The concept of the “synthesizer,” introduced by RCA in 1955, was a considerable advance. Like the classical studio equipment, it built up tones from their component elements, But the manipulations that had been so tedious before may now be programed onto punched paper tapes which in turn control a bank of generators, filters, and other tone-shaping components in a more or less continuous performance.
The possibilities this opened up were first revealed on The Sound and Music of the RCA Electronic Music Synthesizer (RCA mono, LM 1922); it included tunes played “in the style of” a harpsichord, an organ, a hillbilly band, a dance band, and several imaginary instruments, including one “resembling a piano, but with deeper tone and faster action than can be achieved with a conventional piano.” Recordings by Babbitt, Luening, and Ussachevsky (among others) have since shown the further development of the instrument (now in its second version) and of the techniques developed on it.
The punched-tape pre-programing of the RCA suggests computer control, and computers have since been programed to generate music (though not on the RCA). But the RCA synthesizer’s responses moved in quantum jumps rather than continuously, and “programed or computerized attempts to automate ‘spontaneity’ were entirely a matter of guesswork [with] the musician . . . unable . . . to modify a sound as it was being produced,” according to Folkman. The difference becomes immediately apparent when the early Mark I synthesizer’s rendering of the Bach Fugue No, 2 in C minor from The Well Tempered Clavier (on LM 1922)Bach Fugue No, 2 in C minor is compared with the performance of the same work on the Switched-On Bach album: the Mark I performance seems stiff and wooden by comparison, with leaping level changes and stumbling ritards.
Only tone shapes are pre-programed on the Moog (by interconnecting its component wave-generating and shaping modules with extemal patch cords). As with traditional instruments, the sequence and timing of these pre-programed notes are controlled manually, mostly using keyboards, This element of human control allows new timing and phrasing flexibility.
And because the modules of the Moog are controlled continuously, not just in separate steps, rapid smooth transitions between effects are possible. And since these modules can be controlled by external voltages, and produce varying voltages as signals, their outputs can become either the notes we hear or control voltages for other modules or both.
The oscillators, for example, can produce periodic control voltages as well as periodic (pitched) tones; and these oscillations can, in turn, create a periodic variation in a tone’s pitch (vibrato), volume (tremolo), or even timbre. Transient generators can control non-recurring variances or be be triggered to produce desired attacks at the beginning of any note. Even random control voltages can be obtained by using part of the output from the white-noise generator.