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 referred to as the "Electric Music Box," is a modular synthesizer unit designed for the Buchla 200 series. A specific unit examined was manufactured after the 39th week of 1973, based on IC date codes, and it served as the heart of the 1973 Music Easel system. It functions as a desktop synthesizer with extensive voltage control over pitch, timbre, and waveshape, and includes unique capabilities for storing and recalling instrument definitions via resistor-programmed cards. Though sometimes confused with the Buchla Easel Command Desktop Synthesizer in low-authority sources, the 208 is a distinct module with a dedicated 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, with a second complex oscillator on Card 9 generating sine and timbre waveforms that track the first. High-index bipolar modulation creates rich audio spectra, and pitch, timbre, and waveshape are voltage controlled. The modulation oscillator can act as a signal source or modulator. Signal enveloping uses two low-pass gates capable of frequency and amplitude domain gating. Control voltage functions include a five-position sequencer with programmable pulses and a random voltage generator with four uncorrelated outputs. An envelope generator features voltage-controllable attack, duration, and decay. A voltage-controlled pulser provides triggers and additional envelope voltages. External signals are processed via 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 uses cross-modulation of two triangle waveforms at the same frequency. DTL logic gates driven by comparators control integrator current reversal. Power is delivered via 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 and was the central component of the 1973 Music Easel system, integrating portable design with advanced voltage control and patch storage.
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