An open string left ringing against a fretted grip. Because it costs no finger, it sounds a note the closed shape has none left for -- a tension on top, or a pedal root underneath. Either a familiar grip with open strings added, or a shape so sparse the open strings carry the chord. These belong to their key rather than to a shape, so D, A, G and E have many and Eb a handful.
G7#9 is G, B, D, F and A# — G9 with the ninth raised a semitone.
It sounds gritty and contradictory. The minor third sounding over the major third; every guitarist knows it as the Hendrix chord.

| G | B | D | F | A# |
|---|---|---|---|---|
| 1 | 3 | 5 | ♭7 | ♯9 |
Altered dominant — dominant function with a blues third on top.
Also written G7(#9), G7+9 or G7♯9. The same chord either way; which spelling you meet depends on who wrote the chart.
An open string left ringing against a fretted grip. It costs no finger, so it can sound a note the closed shape has none left for: a tension on top, or a pedal root underneath.
These belong to their key rather than to a shape: they cannot be moved up the neck. D, A, G and E have many; E♭ has a handful.
G7#9 has 4 of them, on strings 6-5-4-3-2-1, strings 5-4-3-2-1, strings 6-4-3-2-1 and strings 6-4-3-2, from the 2nd fret up to the 4th — every inversion the chord has: G in the bass, B in the bass and A# in the bass. The one to learn first is the G shape at the 2nd fret, which is the easiest grip here.
Start with 320301 — no barre and 2 open strings. 1 of the 10 shapes here sits in open position. 5 of the 10 need a barre. Together they cover the neck from the 1st fret to the 15th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| 320301 | open position | G, root position | F | 2 open strings |
| 3233xx | 2nd fret | G, root position | A# | barred |
| x23333 | 2nd fret | B, 1st inversion | G | barred |
| 353466 | 3rd fret | G, root position | A# | all fretted |
| 353436 | 3rd fret | G, root position | A# | barred |
| xx5466 | 4th fret | G, root position | A# | all fretted |
| x55466 | 4th fret | D, 2nd inversion | A# | all fretted |
| x-10-9-10-11-x | 9th fret | G, root position | A# | all fretted |
| x-13-12-12-12-13 | 12th fret | A#, 9th in the bass | F | barred |
| 15-14-15-15-15-15 | 14th fret | G, root position | G | barred |
The same notes rebuilt from scratch give 4 shell, 15 drop 2, 10 drop 3 and 15 rootless voicings, each on its own page.
Tensions. A shell of G7#9, root, third and seventh, leaves a string free, and the tones that belong over it are the #11 (C#), the b13 (Eb) and the 13 (E).
G7#9 is a dominant with its tension raised, so it still points at C — harder than a plain seventh does, because the altered tones sit a semitone from where they are going.
Voice by voice, G7#9 → C. 2 voices move by a semitone, and one note is common to both chords.
| In G7#9 | Moves | In C |
|---|---|---|
| G, the root | stays where it is | G, the fifth |
| B, the major third | rises a semitone | C, the root |
| D, the fifth | falls a whole tone | C, the root |
| F, the flat seventh | falls a semitone | E, the major third |
| A#, the sharp ninth | rises a whole tone | C, the root |
Every note of G7#9 is in G half-whole diminished.
Change one note of G7#9 and you have Gm7 (drop the major third), Gm9 (the major third becomes a ninth), G7 (drop the minor third), G9 (the minor third becomes a ninth), G7b9 (the minor third becomes a flat ninth) or G/F (drop the minor third).
G7#9 is an altered chord — a dominant seventh with its fifth or ninth moved. Altered dominant chords on every root.
On G7#9’s sound and use this page follows Mark Levine, The Jazz Theory Book (Sher Music, 1995). The shapes and the derived voicings come from different places, and both are explained in where the chords and the theory come from.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.