James Bohn
During the sixties, One of the most unique and flexible sound sources used in EMS was the Harmonic Tone Generator. This unit was designed and built by James Beauchamp, who at that time had a fellowship in Electrical Engineering and Music that was funded by Magnavox. This fellowship was provided "for basic research into the generation and creation of new musical sounds." This research was conducted under Lejaren Hiller's supervision, and resulted primarily in the creation of the Harmonic Tone Generator. While the study was under Hiller¹s supervision, Beauchamp did the work on his own, designing and building it himself. The Harmonic Tone Generator produced a set of sine waves that were tuned to create an overtone series. Individual control over the amplitudes and phases of each harmonic was available. The Harmonic Tone Generator was first available in 1963, but at that time only provided three harmonics. A year later, a total of six harmonics was available. The frequency for the fundamental was variable between 0 and 2600 Hz.
The fundamental frequency was set through the use of two potentiometers, one of which provided gross control, the other providing fine control. Pitch could also be controlled by a keyboard, which caused the unit to produce equally-tempered semitones from C2 to E7 (65-2640 Hz). Two Frequency Modulation inputs were also provided. These inputs were summed together with the two potentiometers and the keyboard.
The amplitude of each harmonic could be set through the use of either an attenuator or an amplifier. Each harmonic had, in addition to these two knobs, three Amplitude Modulation inputs. The three inputs and the amplifier were summed and sent to the attenuator, which proided amplitude control over this summed value. Six Attack-Release envelope generators were available for use with the unit. One could utilize either a summed output or individual outputs of each harmonic.
A foot pedal controlled amplifier was provided as a step towards proposed live performances. One performance that utilized the Harmonic Tone Generator was the premiere of the Computer Cantata, where this unit was used in conjunction with a Theremin. Lejaren Hiller used this machine in the tape parts of Machine Music, A Triptych for Hieronymous, and Suite for Two Pianos and Tape. Other compositions that utilize the Harmonic Tone Generator include: Herbert Brün's Futility 1964, Kenneth Gaburo's Lemon Drops, Burt Levy's Gnomes, and Salvatore Martirano's Underworld.
