A Whole Half Diminished, Mapped for the Bass

A Whole Half Diminished runs 8 notes to the octave, laid across this seat's EADG fretboard with every A marked. A blues phrase is short and keeps coming home to one pitch; the marked notes are where it comes home to.

Unstable and eerie — alternating whole and half steps, with the b3, b5, and 6 spelling a diminished seventh chord in every direction. Ominous, symmetrical, and unresolved.

Heard in: Diminished seventh chords in classical and jazz, horror and suspense scores, Bartok and Stravinsky, and neoclassical metal.

On the bass a scale supplies the notes between one chord and the next — the steps a line takes on its way to the change — far more often than it is played as a run.

Whatever scale you start from, the blues bends it: the third and the seventh get pushed flat, or somewhere between flat and natural, and that pull against the chord underneath is most of what the idiom sounds like.