Guitar: C# Half Whole Diminished Over the Changes

C# Half Whole Diminished runs 8 notes to the octave, laid out here on EADGBE 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.

A guitar chorus is a single line with the comp dropped, so a scale here is what the picking hand walks through between the two or three phrases it actually meant to play.

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.