Evolution of Moog Synthesizers 1964-2002

The Core Specifications being used for comparison comprise the key ingredients in a synthesizer’s “voice”, or architecture. The number of components and the routing flexibility offered determine the depth and breadth of any particular synthesizer’s palette of potential sounds.

The Core Specifications presented throughout Moog's evolution are:

• VCOs (Voltage-Controlled Oscillators) - responsible for the basic pitch of the sound, and the initial waveform, which determines basic tonal content

• VCFs (Voltage-Controlled Filters) - responsible for further refining the initial waveform from the VCOs. The most common VCF is a Low-pass Filter (LPF), and Bob Moog is responsible for the most famous and popular LPF in the history of synthesizers

• VCAs (Voltage Controlled Amplifiers) - as the name suggests, primarily responsible for the amplitude (volume level) of the output from the VCF. A VCA is always at the end of the signal path in a synthesizer’s voice, but additional VCAs can be used to control the amplitude of other signals within the architecture

• LFOs (Low Frequency Oscillators) - oscillators typically tuned below human hearing range. Instead of being used as an audio source, they are used for their voltage content to control (“modulate” in synthesizer terminology) other components. The most common LFO application is to impart vibrato, sending a continuous sine or triangle wave to control the pitch of the VCOs

• EGs (Envelope Generators) - also called Contour Generators in some Moog models. EGs are responsible for adding “shape” to sounds by sending rising and falling voltages to VCFs and VCAs for tone and volume changes over time. These voltage events can also be routed to other components in the synthesizer. The most common type of EG is the ADSR (Attack Decay Sustain Release), but there have been numerous combinations of those 4 characteristics in different EG circuits over the years

• Polyphony - the number of voices (notes) that a synthesizer can play simultaneously

The early breadboard stage of the Moog prototype was referred to as "The Abominatron" in the first communications between Bob Moog and Herb Deutsch. At that point, the instrument could play chords. But the complexity of some sounds generated by modulating the two sound sources against each other led to Bob's decision to make it a monophonic instrument instead. That decision was manifested here, in Herb's monophonic prototype instrument.

Core Specifications:
2 VCOs, 2 VCAs

While the first several Moog synthesizers sold were custom instruments, eventually the most common components would be combined into three different configurations, with different sizes intended for different players. There were studio and portable versions available for each size, with the former housed in wooden cabinetry and the latter in suitcase-like enclosures.

In addition to the core components presented throughout this exhibit, early Moog modulars included a Fixed Filter Bank, revered for its precision in shaping sounds, and oscillators which could function as either audio sources or as LFOs. These oscillators were combined with Oscillator Driver modules which provided an expanded range of control compared to the self-contained VCO modules.

Synthesizer I

Offered limited complexity, meeting basic compositional needs. The components for the Ic (the studio designation) were housed in a single, wedge-shaped wood cabinet. The Ip (for portable) had room in its two suitcase-style cabinets for additional components.

Core Specifications:
1 VCO with mixable waveforms, 2 oscillators under the control of an Oscillator Driver, 1 Fixed Filter Bank, 1 VCF, 2 VCAs, 2 EGs (ADSR), Monophonic

Synthesizer II

Designed for moderately complex applications, including electronic music studios and university labs. An extra rectangular cabinet was added to the Synthesizer Ic to house the added components in this expanded version.

Core Specifications:
1 VCO with mixable waveforms, 5 Oscillators under the control of 2 Oscillator Drivers, 1 Fixed Filter Bank, 2 VCFs, 2 VCAs, 2 EGs (ADSR), Monophonic

Synthesizer III

Fully-implemented with first generation Moog components, Synthesizer III added a third suitcase cabinet in the portable version. The studio version presented the now-iconic look of a Moog modular system with its fully-loaded wedge and rectangular cabinets.

Core Specifications:
1 VCO with mixable waveforms, 9 Oscillators under the control of 3 Oscillator Drivers, 1 Fixed Filter Bank, 2 VCFs, 3 VCAs, 3 EGs (ADSR), Monophonic

The original Minimoog Model D is arguably the most iconic and revered synthesizer of all time. Its design incorporated hard-wiring of the most common synthesizer routings, making for a more portable and cost-effective alternative to its larger modular predecessors.

