Zoë Blade's notebook

900 Series (Moog)

900 Series tech specs

Various modular synthesisers were made by Moog in the 1960s and 1970s, known as the 900 Series, 900 System, or simply Moog Modular, although there doesn't appear to be a definitive name for the range as a whole... or any one system in the range.

Moog's modular system grew out of various good ideas that Moog's clients had asked him to implement. In 1964, he prototyped a modular system with voltage control for Herb Deutsch. This was inspired by Harald Bode's modular system,[2] although Moog added a musical keyboard and introduced the 1V/Oct standard for relaying pitch information from the keyboard to the oscillators. Moog built VCAs, ADSR envelope generators, and envelope followers to Vladimir Ussachevsky's spec in 1965,[3] which presumably became the 902, 911, and 912 modules respectively. Also in 1965, for Gustav Ciamaga, Moog designed a voltage controlled filter.[4] This likely became the smooth, creamy sounding 904A which, along with an excess of detunable oscillators, gave his synthesiser its signature sound.

The whole range sounds great — and big — but if you're used to more recent modular synthesisers such as Roland's System-100M or Doepfer's A-100, bear in mind that equivalent patches on a Moog 900 Series might be significantly more longwinded. These systems were trailblazing, and so lack many modern conventions, from features through to terminology.

For example, the CV inputs of modules like the oscillators, amplifier, and filters don't have built-in attenuators to specify how much each control signal affects them. So you'll likely be using additional attenuator, amplifier, or mixer modules on the way into those.

A more sensible approach when dealing with modern clones might be to simply get that smooth, creamy filter, and combine it with modules from another system that has more modern conveniences. But then again, there is that aesthetic...


My favourite instrument is my old Moog III system, and I use its twelve envelope generators together to create specific sound shapes. It's also useful for treating the computer processed sounds, and even though working with this analogue system takes longer to set up (tuning, patching etc), it gives me plenty of freedom because I can choose all the connections independently — and that's impossible for my digital systems.

— Isao Tomita, 1983[5]

...a big Moog was ideal and it sounded good. It still sounds better than anything else around. I have a theory that every year the manufacturers make synthesizers that sound slightly less good but have more functions. But it's really quite peculiar that if you set up one sound on any of the synthesizers around at the moment and you set up the same sound on the Moog — particularly bass sounds — the Moog just has so much more punch and quality. And that's why it's still around.

— Hans Zimmer, 1986[6]

Standard configurations

The first series of complete systems were the Synthesizer I, Synthesizer II, and Synthesizer III from the 1960s.[7] These evolved into the Synthesizer Ic, Synthesizer IIc, and Synthesizer IIIc "console" (studio) versions, so named to differentiate them from the Synthesizer Ip, Synthesizer IIp, and Synthesizer IIIp,[8] their new "portable" equivalents that replaced the rather fetching walnut cases with black cases with handles.

Synthesizer Ic
901A 901B 901B 991 901 903A 905 907 904A 902 902 911 911 994  
CP3 CP3     CP4 CP8
950 / 956
Synthesizer IIc
960 961 903A 907 984
901A 901B 901B 901B 901A 901B 901B 901 905 904B 904C 904A 902 902 911 911
950 / 956
Synthesizer IIIc
914 905 992 904B 904C 904A 902 902 902 993 911 911A 911 911 912
901A 901B 901B 901B 901A 901B 901B 901B 901A 901B 901B 901B 901 903A 984
950 / 956

These were joined in the early 1970s by the portable Synthesizer 10 and Synthesizer 12,[9] and the Sequencer Complement A and Sequencer Complement B.[8] The complements were based around the new 960 Sequential Controller module, an analogue step sequencer, and both the A and B complements were available in studio or portable cases.

This time, the 960 wasn't based on something Moog had built for a friend, even though he had previously transistorised one of Raymond Scott's sequencers. Instead, it was based on rival Buchla's Sequential Voltage Source Model 123.

Sequencer Complement B
960 962 994 961 960 962

Finally, after a change of company ownership, the range was cut back to a more manageable three offerings: the portable Synthesizer 15, and the studio-bound Synthesizer 35 and Synthesizer 55. These all replaced the 901 oscillators with more stable, more featureful, and mostly more desirable 921 equivalents. Some also replaced the 903A noise generator with the 923, or the 907 fixed filter bank with the 914.[10] The Synthesizer 55 is especially opulent, offering an iconic three rows of modules towering above its keyboard, like its IIc and IIIc predecessors.

As this is all clearly too simple, yet more variations of these product names exist, replacing the "Synthesizer" with "Model", and eventually "System".

