Japanese Minoru Sato & ASUNA (Naoyuki Arashi) recorded 5 different tracks of harmonium (a reed organ), the sustained notes recorded into a specific glass tube like the one pictured at the top of this post – the glass tube adding its own frequency and harmonics to the organ notes. Their composing method is pure minimalism, since each track starts 1 minute after the previous one (according to diagram above), slowly building an impressive, resplendent organ drone. [You might want to check their radical‘Valve/Membrance’ video on youtube and an interesting documentary on Archive.org.]
