STRINGSCALES

A half-diminished b4 Scale — Guitar Fretboard Visualization

Low E string: F, G, A, B, C, Db, Eb at frets 1, 3, 5, 7, 8, 9, 11

A string: A, B, C, Db, Eb, F, G, A at frets 0, 2, 3, 4, 6, 8, 10, 12

D string: Eb, F, G, A, B, C, Db at frets 1, 3, 5, 7, 9, 10, 11

G string: G, A, B, C, Db, Eb, F, G at frets 0, 2, 4, 5, 6, 8, 10, 12

B string: B, C, Db, Eb, F, G, A, B at frets 0, 1, 2, 4, 6, 8, 10, 12

High E string: F, G, A, B, C, Db, Eb at frets 1, 3, 5, 7, 8, 9, 11

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A half-diminished b4

The half-diminished b4 scale, the sixth mode of the neapolitan major scale, takes the locrian #2 half-diminished sound and lowers the 4th as well. With the 3rd and 4th collapsed together it is nearly a cluster scale, keeping only the natural 2nd as breathing room. A specialist color for m7b5 chords in dense modern jazz writing.

it consists of these notes and degrees:

A

i°

Adim
B

II

D♭7no5/B
C

biii

Cm
D♭

bIV+

D♭aug
E♭

bV+

E♭aug
F

bVI

Fmaj
G

bVII

Gmaj♭5

Same notes, different mode

A half-diminished b4 uses the same notes as the scales below. Start from a different note and you get a new mode built on the very same note set.

B altered dominant double b3C neapolitan majorDb leading whole toneEb lydian augmented dominantF lydian dominant b6G major locrian

half diminished b4 in all 12 keys, with chords and related scales

tip
  • Nearly a cluster: with bIII (C) and b4 (Db) adjacent, arpeggiate root, b5 (Eb), b7 (G) first and add the packed middle notes as passing color.
  • Over a m7b5 chord in dense modern-jazz writing, the b4 (Db) acts as a blue third-below-the-third; resolve it down to bIII (C).
  • Keep the natural 2nd (B) as your breathing room; it is the only bright interval in the scale.
  • It is the sixth mode of neapolitan major: the parent fingering a major 3rd below A plays it directly.

How to play A half-diminished b4 on guitar

Open A carries the root, open B a major second above and open G a minor seventh, so a three-string drone needs no left hand. Fret 2 puts another root on the G string, so a low phrase never leaves the nut area. Tonic chord is Adim, and the set holds no functional dominant. B altered dominant double b3 borrows this fingering, sitting 2 semitones away, so the box covers two keys. Fret 9 ends the first shape.

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