The Key of G at the Electric Bass Seat

Called in G, a tune has G – Am – Bm – C – D – Em – F#° available to it before anybody substitutes anything; the parallel minor, G minor, offers Gm – A° – Bb – Cm – Dm – Eb – F instead. The two-five-one that closes most choruses is built out of three of those seven.

The electric bass seat carries the amplified bottom — the same harmonic duty as the upright, played with a fingerboard that answers back and a sustain the room can hear over a backbeat. The chord tones are the same ones the upright would choose; what changes is that a note can be held through the bar instead of dying, so a line can lean on a chord rather than announce it.

Learn where the ii, the V and the I fall in G until the hand goes there without asking, and the substitution rules become edits to something you already know rather than new material.