Space plays and stops
- Notes and intervals
- BbM3DM3F#2Ab
- Extends
- Bb Dominant 7
Bb Augmented 7, written Bb7#5, is built from Bb, D, F# and Ab: the root, major 3rd, sharp 5th and minor 7th.
Its 3rd and 7th, D and Ab, 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. E7, a tritone away, has the same two notes the other way up, so it can stand in for Bb7#5 as its tritone substitute.