Hear the intervals.
Play them. Feel the difference.
Here’s the part that changes everything. The box isn’t tied to A. It’s a shape — a pattern of finger movements on the neck. Move the whole thing up two frets and you’re in B minor. Move it down two and you’re in G minor.
The pattern is identical. Your fingers don’t learn anything new. Only the starting fret changes.
Choose a key to see where the box sits:
Box position: A minor (fret 5). Root notes highlighted.
This is why guitarists talk about positions — “playing out of the fifth position” means the box is sitting at fret 5. When someone calls a different key, you just move your hand.
The backing track here is still in A. To really hear G minor or B minor, you’d need a backing track in those keys — but try playing in the G or B position and notice how the notes feel different even over the A blues.