Launched in late 1970, it would be the first production model synthesizer to be sold by musical instrument dealers. Over the years, Minimoogs would wind up on thousands of recordings and concert stages, offering that unmistakable warm, robust Moog sound each and every time.

Core Specifications:
3 VCOs with selectable waveforms (the third oscillator could be switched to function as an LFO), 1 VCF, 1 VCA, 2 EG’s (ADS with a switch to add Final Decay, a version of Release), monophonic

The early ’70s saw the release of five new synthesizer systems from Moog, starting with the Model 10, the smallest Moog modular to date, housed in a single suitcase-style cabinet. It would be superseded by the Model 12, with the same mix of components, but featuring a new VCO design with greater pitch stability, and a new keyboard design.

Core Specifications:
1 VCO with mixable waveforms, 2 Fixed-Frequency Oscillators under the control of an Oscillator Driver, 1 Fixed Filter Bank, 1 VCF, 1 VCA, 2 EGs (ADSR), monophonic

The Model 15 offered a basic synthesizer voice in a portable, suitcase-style enclosure, with a complement of modules similar to Synthesizer I.

Core Specifications:
1 VCO, 2 Oscillators under the control of an Oscillator Driver, 1 Fixed Filter Bank, 1 VCF, 2 VCAs, 2 EGs (ADSR), monophonic

Using a similar wedge-shaped wood housing to the Synthesizer II, the Moog System 35 offered a broader complement of modules to meet the needs of advanced studio and educational installations.

Core Specifications:
1 VCO, 4 Oscillators under the control of 2 Oscillator Drivers, 1 Fixed Filter Bank, 2 VCFs, 3 VCAs, 3 EGs (ADSR), monophonic

Presented in a two-cabinet package similar to Synthesizer III, the Moog System 55 represented the largest complement of modules ever offered in a Moog production instrument.

Core Specifications:
1 VCO, 6 Oscillators under the control of 2 Oscillator Drivers, 1 Fixed Filter Bank, 2 VCFs, 5 VCAs, 5 EGs (ADSR), monophonic

This education-oriented Moog had several unique aspects when compared to the rest of the Moog synthesizer family. Its original design was not by Moog. The original Sonic V, designed by former Moog engineer Gene Zumchek, was a product from muSonics, a company that wound up buying out the original R. A. Moog Co. After that transaction, the Sonic V was reimagined to the portable suitcase version, the Sonic Six, with its built-in amp and speaker making for simplified classroom instruction.

It was also duophonic, allowing its 2 VCOs to each be controlled by a different key, and the temperament of the VCOs could be adjusted for creating microtonal scales. Perhaps the most interesting difference was the Sonic Six’s LFO implementation. It offered two dedicated components, with a variety of waveforms, and a mixer that blended their signals before they were routed through the instrument.

Core Specifications:
2 VCOs, 1 VCF, 1 VCA, 2 LFOs, 1 EG (AR with a switch for Sustain on/off), Duophonic

As synthesizers became more mainstream, a need developed for a simpler way of delivering new sounds, especially to the home organ market. Numerous manufacturers offered preset synthesizers, including Moog, with their Satellite. It featured pre-wired sounds available at the flip of a switch instead of the typical control panel full of knobs and switches for crafting sounds. The presets could be edited somewhat with left hand controls wired to some of the most common synthesizer functions.

Core Specifications:
1 VCO, 1 VCF, 1 VCA, 2 EGs (ADSR), 1 LFO, Monophonic

As synthesizers grew in popularity so did the need for manufacturers to offer instruments at more affordable price points. By scaling down the Minimoog’s feature set, Moog was able to offer the Micromoog for considerably less, making their instruments available to more musicians.

Costs were managed by using a smaller keyboard, a single VCO (with a sub octave function), replacing some variable controls with simpler switches, and by using a mostly plastic housing compared to the wood and metal used in the original Minimoog.

Core Specifications:
1 VCO (with Sub-Oscillator providing a signal 1 or 2 octaves below the VCO pitch), 1 VCF, 1 VCA, 2 EGs (AR with a switch for Sustain on/off), 1 LFO, Monophonic

A rare preset synthesizer from Moog, the Minitmoog was a souped-up version of the Satellite, available for a limited time within its predecessor’s lifespan. The Minitmoog featured two oscillators, with an oscillator sync function that made for an edgier sound quality.

