1987 Buchla 700 with MIDI
A direct descendent in a prestigious line of electronic musical instruments, the Buchla 700 continues a tradition of combining inventive musical.and instrumental concepts with state-of-the-art electronics technology.
The 700’S architecture includes four dedicated computers, each of a different nature, and each optimized to its particular function. The nerve center of the instrument is a general purpose digital computer. Responsible for user communication, data processing, and supervisory control, this “host” computer can be programmed to accommodate varied musical needs.
A second computer “massages” incoming data. It directs conversion of analog voltages into digital form, discards redundant information, and transmits essential data to the host computer.
Receiving instructions and data from the host, a third computer (called the multiple arbitrary function generator) directs the instantaneous progress of 190 acoustic variables, each with a time resolution of 1/2000 of a second. This facility enables specification of complex sonic detail and extends the possibilities for expressive control.
A fourth computer, essentially a pipelined digital signal processor (DSP), is responsible for producing the 700’s twelve voices. Built into this computer are unusually powerful algorithms for sound generation, including frequency modulation, waveshape interpolation, and timbre modulation (unique to the Buchla, this technique significantly augments the electronic vocabulary.
Custom analog circuitry, with a dynamic range of 100 dB, is used for metering and control of dynamics. Specialized phasing and location circuitry provides unusual depth and imaging in the resultant acoustic field and enables independent location of each voice in stereo space.
Based on sealed membrane technology, the 700’s input structure provides a comprehensive interactive editing and mode selection facility. Position-sensitive transducers are used to implement conceptual potentiometers, flywheels, switches, ribbon controllers, and other gesture-sensitive paraphernalia. Light emitting diodes display the status of touch sensitive keys, and a super-twisted liquid crystal display indicates the functions and settings of touch sensitive controls.
Three MIDI ports comprise the 700’s primary performance inputs. Under software control, MIDI channels from any port(s) can be assigned to any of the 700’s voices, thus enabling simultaneous control from multiple MIDI devices (which might include keyboards, guitar controllers, drum machines, pitch followers, space wands or personal computers). Other inputs accept control voltages, pulses, foot pedals, and SMPTE time code. Two RS232 ports provide for communication with computers, modems, terminals, and printers. Control voltage and pulse outputs, three MIDI outputs, and special control signal outputs complete the 700’s comprehensive I/O facility.
In addition to the self-contained LCD display, the 700 can drive an external video monitor that conforms to the EGA standard. This high resolution, multi-color display, coupled with the 700’s extensive input structure and sophisticated high level music software, provides the instrument with an efficient interactive editing and performance environment. A built-in 3 1/2 inch disk drive is used to store data for subsequent retrieval or to facilitate software exchange with other users. Instrument definitions, tuning tables, waveshape tables, scores, and high level languages can all be stored on microdisks.
The 700’s software performs the essential function of defining the potential interaction between a musician and his instrument. The 700’s primary high-level language (called MIDAS VII) was designed in conjunction with the hardware; this close integration of hardware and software contributes to the instrument’s ease of operation and unusual versatility.
Designed for use by musicians (programming experience not required), MIDAS VII is both user-friendly and musically powerful. It incorporates several distinct facilities, each with its own display, and all sharing common editing procedures and modes of access. Brief descriptions of some of these facilities will perhaps suggest the nature and range of MIDAS VII.
The 700’s sonic output is defined with the instrument editor. Here is where the configuration of each of the voices is selected, the envelopes applied to various functions are determined, and waveshapes are selected. With as many as four oscillators and six modulators assignable to each voice, and several synthesis algorithms available, many interconnection schemes are possible. A configuration number determines how these resources are connected, and which modulation types apply.
Enveloping capabilities are extensive. For each voice, as many as 15 individual envelopes may be drawn for application to as many variables (four frequencies, six modulation indexes, filter frequency, resonance, level, dynamics, and location). An envelope may consist of as many as 96 segments, with individual points reacting to different input gestures, arid a variety of conditional actions (in addition to sustain) possible within each envelope.
