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G♭ half-diminished b4 Scale — Guitar Fretboard Visualization

Low E string: Fb, Gb, Ab, Bbb, Cbb, Dbb, Ebb, Fb at frets 0, 2, 4, 5, 6, 8, 10, 12

A string: Bbb, Cbb, Dbb, Ebb, Fb, Gb, Ab, Bbb at frets 0, 1, 3, 5, 7, 9, 11, 12

D string: Ebb, Fb, Gb, Ab, Bbb, Cbb, Dbb, Ebb at frets 0, 2, 4, 6, 7, 8, 10, 12

G string: Ab, Bbb, Cbb, Dbb, Ebb, Fb, Gb at frets 1, 2, 3, 5, 7, 9, 11

B string: Dbb, Ebb, Fb, Gb, Ab, Bbb, Cbb at frets 1, 3, 5, 7, 9, 10, 11

High E string: Fb, Gb, Ab, Bbb, Cbb, Dbb, Ebb, Fb at frets 0, 2, 4, 5, 6, 8, 10, 12

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Gb 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:

G♭

i°

G♭dim
A♭

II

C𝄫7no5/Ab
B𝄫

biii

B𝄫m
C𝄫

bIV+

C𝄫aug
D𝄫

bV+

D𝄫aug
E𝄫

bVI

E𝄫maj
F♭

bVII

F♭majb5

Same notes, different mode

Gb 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.

Ab altered dominant double b3A neapolitan majorBb leading whole toneC lydian augmented dominantD lydian dominant b6Fb major locrian

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

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

How to play G♭ half-diminished b4 on guitar

Both E strings sound the minor seventh open and open A the minor third, so pedal tones are available without fretting. Fret 2 carries the lowest root, so the E-shape barre parks in the same place. Place a capo on fret 2 and E fingering covers it. Ab altered dominant double b3 runs the same box 2 frets higher, so nothing new is needed there. Fret 6 marks the end of position one.

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