The Minitmoog was one of the first synthesizers to offer a force-sensitive keyboard, allowing for extra expression by pressing on the keys after a note was played.

Core Specifications:
2 VCOs with Sync, 1 VCF, 1 VCA, 2 EGs (ADSR), 1 LFO, Monophonic

The original Polymoog, for the most part, was the brainchild of Moog Music engineer Dr. Dave Luce. As synthesizers became more mainstream, the demand for increased polyphony grew, but it outstripped the available technology. In an effort to offer a Moog synthesizer capable of playing chords, Luce received a patent for his unique approach to a divide-down oscillator, a component utilized in traditional organ technology.

While this made it possible to play chords (or all the notes of its 71-note keyboard at once if so desired), it did not offer discrete tone generators for each voice, making for a departure from traditional designs. A custom chip was used for each key to provide discrete filter, amplifier and envelope generator functions. Additionally, the Polymoog was the first Moog to feature velocity sensitivity, allowing the instrument to respond to a player's dynamics with changes in volume and timbre.

The Polymoog featured eight preset sound categories, with the ability to edit the sounds further, and it allowed two sounds to be played at once, in either split or layered applications.

The original Polymoog came out with a list price of US$5,500, and, as with its Moog predecessors, demand for a more affordable version soon surfaced. The Polymoog Keyboard 280a, introduced in 1978, was less expensive than the original, and offered more presets, but with fewer user parameters available for editing sounds.

While both versions gave keyboardists the ability to play chords with the iconic sound of the Moog Low-Pass Filter, with the release of the Sequential Circuits Prophet 5, the first polyphonic, programmable synthesizer, Polymoogs wound up fading away.

Core Specifications:
2 Divide-down Oscillators, 71 VCFs, 71 VCAs, 142 EGs (ADSR), 1 LFO, Polyphonic

Drawing inspiration from the organ market, the Taurus is a pedal-controlled Moog that wound up being extremely popular in the progressive rock genre. Originally it was part of a proposed ensemble system called the Constellation, which included the Lyra monophonic synthesizer and the polyphonic Apollo, which represented the roots of the Polymoog.

The Taurus featured three preset sounds, with a variable control panel under a protective lid for a fourth sound. A pair of slider controls with large foot pads allowed for the control of its Moog filter and amplifier volume.

Core Specifications:
2 VCOs, 1 VCF, 1 VCA, 1 EG (ASR), Monophonic

An expansion on the original design of the Micromoog, it used its predecessor’s circuit board combined with an additional circuit board incorporating additional features. The keyboard was not only larger than the Micro’s, it represented Moog’s second implementation of force sensitivity.

While it would be some time before synthesizer keyboards effectively responded to a player’s dynamics, the ability to add extra expression by pressing a key after playing greatly expanded the range of available sounds at the time.

Core Specifications:
2 VCOs with variable waveshapes, 1 VCF, 2 EGs (AR with a switch for Sustain on/off), 1 LFO, Monophonic

This small but mighty Moog was ground-breaking in that it offered a dual oscillator design at a price point comparable to other single oscillator instruments. By doing so the Prodigy offered sonic capabilities comparable to the Minimoog, but at a fraction of the price.

Core Specifications:
2 VCOs with selectable waveshapes, 1 VCF, 2 EGs (ADS with a switch to add Final Decay), 1 LFO, Monophonic

Conceptualized by Herb Deutsch, Bob Moog's inspiration in the creation of his first synthesizer, the Opus 3 was an ensemble instrument, combining multiple electronic music technologies into a single keyboard. With sections for Strings, Brass, and Organ, the Opus 3 was fully polyphonic, making for some complex layering possibilities. The Strings and Brass components each had their own classic Moog Low-Pass Filter for extensive sound shaping.



Core Specifications:
3 divide-down oscillators, 1 multi-mode string filter, 2 VCFs, 1 EG (ADS with a switch for Final Decay), Polyphonic

A unique strap-on synthesizer (known as a keytar in modern parlance), the Liberation was an early production model of a device that previously had only been available on a custom (i.e. very expensive) basis. It combined the equivalent of a souped-up Prodigy with a divide-down oscillator to provide a Polysynth section.

