Dominant ♭9

Maximum tension

Prove it — just do the practice exercise.
G7b9 Root Position
G (R)B (3)D (5)F (♭7)Ab (♭9)
The 7b9 is extremely tense:

• R – 3 – 5 – ♭7 – ♭9

The ♭9 creates a semitone above the root. Typically over the half-whole diminished scale.

Example: G7♭9 = G + B + D + F + Ab