The background material "Anthem for 10 Cellos" by the composer Karl Yulievich Davydov, recorded with the Variophone electro-optical synthesizer. The author of "Variofon", which allows synthesizing artificial sound tracks in the technique of automated "drawn (graphic) sound" - Evgeny Alexandrovich Sholpo. The rhythmogram was created by the musicologist Semyon Lvovich Ginzburg. The recording was made on January 24, 1936.