Bb-alt7#5 Augmented
The Bb-alt7#5 chord is built from the notes Bb – Db – F# – Ab – Cb – C#.
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Also known as
Bb-alt9#5
Chord tones, one by one
BbRoot
Root
The fundamental note the chord is built on — Bb.
DbThird
Minor third
Three semitones — makes the chord minor (darker, sadder).
F#Fifth
Augmented fifth (♯5)
Eight semitones — a sharp fifth. Restless and dreamy, typical of augmented chords.
AbSeventh
Minor seventh (♭7)
Ten semitones — the dominant/minor seventh. Adds bluesy tension (7, m7).
CbExtension
Flat ninth (♭9)
A ♭9 — sharp, dissonant tension typical of altered dominant chords.
C#Extension
Sharp ninth (♯9)
A ♯9 — the gritty 'Hendrix' tension over a dominant chord.
🎼 Related scales
🎹 Modal analysis
This chord implies the Phrygian scale; its characteristic note is the ♭9 / ♭2.
🎸 Genres
Flamenco · Metal · Modal jazz