Dorian b5

The half-diminished chord with a natural sixth

Stacking thirds from the root gives C E♭ G♭ B♭ — a half-diminished seventh, the chord this scale exists to describe. What sets Dorian b5 apart from the usual choice over that chord is the sixth: A natural, not A♭. Held against the chord it sounds as a thirteenth, and it is the one note that makes the scale worth learning separately.

The comparison that matters is with Locrian natural 2, the sixth mode of melodic minor, which most players reach for over half-diminished chords. Both scales have the natural second and the flat fifth; they differ in the sixth alone. Locrian natural 2 has a flat sixth and sounds resigned, Dorian b5 has a natural sixth and sounds unsettled in a brighter way.

Where it comes from

Harmonic major is the major scale with a flattened sixth: C D E F G A♭ B. Reading those seven notes from the second degree gives D E F G A♭ B C, and transposed to C that is Dorian b5. Every mode of this family inherits the same interval of an augmented second, and here it sits between the flat fifth and the sixth.

That augmented second is audible and it is the family signature. In a run through the scale the gap between G♭ and A is wider than any other step, and lines built on the scale tend to either leap across it or use it as the turning point.

Using it over a two-five

In a minor ii–V–i, the ii chord is half-diminished, and Dorian b5 is one of two sensible scales for it. Choose it when the melody or the arrangement already contains the natural sixth, or when a flat sixth would collide with something in the voicing above.

Over the V chord the scale does not carry across: the harmony has moved and the natural sixth becomes a wrong note against an altered dominant. This is a one-chord scale, which is true of most of the harmonic major modes and worth saying plainly.

On guitar

Guitarists usually arrive at Dorian b5 from a Dorian shape by flattening the fifth, which is a single fret move on one string per octave. The rest of the fingering is untouched, and that is the fastest way to hear what the alteration does.

The harmonic major scale as a whole is easier to hold in the hand than its modes are to name: one shape, seven starting points. Practising the parent scale from each of its degrees teaches all seven modes at once, and it is how most players end up using this family in practice.

Frequently asked questions