All the instrument variables are simultaneously visible and readily edited by graphic or numeric means. When a desired sound is realized, it may be labeled, commented, and stored as one instrument in an “orchestra” of 40 instantly accessible instruments.
A waveshape editor allows the user to create or modify waveshape tables. A variety of editing techniques is available, including direct entry of numeric data or harmonic coefficients, as well as line: bending and curve fitting (particularly efficient forms of drawing). Fast specialized hardware permits transparent updating of waveshape tables and enables real time, glitch-free auditioning. With 2 waveshape tables assigned to each instrument, 24 waveshape tables may be addressed simultaneously by the 700’s 12 voices.
The tuning table editor allows the specification of completely arbitrary tunings, with any desired intervals and with no restraints on the number of notes per octave (with no octaves at all if you like). Entries are specified as musical pitches, with a resolution of 1 cent (1/100 of a semitone). Smart editing commands can direct the 700’s computer to assume much of the detail work in calculating and entering tuning data. (Just three entries would be required to create a 17 note equal-interval scale spanning an 88 key range.)
An assignment table directs the addressing of voices by MIDI ports, channel numbers, and/or individual keys. Voices may be grouped, and MIDI output channels may be assigned. Any combination of keyboard divisions may be specified, and multiple polyphony is supported.
The MIDAS score editor is a compositional facility without equal. Using linear time notation, a score can be generated through real-time performance input, and can be edited to the finest detail. Voices can be differentiated by color; analog variables can be stored and graphically displayed; changes in instrumentation, tempi, registration, location and tuning can be stored.
Various sorts of data can be organized as collections and stored on disk by the MIDAS librarian Record types include scores, instrument definitions, waveshape tables, assignment tables and tuning tables. A unique “conceptual typewriter” can be used to name records and add comments.
4 control voltage inputs / 4 control voltage outputs / 1 envelope follower output range: -10 to +10 volts / 2 foot pedal inputs range: 0 to 10 volts / 2 foot switch inputs action: momentary close
3 in, 3 out,1 through / 2 pulse inputs 2 pulse outputs level: 5 volts threshold: 1.5 volts
Auxiliary inputs 2 signal inputs: one can be modulated and processed; the other enters the final mix. level: 1.2 volts rms
Auxiliary outputs 2 signal outputs: one is a click track; the other can perform various control functions. level: 1.2 volts rms
sync in/out level: 5 volts threshold: 1.5 volts
SMPTE/tape in/outlevel: 1.2volts rms
2 channel stereophonic bus; ‘/4″ phone jacks plus ‘/4″ stereo headsetjack 12 individual voice outputs; miniphone connectors level: 1.2 volts rms, impedance: 600 ohms
Serial communications ports
2 RS232 ports, for communication with external host computer, terminal, and/or printer. Baud rates and protocol are under software control.
EGA standard for use with high resolution EGA or Multisync monitor connector: 9 pin Cannon (standard I.B.M. format)
voltage: 110 or 220 VAC / Power: 30 watts
weight: 9kg (20 pounds) dimensions: 47 x 38 x 12 cm (fits under a plane seat)
Circuitry and Architecture
supervisory control and data handling: 68000 based general purpose digital computer input processing: 6303 microcomputer with multiplexed flash analog to digital converter envelope generation: 190 channel multiple arbitrary function generator signal generation: pipelined, multiplexed 12 voice digital oscillator with PROM based microcode
waveshaping: multiplexed digital signal processor performing fast hardware interpolation signal processing (dynamics, location, filtering, phasing): voltage-controlled analog circuitry
primary editing inputs: 27 touch activated keys, 14 pots, 2 dimensional cursor control pad performance inputs: 24 touch sensitive keys, 3 MIDI ports, 4 foot pedal inputs software: MIDAS VII, a high level language for composition and performance displays: built-in high resolution LCD plus driver for external EGA color monitor