Tools / Chords / C♯ 7th flat 5

C♯ 7th flat 5 chord on bass (C♯7♭5)

Also written C♯7♭5, C♯ or C♯ Dominant 7th Flat 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.

9th fret9-10-9-10

Positions on the neck1 of 2

How it’s built

C♯1Root

E♯3Major 3rd

G♭5Diminished 5th

B♭7Minor 7th

Formula 1, 3, ♭5, ♭7

Positions on the neck1 of 2

Inversions

The same three notes, with a different one in the bass.

Root positionC♯–E♯–G–BC♯7♭5Bass C♯

First inversionE♯–G–B–C♯C♯7♭5/E♯Bass E♯

Second inversionG–B–C♯–E♯C♯7♭5/GBass G

Third inversionB–C♯–E♯–GC♯7♭5/BBass B

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.

How do you play a C♯ 7th flat 5 chord on bass?

9th fret

Intermediate● On the diagram

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.

Tip — The 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.

String-by-string 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)

C♯7♭5/G inversion

Intermediate

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.

String-by-string 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)

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.

String

Fret

Finger

Note

4 (E)

C♯ (1)

3 (A)

G (♭5)

2 (D)

B (♭7)

1 (G)

E♯ (3)

String

Fret

Finger

Note

4 (E)

G (♭5)

3 (A)

C♯ (1)

2 (D)

E♯ (3)

1 (G)

B (♭7)