Explainer: East Coast synths
It’s time to go Eastside and break apart Dr Bob’s groundbreaking approach to synthesis
Last issue, we explored Don Buchla’s esoteric West Coast method of modular synthesis. To recap, in a typical Buchla setup, a dual complex oscillator employs wavefolding and FM-style modulation to create a harmonically interesting tone, which is then attenuated and/or dampened by a low-pass gate. This form of sound is usually driven by sequencers, giving typical West Coast sounds a machine-made aesthetic synonymous with experimental electronic music.
While Don Buchla was seeking to create a synthesiser capable of generating out-there sounds controlled by machines, New York’s Dr Robert Moog was simultaneously building an electronic instrument with a more ‘conventional’ philosophy. Taking on feedback from his peers, Bob Moog created his legendary Moog Modular system: a monolithic collection of 70 individual modules housed in cabinets, connected via patch cables by the user. Most importantly for traditional musicians, however, was the the organ-style keyboard, which allowed performers to play the instrument in a familiar way.
Although Moog’s Modular wasn’t the first synthesiser, it’s recognised as the forefather of traditional designs, with many of his methods becoming the industry standard for analogue synths as we know them today. For starters, Moog’s subtractive approach to sound generation, while being the most simplistic, is also the most widespread. One or more voltage-controlled oscillators (VCOs) generate harmonic waveforms (sawtooth, square, triangle, etc), a blend of which is fed into a voltage-controlled filter, or VCF, which filters away harmonics. This signal feeds into a voltage-controlled amplifier (VCA), which controls level; and a four-stage ADSR envelope is used to sculpt the loudness of each note, filter response over time, or both.
Moog also pioneered the use of control voltages, whereby electrical signals are shuttled between modules via those aforementioned patch cables. CVs signals are piped out from sources such as envelopes and LFOs, and are used to control parameters such as oscillator pitch, filter frequency and VCA level. Bob’s volts-per-octave standard is also now a widely-used unit of pitch control in today’s hardware synths and modular Eurorack systems.
As discussed last month, Buchla’s West Coast systems use low-pass gates to attenuate a signal’s level and/or tone through the use of an LED coupled with a lightsensitive resistor, called a vactrol. A low-pass gate uses only two stages – attack and decay, or attack and release – and has an inherently slow, inflexible response. Moog’s East Coast envelope design, on the other hand, uses the now-familiar four stages: attack, decay, sustain and release. Compared to the West Coast approach, the results are snappier, more controllable and more musical.