C7(#11) chord on cavaquinho
C7(#11) is the dominant sharp eleventh chord: C, E, G, Bb and F# (1–3–5–b7–#11). On cavaquinho, the diagram shape is 2 3 1 4, with E 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 C7(#11) voicing the bass is E and the shape runs from fret 1 to 4. Because this instrument has fewer strings than C7(#11) has notes, one note, usually the fifth, is normally dropped without losing the chord's identity. Its four steel strings give a bright, sharp attack that cuts through the mix and drives the beat.
Notes and formula of C7(#11)
Notes in C7(#11): C – E – G – Bb – F#Formula: 1 – 3 – 5 – b7 – #11In 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
You hear it a lot in jazz and bossa nova turnarounds — which simply means those short chord loops that close a section and set up the restart. It is also a classic ending color: a last chord that sounds like a question mark instead of a period.
See also
Part of the Altered dominants family.