A series of recordings with the Classic Quartet in the first half of 1965 show Coltrane's playing becoming increasingly abstract, with greater incorporation of devices like multiphonics, utilization of overtones, and playing in the altissimo register, as well as a mutated return to Coltrane's sheets of sound. In the studio, he all but abandoned his soprano to concentrate on the tenor saxophone. In addition, the quartet responded to the leader by playing with increasing freedom. The group's evolution can be traced through the recordings "The John Coltrane Quartet Plays", "Living Space" and "Transition" (both June 1965), "New Thing at Newport" (July 1965), "Sun Ship" (August 1965), and "First Meditations" (September 1965).