Electric Bass: C# Half Whole Diminished Over the Changes
Where C# Half Whole Diminished lies at this seat, and what a chorus takes out of it.
C# Half Whole Diminished runs 8 notes to the octave, laid out here on EADG with every C# flagged. Mid-chorus the pattern is not what you need; where the root is when the chord changes underneath you is.
Tense, symmetrical, and slightly sinister — alternating half and whole steps pack in the b9, #9, #11, and 13, so it sounds like a dominant chord stretched to breaking point. Edgy, jazzy, and restless.
Heard in: Jazz lines over 13b9 dominant chords, fusion, film-noir and horror scoring — the sound of a V chord that refuses to settle.
The electric bass can hold a note long enough for it to be heard as a choice rather than a step, so a scale here is read for its strong tones first and its passing tones second.
Play it slowly against the audio until it stops being a shape, then put it over two bars of a form and let the chord tones decide which of the notes you actually keep.