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C♯ diminished 7th chord on bass (C♯dim7)
Also called or written C♯dim7 or C♯°7
C♯ diminished 7th contains C♯, E, G, and B♭. Its shape at the 8th fret demands a wide stretch across all four strings.
How it is built
Formula 1, ♭3, ♭5, ♭♭7
- Root positionC♯–E–G–B♭C♯dim79-10-8-9
- First inversionE–G–B♭–C♯C♯dim7/E12-13-11-12
- Second inversionG–B♭–C♯–EC♯dim7/G3-4-2-3
- Third inversionB♭–C♯–E–GC♯dim7/B♭6-7-5-6
How do you play a C♯ diminished 7th chord on bass?
C♯ diminished 7th is played at the 8th fret as 9 10 8 9: middle finger on the E string at fret 9, pinky finger on the A string at fret 10, index finger on the D string at fret 8 and ring finger on the G string at fret 9.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 9 | 2 | C♯ (1) |
| 3 (A) | 10 | 4 | G (♭5) |
| 2 (D) | 8 | 1 | B♭ (6) |
| 1 (G) | 9 | 3 | E (♭3) |
AdvancedThe span from the index finger on the 2nd string to the pinky on the 3rd string requires significant finger independence.
C♯dim7/E inversion
C♯ diminished 7th is played at the 11th fret as 12 13 11 12: middle finger on the E string at fret 12, pinky finger on the A string at fret 13, index finger on the D string at fret 11 and ring finger on the G string at fret 12.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 12 | 2 | E (♭3) |
| 3 (A) | 13 | 4 | B♭ (6) |
| 2 (D) | 11 | 1 | C♯ (1) |
| 1 (G) | 12 | 3 | G (♭5) |
C♯dim7/G inversion
C♯ diminished 7th is played at the 2nd fret as 3 4 2 3: middle finger on the E string at fret 3, pinky finger on the A string at fret 4, index finger on the D string at fret 2 and ring finger on the G string at fret 3.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 3 | 2 | G (♭5) |
| 3 (A) | 4 | 4 | C♯ (1) |
| 2 (D) | 2 | 1 | E (♭3) |
| 1 (G) | 3 | 3 | B♭ (6) |
C♯dim7/B♭ inversion
C♯ diminished 7th is played at the 5th fret as 6 7 5 6: middle finger on the E string at fret 6, pinky finger on the A string at fret 7, index finger on the D string at fret 5 and ring finger on the G string at fret 6.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 6 | 2 | B♭ (6) |
| 3 (A) | 7 | 4 | E (♭3) |
| 2 (D) | 5 | 1 | G (♭5) |
| 1 (G) | 6 | 3 | C♯ (1) |
Why it sounds like that
C♯ diminished 7th is built from the intervals 1, ♭3, ♭5, and ♭♭7 — a stack of three minor 3rds. The diminished 5th between C♯ and G gives the chord its unstable, tense quality. Compare it with C♯ minor 7th flat 5th, which raises the seventh from B♭ to B.
What goes wrong with C♯ diminished 7th?
- Letting the ring finger collapse and mute the 1st string.
- Pressing the index finger too hard, causing the 2nd string to go sharp.
- Failing to keep the pinky curved, resulting in a muted 3rd string.
When to use it
C♯ diminished 7th often functions as a passing chord in jazz and classical progressions. It can resolve to C♯ minor 7th flat 5th or E♭ major. C♯ diminished 7th suits dramatic transitions and chromatic bass lines.
Changing to and from C♯ diminished 7th
- Sliding the shape down two frets to the 6th fret gives B diminished 7th.
- Sliding the shape up one fret to the 9th fret gives D diminished 7th.
Which voicing to use
The 8th fret position keeps C♯ as the lowest note, giving a clear root-position sound. The C♯dim7/E inversion places E in the bass, creating a darker, less stable voicing. Choose the root position for foundational bass lines and inversions for smoother voice leading.
Other C♯ chords
Common questions
How is C♯ diminished 7th written?
C♯ diminished 7th is written as C♯°7 or C♯dim7. The ASCII root is C#, so you can type C#dim7. It is also spelled D♭ in enharmonic notation for the same sounding root.
What is the difference between C♯ diminished 7th and C♯ minor 7th flat 5th?
C♯ diminished 7th has a double-flatted seventh (B♭), while C♯ minor 7th flat 5th has a minor seventh (B). The diminished 7th chord is more dissonant and symmetrical.
Why does C♯ diminished 7th sound so tense?
C♯ diminished 7th contains two diminished 5th intervals: C♯–G and E–B♭. These tritones create a strong pull toward resolution.