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A♭ half-diminished b4 Scale — Guitar Fretboard Visualization

Low E string: Fb, Gb, Ab, Bb, Cb, Dbb, Ebb, Fb at frets 0, 2, 4, 6, 7, 8, 10, 12

A string: Bb, Cb, Dbb, Ebb, Fb, Gb, Ab at frets 1, 2, 3, 5, 7, 9, 11

D string: Ebb, Fb, Gb, Ab, Bb, Cb, Dbb, Ebb at frets 0, 2, 4, 6, 8, 9, 10, 12

G string: Ab, Bb, Cb, Dbb, Ebb, Fb, Gb at frets 1, 3, 4, 5, 7, 9, 11

B string: Cb, Dbb, Ebb, Fb, Gb, Ab, Bb, Cb at frets 0, 1, 3, 5, 7, 9, 11, 12

High E string: Fb, Gb, Ab, Bb, Cb, Dbb, Ebb, Fb at frets 0, 2, 4, 6, 7, 8, 10, 12

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Ab 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°

A♭dim
B♭

II

D𝄫7no5/Bb
C♭

biii

C♭m
D𝄫

bIV+

D𝄫aug
E𝄫

bV+

E𝄫aug
F♭

bVI

F♭maj
G♭

bVII

G♭majb5

Same notes, different mode

Ab 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.

Bb altered dominant double b3Cb neapolitan majorC leading whole toneD lydian augmented dominantFb lydian dominant b6Gb major locrian

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

tip
  • Nearly a cluster: with bIII (B) and b4 (C) adjacent, arpeggiate root, b5 (D), b7 (Gb) first and add the packed middle notes as passing color.
  • Over a m7b5 chord in dense modern-jazz writing, the b4 (C) acts as a blue third-below-the-third; resolve it down to bIII (B).
  • Keep the natural 2nd (Bb) 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 Ab plays it directly.

How to play A♭ half-diminished b4 on guitar

Root on the G string at fret 1 is the easiest to reach, so a line can open with a single finger down. Both E strings give the minor sixth, with the minor third on open B, which lets open strings pedal under the shape. Capo 1 and G fingering applies. Bb altered dominant double b3 reuses this grip 2 frets up, so learning one covers both. Second position opens at fret 8.

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