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Dominant 7th ♯9 Chords on Piano

The dominant 7th ♯9 chord — the famous "Hendrix chord" — stacks a major third AND a minor third (written as ♯9) on top of a dominant 7th, creating a grinding, bluesy dissonance that defines rock, funk, and blues-jazz. The ♯9 is enharmonically the same as a minor third, so the chord contains both major and minor qualities simultaneously.

Formula: Root – Major 3rd – Perfect 5th – Minor 7th – Augmented 9th
Scale degrees: 1–3–5–♭7–♯9
Sound: Bluesy, gritty, Hendrix, funky
Symbol: 7♯9 (C7♯9)

Major and minor at the same time: The ♯9 (D♯ in C7♯9) is enharmonically E♭ — a minor third. So the chord has both E natural (major 3rd) and E♭ (minor 3rd). This clash between major and minor thirds is the source of its raw, bluesy power. Jimi Hendrix built "Purple Haze" on this sound.

Dominant 7th ♯9 Chord in All 18 Keys