B♯ Lydian — 7th chords
Four-note stacks of thirds on each degree — root, 3rd, 5th, 7th. The added 7th gives jazz, gospel, and modern classical voicings their distinctive colour.
All 7 seventh chords in sequence
Degree 1 · Imaj7B#maj7
Degree 2 · II7C##7
Degree 3 · iii7D##m7
Degree 4 · iv°7E##m7b5
Degree 5 · Vmaj7F##maj7
Degree 6 · vi7G##m7
Degree 7 · vii7A##m7