In a slight departure from previous Moog designs, the Liberation included more sliders than rotary knobs, and toggle switches instead of the slide switches found on previous Moog synths.

Core Specifications:
2 VCOs, 1 divide-down oscillator, 1 VCF, 1 VCA, 1 LFO, 2 EGs (ADS with a switch for Final Decay), Monophonic + Polyphonic

Another low-cost dual oscillator design, the Rogue offered a more limited sound palette compared to its Moog brethren. While waveshape and octave range were selectable, both oscillators shared the settings. There was also a single EG for controlling both the filter and amplifier functions.

Many classic Moog sounds, especially synth basses, were possible with the Rogue, but other classics were not possible due to these design decisions. The Rogue circuitry was licensed to Tandy, parent company of Radio Shack, and was incorporated, along with some additional features, into the Realistic Concertmate MG-1, the first synthesizer targeted towards home enthusiasts.

Core Specifications:
2 VCOs with selectable waveshapes, 1 VCF, 1 EG (AR with a switch for Sustain on/off), 1 LFO, Monophonic

As with their keyboard synthesizers, the popularity of the original Taurus pedal synthesizer created demand for a more affordable version. Not only did the Taurus II readily meet this need, it did so with a change in design concept which made for a more versatile instrument. The circuitry in the Taurus II was essentially the same as the Rogue, which was extremely well-suited for bass sounds despite being less flexible than its bigger brothers.

The Taurus II design comprised two components: a pedalboard controller (capable of outputting signals for controlling other synthesizers) and a control panel that mounted to the pedalboard with a microphone stand. This made it much easier for the performer to manipulate sounds while playing, and it included pitch and modulation wheels a la the Minimoog to provide even more sound control.

An auto-trigger function enabled the Taurus II to generate sequencer-like synthesizer bass with the single press of one of the pedals. An external audio input opened up access for other instruments to be processed through the classic Moog Low-Pass Filter.

Core Specifications:
2 VCOs with selectable waveshapes, 1 VCF, 1 EG (AR with a switch for Sustain on/off), 1 LFO, Monophonic

Monophonic Moogs entered the microprocessor age in 1981 with the release of the Source, and it made for a radical departure from earlier Moog look and feel. The legendary Moog sound was there, but the array of knobs and switches was replaced with touch switches and one data wheel. And while the Source did have wooden side panels, its colorful control panel of switches on a brushed aluminum chassis made for a futuristic look compared to the vintage style of the rest of the Moog family.

Core Specifications:
2 VCOs, 1 VCF, 1 VCA, 2 EGs (ADSR), 1 LFO, Monophonic

By the late ‘70s computer chips were powerful enough to manage the processes needed to deliver polyphonic, performance-oriented synthesizers, and the demand for such instruments was great. For all intents and purposes, the Memorymoog was a six-voice Minimoog, exactly what the marketplace wanted.

It featured computer memory for storing 100 sounds, and a unison mode for stacking all its oscillators on a single key. The Memorymoog Plus model added a sequencer, rudimentary Musical Instrument Digital Interface (MIDI) implementation, and a more stable oscillator design.

Core Specifications:

18 VCOs, 6 VCFs, 6 VCAs, 6 LFOs, 12 EGs (ADSR), 6-voice polyphonic

The last synthesizer designed by Bob Moog, Voyager represents a fitting culmination to his career arc. Combining the best aspects of the vintage Minimoog design with modern concepts, the Voyager brought Moog synthesizers into the 21st century, with computer memory for storing sounds, MIDI (Musical Instrument Digital Interface) implementation, a touch-sensitive control pad, and an updated version of the famous Moog filter, capable of stereo output.

A unique feature, pot mapping, allowed for the re-assignment of any of the Voyager’s knobs to suit the performer’s needs. Re-routing the headphone volume knob, a feature rarely used when performing live, was its most common use.

The familiar and revered Mini-style panel layout provided instant access to the most often-used functions, and an on-screen editing system gave Voyager users expanded access to deeper synthesizer parameters and component settings. A multi-pin connector allowed the Voyager to be combined with other Moog devices to create a system with modular synthesizer capabilities.

Core Specifications:
3 VCOs with variable waveshapes, 1 Dual VCF (configurable as High Pass/Low Pass or stereo Low Pass), 2 EGs (ADSR), 1 LFO, Monophonic