on the 4th string, stretching the left hand.
C♯7♭5/G inversion
C♯ 7th flat 5 is played at the 3rd fret as 3 4 3 4: index finger on the E string at fret 3, ring finger on the A string at fret 4, middle finger on the D string at fret 3 and pinky finger on the G string at fret 4.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 3 | 1 | G (♭5) |
| 3 (A) | 4 | 3 | C♯ (1) |
| 2 (D) | 3 | 2 | E♯ (3) |
| 1 (G) | 4 | 4 | B (♭7) |
Why it sounds like that
C♯ 7th flat 5 is built from the formula 1, 3, ♭5, ♭7. The diminished 5th between C♯ and G gives the chord its tense colour. Compare it with C♯ 7th, where the 5th is perfect.
What goes wrong with C♯ 7th flat 5?
- Letting the pinky collapse on the 1st string, which mutes the B at fret 10.
- Pressing the ring finger too flat on the 3rd string, so it deadens the 2nd string next to it.
- Striking the open 5th string, which is not part of the chord and adds an unwanted C♯.
When to use it
Use the supplied linked chords to hear its tension without adding unsupported harmony. Use it over C♯ 7th when the melody carries a ♭5. Its tense sound suits turnarounds and passing chords.
Changing to and from C♯ 7th flat 5
- Move to B 7th flat 5 by sliding the shape down two frets to the 7th fret.
- Move to D 7th flat 5 by sliding the shape up one fret to the 10th fret.
Which voicing to use
The 9th-fret shape keeps C♯ in the bass for a root-position sound. The C♯7♭5/G inversion at fret 3 puts the ♭5 in the bass, creating a darker, less stable feel.
Other C♯ chords
Common questions
How is C♯ 7th flat 5 written?
C♯ 7th flat 5 is written C♯7♭5 or C#7♭5. The symbol C♯ is also used, and the chord is sometimes called Dominant 7th Flat 5. It is also spelled D♭ in enharmonic notation for the same sounding root.
What is the difference between C♯7♭5 and C♯7?
C♯7♭5 has a diminished 5th (G) instead of the perfect 5th (G♯) in C♯7. That one note changes the chord from bluesy to tense and unresolved.
Can C♯7♭5 be used in place of C♯7?
C♯7♭5 can replace C♯7 when the melody or solo uses the ♭5. In a standard blues, the ♭5 may clash with the expected perfect 5th, so use it selectively.