Callback
Improvise a duet with one of Karel's own recordings — he plays a phrase, then it's your turn, and every key you answer on is voiced by grains of his own piano sound.
Loads a real recording, then hands you a keyboard made of his sound.
Both his call and the grains under your keys come from this take.
Timbre grain
—
Each grain is a different attack sampled from his recording — the corpus your instrument is built from.
Routed through the shared ear-safety master bus.
Now
Waiting to begin
A loose 8-beat clock: 4 beats of his phrase, 4 beats for you, then he advances to the next phrase.