The four-note opening motif of Shine On You Crazy Diamond is one of the most recognizable guitar phrases ever played. Gilmour's Stratocaster through a Hiwatt with a compressor and delay produces a tone of infinite sustain and crystalline clarity. The notes ring out with an almost vocal quality, each one sustaining until the next is played. The tone relies on precise gain staging: enough sustain to carry each note but not so much distortion that clarity is lost.