G Blues — Puerto Rican Cuatro (Antiguo A-D-G-C-F)

G Blues is 6 notes to the octave (blues family), drawn here across the Puerto Rican Cuatro (Antiguo A-D-G-C-F)'s A-D-G-C-F strings with every G marked, so home stays visible from anywhere in the pattern.

The minor pentatonic with a b5 "blue note" wedged in — that one extra note adds grit, tension, and a sly, vocal quality. Tough, expressive, and unmistakably bluesy.

Heard in: Blues, rock, jazz, rhythm and blues, and boogie-woogie — Delta and Chicago blues, Hendrix, Clapton, Stevie Ray Vaughan.

Five courses spanning a minor thirteenth give a scale room to breathe: three or four notes to a course in first position, and a top string clear enough that a melody can live there while the rest of the grip stays down. These maps light every root so a run knows where home is before it leaves.

Work it in one position before you work it up the neck. The doubled courses forgive nothing: a fret held half a millimetre short buzzes on one string of the pair and rings on the other, and that difference is audible long before the run is fast.