The major ♯5 add9 chord combines a major third with an augmented fifth and adds a ninth extension. It is not a standard diatonic triad in common major-key harmony; it behaves more like a color chord that leans toward whole-tone and augmented sonorities while still keeping a recognizable major-third anchor. Use it when you want a floating, luminous tension that is not dominated by dominant-seventh grammar.
Construction
Practical formula: 1-3-♯5-9 (the seventh is absent in the symbol). In C(♯5add9), a common working set is C-E-G♯-D. Voice leading is important because ♯5 and 9 can create sharp intervals if cramped.
Usage
Appears in modern jazz, fusion, neo-soul, and cinematic pop as a momentary color on tonic-related harmony or as a reharmonization sparkle. It can also function as a passing chord between clearer major or minor sonorities.
Examples
- Neo-soul guitar voicings with add9 shimmer over altered fifth colors
- Fusion pads that avoid plain triads on static harmony
- Film scoring: brief “lift” chords before resolving to a simpler triad
Play
Spread the ninth above the augmented fifth region, keep the major third clear, and avoid stacking everything in one octave. If it sounds harsh, widen spacing and reduce doublings.
Ear-training cues
Hear major third plus a widened fifth and a ninth above: bright, unstable, and not inherently V7-like.
