STRINGSCALES

B♭ half-diminished b4 Scale — Guitar Fretboard Visualization

Low E string: Fb, Gb, Ab, Bb, C, Db, Ebb, Fb at frets 0, 2, 4, 6, 8, 9, 10, 12

A string: Bb, C, Db, Ebb, Fb, Gb, Ab at frets 1, 3, 4, 5, 7, 9, 11

D string: Ebb, Fb, Gb, Ab, Bb, C, Db, Ebb at frets 0, 2, 4, 6, 8, 10, 11, 12

G string: Ab, Bb, C, Db, Ebb, Fb, Gb at frets 1, 3, 5, 6, 7, 9, 11

B string: C, Db, Ebb, Fb, Gb, Ab, Bb at frets 1, 2, 3, 5, 7, 9, 11

High E string: Fb, Gb, Ab, Bb, C, Db, Ebb, Fb at frets 0, 2, 4, 6, 8, 9, 10, 12

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Bb 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:

B♭

i°

B♭dim
C

II

E𝄫7no5/C
D♭

biii

D♭m
E𝄫

bIV+

E𝄫aug
F♭

bV+

F♭aug
G♭

bVI

G♭maj
A♭

bVII

A♭majb5

Same notes, different mode

Bb 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.

C altered dominant double b3Db neapolitan majorD leading whole toneFb lydian augmented dominantGb lydian dominant b6Ab major locrian

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

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

How to play B♭ half-diminished b4 on guitar

A-shape barre on fret 1 gives the lowest voicing available in this key, so nothing here demands a stretch. Open D sits on the diminished fourth and both E strings on the diminished fifth. Capo 1 puts everything under A fingering, which means the 6 flats stay off your fretting hand. C altered dominant double b3 runs this exact box 2 semitones along, so the grip is worth learning once. Fret 10 begins the second shape.

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