Chords in the key of A minor on cavaquinho
The key of A minor has seven diatonic chords: Am, B°, C, DmDmDmDm, EmEmEmEm, F and G. As sevenths: Am7Am7Am7Am7, Bm7b5, Cmaj7Cmaj7Cmaj7Cmaj7, Dm7Dm7Dm7Dm7, Em7Em7Em7Em7, Fmaj7Fmaj7Fmaj7Fmaj7 and G7G7G7G7. They come from the A natural minor scale, A, B, C, D, E, F and G, one on each note. On cavaquinho, the shapes below are the seventh chords of every degree, and the tonic one has 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. Its four steel strings give a bright, sharp attack that cuts through the mix and drives the beat.
Seventh chords in A minor on cavaquinho
These are the chords of the natural minor scale. In practice the v often becomes V (major) or V7, borrowed from the harmonic minor, to create the leading tone that pulls back to the tonic.