Gb-alt7b5 Half-Diminished
The Gb-alt7b5 chord is built from the notes Gb – Bbb – Dbb – Fb – Abb – A.
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Chord tones, one by one
GbRoot
Root
The fundamental note the chord is built on — Gb.
BbbThird
Minor third
Three semitones — makes the chord minor (darker, sadder).
DbbFifth
Diminished fifth (♭5)
Six semitones — a flat fifth. Creates instability, typical of m7♭5 and diminished chords.
FbSeventh
Minor seventh (♭7)
Ten semitones — the dominant/minor seventh. Adds bluesy tension (7, m7).
AbbExtension
Flat ninth (♭9)
A ♭9 — sharp, dissonant tension typical of altered dominant chords.
AExtension
Sharp ninth (♯9)
A ♯9 — the gritty 'Hendrix' tension over a dominant chord.
🎼 Related scales
🎹 Modal analysis
This chord implies the Locrian scale; its characteristic note is the unstable ♭5.
🎸 Genres
Modern jazz · Post-bop · Fusion