John Cage described Variations VII as “a musical composition for a multitude of sound sources,” and he wanted  the ”use of sounds available at time of performance. No previously prepared sounds."

For some of the sound inputs, 10 telephones were installed by the New York Telephone Company in the Armory near the performance area. Just before the performance, Cage called pre-arranged places and left the receivers off their hooks. The places included Lüchows Restaurant, the 14th Street Con Edison power generating station, a New York city Department of Sanitation garbage depot, the holding room for dogs at the ASPCA, The New York Times printing presses, Merce Cunningham's studio, and Terry Riley’s living room near the motor for circulating water in his turtle tank.  Magnetic pickups on the handsets fed these sounds into the system. 

David Behrman was wired to produce brainwaves.  Contact microphones were placed on household machines: a blender, a juicer, fans, etc. Radio bands, Geiger counters, oscillators and pulse generators completed the sound sources. These sources fed into sound modulation equipment devised by David Tudor and from there into multiple speakers: the 12 stationary speakers mounted on the balcony surrounding the Armory space, Tudor's horn speaker, and speaker hung from the ceiling speaker.

The performers, John Cage, David Tudor, David Behrman and Tony Gnazzo, freely moved along the tables filled with equipment, activating the sound sources and feeding them into the system, following Cage’s idea: “no score no parts / free manipulation of available receivers / making audible what is otherwise silent /therefore no interposition of intention / just facilitating reception."

Cage also employed what he called “continuous sources triggered by photoelectric means.” Photocells were mounted along the inner edges of the performance tables, pointed at lights placed on the floor along the outer edges of the two tables. As the performers moved around and interrupted the light beams, different sound sources were activated and fed to the speakers.

There were large white screens in back of the performance area; and the lights used in the photocell system threw large shadows of the performers on these screens. 

For the second performance, audience members were encouraged to leave their seats, and many gathered around the performance tables, walked around the Armory floor or lay down on it to listen to the sound reverberating through the hall.