Buchla 208 Stored Program Sound Source
A voltage-controlled analog synthesizer module with programmable patch storage, part of the Buchla 200 series and core of the 1973 Music Easel.
Overview
The Buchla 208 Stored Program Sound Source, sometimes called the "Electric Music Box," is a modular synthesizer unit for the Buchla 200 series. It was the heart of the 1973 Music Easel system. One unit that was examined was built after the 39th week of 1973, going by its IC date codes. The 208 works as a desktop synthesizer with extensive voltage control over pitch, timbre, and waveshape. It also stores and recalls instrument definitions on resistor-programmed cards. Low-authority sources sometimes confuse it with the Buchla Easel Command Desktop Synthesizer, but the 208 is a distinct module with its own role in Buchla's modular ecosystem.
Specifications
| Format | Occupies four panel units (in Buchla 200 Series cabinet) |
| Monitor output | Two-watt, will drive headsets or low-level speakers. |
| Modulation oscillator frequency range | 0.13 Hz to 70 Hz (with fine tune centered) |
| Complex oscillator frequency range | 38 Hz to 3500 Hz (with fine tune centered) |
| Power Consumption | 2.8W |
| Included Power Supply | 100-250VAC |
| Audio Outputs | Two mono audio outputs, a stereo headphone output |
| Audio Input | external mono audio input |
| Supplied with | six blank program cards, an assortment of programming resistors, and a comprehensive instruction |
Design
The primary signal source is the complex oscillator. A second complex oscillator on Card 9 generates sine and timbre waveforms that track the first. High-index bipolar modulation makes rich audio spectra, and pitch, timbre, and waveshape are all voltage controlled. The modulation oscillator can act as a signal source or as a modulator. Signal enveloping uses two low-pass gates, which can gate in the frequency and amplitude domains. Control voltage functions include a five-position sequencer with programmable pulses and a random voltage generator with four uncorrelated outputs. The envelope generator has voltage-controllable attack, duration, and decay. A voltage-controlled pulser provides triggers and additional envelope voltages. External signals go through a preamplifier and can control the unit through an envelope detector. The output section handles mixing, reverberation, monitoring, and level control. The unit contains 12 cards handling sequencer, random voltage, envelope generation, pulsing, modulation, oscillator, gate, preamp, and output functions. In early versions, the timbre circuit cross-modulates two triangle waveforms at the same frequency. DTL logic gates driven by comparators control integrator current reversal. Power comes in through an 8-pin keyed connector on the motherboard, and two ribbon cables link to the front panel jacks.
Context
The Buchla 208 is part of the Buchla 200 series. It was the central component of the 1973 Music Easel system, which combined a portable design with voltage control and patch storage.
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