Boards of Canada’s “secret weapon” is likely to be one of three things.
-an analog signal interpreter that is using sacred geometry in some way (perhaps using rudimentary frequency tech as well).
-Mini sound baffle box, speaker in one end, mic on the other, using specifically arranged baffles and materials to dampen, shimmer, saturate, resonate, amplify, cancel out, echo, bounce, quantity, split, and otherwise change sounds. Think toy microphone but more sophisticated [“the way you show”]. And tube with nine rubbers in it (rubber discs) [“nine rubber wisdom”].
-playing back a sound at near silence in a quiet room, using our universe’s resonance found in pure silence; possibly utilizing spirits in the room to reinterpret the sound, before recording it again. Hence the mixed results.