Major 7th b5
maj7b5
0 - 4 - 6 - 11Major + diminished 5th + major 7th (Lydian flavour)
About Major 7th b5
A major seventh flat five chord is a major seventh with its fifth lowered a semitone — in C that is C, E, G♭ and B, written Cmaj7♭5. In practice it is the Lydian sound written a different way: the note called a flattened fifth is heard as a raised fourth, and where a chart calls it one or the other says more about the writer than about the sound.
Notes and formula
The formula is 1 – 3 – ♭5 – 7, or 0 – 4 – 6 – 11 in semitones. A major seventh chord in which the perfect fifth has been replaced rather than joined.
That replacement matters more than it looks. Cmaj7♯11 keeps the G and adds F♯ above it; Cmaj7♭5 has no G at all, so the chord is thinner and the tritone between C and G♭ is exposed instead of buried.
How to play it
On piano it is C–E–G♭–B. Because the fifth is missing rather than doubled, the chord sits well in close position and does not need the spreading that a plain major seventh does.
On guitar the movable form is x3423x, sounding C–G♭–B–E. It is a comfortable shape, which is one reason the chord appears more often in guitar arrangements than its rarity in theory books would suggest.
Where it comes from
Lydian is the parent: raise the fourth degree of a major scale and the note you get is the same pitch as a lowered fifth. Build a seventh chord that uses it in place of the fifth and this is the result.
It also arises by omission. A rootless voicing of a dominant chord a tritone away can land on these four notes, which is why the shape turns up in jazz comping under a chord symbol that looks nothing like it.
How it sounds
Bright and unanchored. The major seventh keeps the chord from sounding unstable while the lowered fifth removes the note that would have made it sound settled, and the combination reads as floating rather than tense.
It suits sustained textures and suits melody badly: a singer landing on the fifth will be a semitone out, and arrangers who use the chord under a vocal line usually restore the G somewhere in the harmony.
Flat five or sharp eleven
Cmaj7♭5 has four notes and no perfect fifth. Cmaj7♯11 has five and keeps it. They are different chords that share three tones, and the ear can tell them apart because the presence of G changes how the raised fourth is heard.
Charts are inconsistent about this, and reading maj7♭5 as maj7♯11 is a common source of muddy voicings. If the arrangement already has a bass playing the fifth, the distinction is lost anyway.
Scales that contain it
Lydian fits without alteration and is the obvious choice. The Lydian augmented mode fits too if the harmony above the chord is moving.
Ionian does not: its perfect fourth clashes with the third and its perfect fifth contradicts the chord's defining note. This is one of the few major-seventh chords over which the plain major scale is wrong.
Frequently asked questions
What notes are in a Cmaj7♭5 chord?
C, E, G♭ and B — a major seventh chord with the fifth lowered rather than the fourth raised. On guitar, x3423x.
Is maj7♭5 the same as maj7♯11?
No, though they share three notes. Maj7♯11 keeps the perfect fifth and adds the raised fourth above it; maj7♭5 replaces the fifth altogether and has four notes instead of five.
When would I use it?
Over a Lydian passage, or as a lighter substitute for maj7♯11 when the voicing is getting crowded. It is a colour chord, not a functional one.