B7b5 guitar chord
A close-position chord with the second voice from the top lowered an octave. Sits on four adjacent strings.
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About B7b5 — drop 2 voicings
B7b5 is B, D#, F and A — B7 with the fifth lowered a semitone.
It sounds symmetrical and slightly unreal. The same four notes spell a 7♭5 a tritone away, which is exactly why one can stand in for the other.
B7b5 notes and formula
| B | D# | F | A |
|---|---|---|---|
| 1 | 3 | ♭5 | ♭7 |
Altered dominant — and the chord that makes the tritone substitution work.
Also written B7(b5), B7-5 or B7♭5. The same chord either way; which spelling you meet depends on who wrote the chart.
How to play B7b5
Take the four notes stacked as close together as they go, then drop the second voice from the top an octave. The gap it opens is what makes the chord sound like a chord rather than a cluster.
It lands on four adjacent strings, which is why it is the workhorse voicing on guitar.
B7b5 has 14 of them, on the bottom four strings, the top four strings and the middle four strings, from open position up to the 13th — every inversion the chord has: B in the bass, D# in the bass, F in the bass and A in the bass. The one to learn first is the F shape at the nut, which is the easiest grip here.
5 of them sit on the bottom four strings, so you can run the inversions up one set without changing strings — which is the whole reason to learn them as a family rather than as separate grips.
Start with x21201 — 1 open string and down at the nut. 1 of the 6 shapes here sits in open position. None of them needs a barre. Together they cover the neck from the 1st fret to the 14th.
| Frets | Where | Bass | Top | Hand |
|---|---|---|---|---|
| x21201 | open position | B, root position | F | 1 open string |
| x2324x | 2nd fret | B, root position | D# | all fretted |
| 7x786x | 6th fret | B, root position | F | all fretted |
| x-x-9-10-10-11 | 9th fret | B, root position | D# | all fretted |
| x-12-13-14-12-13 | 12th fret | A, 3rd inversion | F | all fretted |
| x-x-13-14-12-13 | 12th fret | D#, 1st inversion | F | all fretted |
The same notes rebuilt from scratch give 5 shell, 9 drop 3 and 1 open string voicings, each on its own page.
Tensions. A shell of B7b5, root, third and seventh, leaves a string free, and the tones that belong over it are the b9 (C), the 9 (C#), the #9 (C##), the b13 (G) and the 13 (G#).
How to use B7b5
B7b5 is a dominant with its tension raised, so it still points at E — harder than a plain seventh does, because the altered tones sit a semitone from where they are going.
Voice by voice, B7b5 → E. 3 voices move by a semitone, and one note is common to both chords.
| In B7b5 | Moves | In E |
|---|---|---|
| B, the root | stays where it is | B, the fifth |
| D#, the major third | rises a semitone | E, the root |
| F, the flat fifth | falls a semitone | E, the root |
| A, the flat seventh | falls a semitone | G#, the major third |
What to play over B7b5
Every note of B7b5 is in B whole tone, B lydian dominant, B altered and B half-whole diminished.
Chords near B7b5
Change one note of B7b5 and you have Bmaj7b5 (the flat seventh becomes a major seventh), Bm7b5 (the major third becomes a minor third), B7 (the flat fifth becomes a fifth), Baug7 (the flat fifth becomes a sharp fifth) or B9b5 (add the ninth).
B7b5 is an altered chord — a dominant seventh with its fifth or ninth moved. Altered dominant chords on every root.
On B7b5’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.