How Ron Geesin and Pink Floyd Wrangled a 40-Piece Choir Onto Tape Loops for 'Atom Heart Mother'

The trickiest part of the “Atom Heart Mother” suite wasn’t the orchestration itself — it was that the band’s rhythm tracks were already committed to tape loops with no click track or timecode. Ron Geesin had to sit at Abbey Road with a stopwatch and a ruler, counting out where every brass hit and choir swell would land against a loop that could drift a few milliseconds each revolution. He literally scored the piece by marking up a paper copy of the tape waveform, then writing parts that would lock into the existing beat regardless of the loop’s imperfect cycle.

Geesin brought in a 40-strong choir and a brass section — none of whom could hear the band’s tape during recording because the Abbey Road playback system couldn’t feed it to them cleanly. Instead, Geesin conducted them to a separate click track he’d constructed from the loop’s pulse, but the click itself was slightly irregular, so every take required a new manual alignment. The result is a composition that feels symphonic but was actually built like a patchwork: the band’s looped drones, Geesin’s written brass and choral lines, and David Gilmour’s live guitar overdubs all glued together by sheer arithmetic.