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C diminished major 7th chord on bass (CdimMaj7)
Also called or written CdimMaj7, CdimM7, C°M7, C augmented minor seventh or C minor seventh sharp five
C diminished major 7th contains C, E♭, G♭, and B. The 8th-fret shape places the root on the 4th string and requires a wide stretch.
How it is built
Formula 1, ♭3, ♭5, 7
- Root positionC–E♭–G♭–BCdimMaj78-9-9-8
- First inversionE♭–G♭–B–CCdimMaj7/E♭no shape on this instrument
- Second inversionG♭–B–C–E♭CdimMaj7/G♭no shape on this instrument
- Third inversionB–C–E♭–G♭CdimMaj7/Bno shape on this instrument
How do you play a C diminished major 7th chord on bass?
C diminished major 7th is played at the 8th fret as 8 9 9 8: index finger on the E string at fret 8, ring finger on the A string at fret 9, pinky finger on the D string at fret 9 and middle finger on the G string at fret 8.
Full note and interval breakdown
| String | Fret | Finger | Note |
|---|---|---|---|
| 4 (E) | 8 | 1 | C (1) |
| 3 (A) | 9 | 3 | G♭ (♭5) |
| 2 (D) | 9 | 4 | B (7) |
| 1 (G) | 8 | 2 | E♭ (♭3) |
AdvancedC diminished major 7th requires the ring finger and pinky to fret adjacent strings at the same fret while the index and middle hold the lower fret.
Why it sounds like that
C diminished major 7th is built from the formula 1, ♭3, ♭5, 7. The diminished 5th between C and G♭ creates a tritone that gives the chord its dark color. The major 7th B is a leading tone that resolves upward to C. Compare with C minor 7th flat 5th, which has B♭ instead of B.
What goes wrong with C diminished major 7th?
- Letting the ring finger mute the 2nd string, which silences the E♭.
- Pressing the pinky too lightly, causing the 2nd string to buzz.
- Allowing the index finger to drift sharp, making the 4th string note out of tune.
When to use it
C diminished major 7th works as a passing chord in C minor, often between C minor and C minor 7th. Its tense sound suits jazz ballads and dramatic film cues. Use it to add chromatic motion on the bass.
Changing to and from C diminished major 7th
- Sliding the shape down two frets to the 6th fret gives B♭ diminished major 7th.
- Sliding the shape up one fret to the 9th fret gives C♯ diminished major 7th.
Which voicing to use
The 8th-fret position places the root C on the 4th string, giving a solid low foundation. The shape is movable, so sliding it up or down changes the chord while keeping the same fingering.
Other C chords
Common questions
How is C diminished major 7th written?
C diminished major 7th is written C°M7 or CdimM7. The root is C.
What is the difference between C diminished major 7th and C minor 7th flat 5th?
C diminished major 7th has a major 7th (B), while C minor 7th flat 5th has a minor 7th (B♭). The major 7th creates a leading tone that pulls strongly to the octave.
Can C diminished major 7th be played in an open position?
No, the supplied voicing is at the 8th fret. The chord contains no open strings, so it can be moved to any fret to change the root.