F#9b5 guitar chord
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.
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About F#9b5 — open string voicings
F#9b5 is F#, A#, C, E and G# — F#7b5 with the natural ninth added over it.
It sounds sleek and tense. Played as a tritone substitution the ♭5 is the root of the dominant it replaced.
F#9b5 notes and formula
| F# | A# | C | E | G# |
|---|---|---|---|---|
| 1 | 3 | ♭5 | ♭7 | 9 |
Altered dominant — commonly the tritone substitute.
Also written F#9(b5), F#9-5 or F#9♭5. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play F#9b5
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.
F#9b5 has 1 of them, only on strings 6-5-4-3-2-1, all of them at the 3rd fret — all in one inversion, so the bass note never moves. The one to learn first is the E shape at the 3rd fret, which is the easiest grip here.
Start with 2323x4 — no barre and down at the nut. 1 of the 6 shapes here sits in open position. 4 of the 6 need a barre. Together they cover the neck from the 1st fret to the 14th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| 212112 | 1st fret | F#, root position | F# | barred |
| 212110 | open position | F#, root position | E | barred |
| 2323x4 | 2nd fret | F#, root position | G# | all fretted |
| x34354 | 3rd fret | C, 2nd inversion | G# | all fretted |
| x98998 | 8th fret | F#, root position | C | barred |
| 14-13-14-13-13-14 | 13th fret | F#, root position | F# | barred |
The same notes rebuilt from scratch give 10 shell and 14 rootless voicings, each on its own page.
Tensions. A shell of F#9b5, root, third and seventh, leaves a string free, and the tones that belong over it are the b13 (D) and the 13 (D#).
How to use F#9b5
F#9b5 is a dominant with its tension raised, so it still points at B — harder than a plain seventh does, because the altered tones sit a semitone from where they are going.
Voice by voice, F#9b5 → B. 3 voices move by a semitone, and one note is common to both chords.
| In F#9b5 | Moves | In B |
|---|---|---|
| F#, the root | stays where it is | F#, the fifth |
| A#, the major third | rises a semitone | B, the root |
| C, the flat fifth | falls a semitone | B, the root |
| E, the flat seventh | falls a semitone | D#, the major third |
| G#, the ninth | falls a whole tone | F#, the fifth |
What to play over F#9b5
Every note of F#9b5 is in F# whole tone and F# lydian dominant.
Chords near F#9b5
Change one note of F#9b5 and you have F#7b5 (drop the ninth), F#9 (the flat fifth becomes a fifth), F#aug9 (the flat fifth becomes a sharp fifth) or F#9#11 (add the fifth).
F#9b5 is an altered chord — a dominant seventh with its fifth or ninth moved. Altered dominant chords on every root.
On F#9b5’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.