Gear Geek: Moog Minimoog Model D

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The Minimoog, which celebrated its 40th birthday last year, was the first synth to be considered a real musical instrument rather than custom-built studio equipment.

The Minimoog wasn''t Bob Moog''s idea; in fact, he was skeptical at first. After all, R.A. Moog had a reputation for building handcrafted modular instruments, and mass production sounded less than appealing to the man who is considered the father of modern synthesizers. Until that point, synthesizers were made-to-order studio gear, not musical instruments in the traditional sense—much too specialized to consider being sold in music stores. Besides, as the ''60s came to a close, Moog was deep in debt and couldn''t afford to tool up a production line.

Fortunately, one of Moog''s forward-thinking engineers, Bill Hemsath, began tinkering with designs for a compact synth in late 1969. Calling it the Min, Hemsath cobbled together Model A using spare parts from modular synths. He assembled several modules into a portable rig connected internally rather than by external patch cords. Other Moog engineers contributed ideas, and by the time Hemsath and rest of the design team had built two prototypes, Models B and C, Moog was leading the group effort.

Shortly thereafter, Moog sold the company and began working for its new owner, ensuring that production of the Minimoog Model D continued. Industry response was initially lukewarm at best, but once musicians began playing them onstage, Moog Music eventually sold about 12,000 Minimoogs between 1970 and 1980.

The Minimoog was the first synth whose signal path was hardwired rather than left up to the player, making it much easier to use than its predecessors. Its voltage-controlled circuits helped establish an architecture that soon became standard in other portable synths. The Minimoog had three relatively stable oscillators, each with a range down to one cycle every 10 seconds—hence, no need for a separate LFO. Moog''s patented 24dB-per-octave lowpass ladder filter and two contour (envelope) generators—which were hardwired to the filter and VCA—were adapted from the company''s modular instruments and simplified to cut costs. Jacks for processing external audio and external control sources, such as a sequencer or footpedal, furnished inputs from the outside world.

After its initial pre-production run, the Model D had several features lacking on previous Minimoog prototypes, including one of Hemsath''s innovations: wheels to control pitch bend and modulation. Moog, short on cash and not realizing what a significant contribution to real-time playability that wheels offered, never bothered to patent the design. Those wheels, along with the 44-note keyboard''s single triggering and low-note priority, gave the Minimoog an expressivity that eluded its competitors for years.

Today, used Minimoogs are still in demand. Most Model Ds still work perfectly—testament to their build quality. If you prefer soft synths, you can get emulations from Arturia, GForce, and other developers. The deluxe choice now, however, is the last synthesizer Bob Moog completed: the Minimoog Voyager.

Former senior editor Geary Yelton has reviewed synthesizers for EM since its very first issue in 1985. He lives in the heart of the Blue Ridge Mountains in Asheville, N.C.