Although he had stopped composing in 1960, Schaeffer did return to the studio in 1975 at the request of François Bayle (director of the GRM from 1966) and Bernard Durr, to collaborate with the latter on an exclusively electro-acoustic work entitled Le trièdre fertile. Originally composed as a soundtrack this piece remains as one of the most elusive yet fascinating works by Schaeffer. Highly recommended avant garde classic. Vinyl nice an shiny, play is loud and perfect.