Progressions in A — Puerto Rican Cuatro (Antiguo A-D-G-C-F)
Every chord the key of A owns, charted on A-D-G-C-F.
A major harmonises to A – Bm – C#m – D – E – F#m – G#°; A minor to Am – B° – C – Dm – Em – F – G. Each chord links to its Puerto Rican Cuatro (Antiguo A-D-G-C-F) grips, so a whole key becomes a short list of hand positions.
Most of this repertoire lives on three or four of these chords, and the interesting work is in what happens between them: the pick states a line, the grip lands underneath it, and the next change arrives before the ear has finished the last one.