Space plays and stops
- Notes and intervals
- BbM3DM3F#2Abm3Cb2C#
- Extends
- Bb Dominant 7
Bb Altered, written Bb7alt, is built from Bb, D, F#, Ab, Cb and C#: the root, major 3rd, sharp 5th, minor 7th, flat 9th and sharp 9th.
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 Bb7alt as its tritone substitute.
In the progressions here, Bb7alt is the V7alt of the Minor ii-V Progression in Eb and the VI7alt of the Minor ii-V to ii-V-I Progression in Db.