Cdim7 chord on cavaquinho
Cdim7 is the diminished seventh chord: C, Eb, Gb and A (1–b3–b5–bb7). On cavaquinho, the diagram shape is 1 2 1 4, with Eb in the bass.
On the cavaquinho, four steel strings tuned D–G–B–D pack the chord into a small, bright space — every finger counts. In this Cdim7 voicing the bass is Eb and the shape runs from fret 1 to 4. Its four steel strings give a bright, sharp attack that cuts through the mix and drives the beat.
Notes and formula of Cdim7
Notes in Cdim7: C – Eb – Gb – AFormula: 1 – b3 – b5 – bb7In the formula, the numbers count steps of the major scale starting from the note that names the chord; "b" lowers a half step, "#" raises one — and a slash names the bass note.
Where to use it
Between two neighbouring chords it acts as a half-step stair: in C → C#° → DmDmDmDm it is the little step that pushes the music forward. In practice it is a passing chord — you barely notice it, but you feel the motion.
See also
Part of the Sevenths family.