Space plays and stops
- Notes and intervals
- B#M3D##m3F##m3A#
B# Dominant 7, written B#7, is built from B#, D##, F## and A#: the root, major 3rd, 5th and minor 7th.
Its 3rd and 7th, D## and A#, are its guide tones: they say what kind of chord it is, so voicings are built around them and the root is often left to the bass. Gb7, a tritone away, has the same two notes the other way up, so it can stand in for B#7 as its tritone substitute.