
The keyboard is being fed to the record head, but the sound you hear is coming from the playback head. The tape is being constantly erased/recorded/played at the same time
Move the tape and you hear the sound, stop the tape and the sound stops. Move the tape backwards and the last note is played reversed.
So the tape functions a bit like an expression pedal for the keyboard, you can hear pitch shifts when changing from forwards to backwards movement (when they reverse the note that’s just been played), but not when going from backwards to forwards movement (because you’re going from a recorded note to a live note)
You can get a wide range of notes for a constant bow speed simply by playing other notes on the keyboard as you play.
Its a neat idea, I like it a lot, and I love how far they push it in some of their other videos!
( , Sun 17 Aug 2025, 12:47, Reply)

I just assumed they had tapes with pure tones on them like that barcode scanner video.
( , Mon 18 Aug 2025, 1:27, Reply)