System 35
921A 921B 921B 923 921A 921B 921B 921 907 904B 904A 902 902 902 911 911 911
CP3A CP3A CP35   CP4 CP8
System 55
914 904B 904A 992 902 902 911 911   902 902 902 993 911 911A 911 911
921A 921B 921B 921B 921A 921B 921B 921B 921 995 903A 994 960 962


Model Type Released Description
901 5U module 1965[11] VCO (Doubles as LFO)
901A 5U module 1965[11] Oscillator controller
901B 5U module 1965[11] Oscillator
901C 5U module 1965[11] Output stage
901D 5U module 1965[11] Variable waveform output stages
902 5U module 1965[11] VCA
902A 5U module 1965[11] Bandpass filter adapter
903 5U module 1965[11] White noise
903A 5U module 1971[8] White and pink noise
904 5U module 1965[11] Multimode VCF
904A 5U module 1965[11] Lowpass VCF
904B 5U module 1965[11] Highpass VCF
904C 5U module 1965[11] Bandpass and notch VCF
905 5U module 1965[11] Spring reverb
906 5U module 1965[11] Impulse generator
907 5U module 1965[11] Fixed filter bank (8 bandpass, 1 low, 1 high)
910 5U module 1965[11] Power supply
911 5U module 1965[11] ADSR envelope generator
911A 5U module 1969[12] Dual trigger delay
912 5U module 1965[11] Envelope follower
913 5U module 1965[11] Triggered envelope generator
914 5U module 1972[13] Extended range fixed filter bank (12 bandpass, 1 low, 1 high)
920 5U module 1965[11] Power supply
921 5U module 1972[13] VCO (Doubles as LFO)
921A 5U module 1972[13] Oscillator controller
921B 5U module 1972[13] Oscillator
923 5U module 1974[14] Highpass and lowpass filters / White and pink noise
950 Controller 1965[11] Keyboard controller
950B Peripheral 1969[12] Scale programmer
951 Controller 1971[8] Keyboard controller
952 Controller 1972[13] Duophonic keyboard controller
955 Controller 1965[11] Ribbon controller
956 Controller 1969[12] Ribbon controller
958 Controller 1971[8] Foot pedal
959 Controller 1971[8] Joystick
960 5U module 1969[12] Sequential controller
961 5U module 1969[12] Interface
962 5U module 1969[12] Sequential switch
982 5U module 1965[11] Two-channel mixer
984 5U module 1965[11] Four-channel mixer
991 5U module 1971[8] Highpass and lowpass filters / attenuator
992 5U module 1971[8] Control voltages / attenuator
993 5U module 1971[8] Trigger / envelope voltages
994 5U module 1971[8] Multiples
995 5U module 1974[15] Attenuators
1120 Controller 1973[16] Foot pedal
1121 Controller 1973[16] Footswitch
1125 Peripheral 1973[16] Sample & hold
1130 Controller 1973[16] Percussion controller
1150 Controller 1973[16] Ribbon controller
1630 5U module 1972[17] Bode Frequency Shifter
1631 5U module 1972[17] Bode ring mod
1632 5U module 1972[17] Dual Bode ring mod
CP1 CP module 1971[8] CV and trigger out
CP11 CP module 1971[8] Mixer / multiples / attenuator / CV and trigger out / trunk lines / power switch
CP2 CP module 1971[8] Lowpass and highpass filters / multiples / CV and trigger out
CP3 CP module 1971[8] Mixer / trunk lines / CV switches / attenuator
CP35 CP module 1974[18] Normalled attenuators / CV sources / trunk lines
CP4 CP module 1971[8] CV switches / attenuator / trigger and envelope routing switches / CV and trigger out
CP5 CP module 1971[8] CV and trigger out / power switch
CP6 CP module 1971[8] CV switches / attenuator / trigger and envelope routing switches / multiples
CP7 CP module 1971[8] Trigger and envelope routing switches / multiples
CP8 CP module 1971[8] Power switch
CP9 CP module 1971[8] Power switch
RM-1 Rack 1967[7] 8-module rack
N/A Rack 1969[19] 12-module lower walnut rack
N/A Rack 1969[19] 12-module upper walnut rack
N/A Rack 1969[19] 22-module upper walnut rack


The 902 Voltage Controlled Amplifier could do with a tad more labelling. Its top input is positive, while its bottom input is negative; and its top output is negative, while its bottom output is positive. Useful, but not obvious.[20]

Notable users

Synthesizer IIIc

Synthesizer IIIp

System 15

System 55



  1. "Detail: Console Panel #5" R. A. Moog Co., Jan 1969
  2. "Harald Bode" Jay Lee, Polyphony, Sep 1981, pp. 14—17
  3. "An Interview With Bob Moog" 2000
  4. "Abominatron Tape Transfer, Part 2" Seva Ball, Mar 2010
  5. "Isao Tomita" Mike Beecher, Electronics & Music Maker, Feb 1983, pp. 50—52
  6. "No Presets Allowed" Ralph Denyer, Sound On Sound, Aug 1986, pp. 50—55
  7. "Electronic Music Composition-Performance Equipment Short Form Catalog — 1967" Moog, 1967
  8. "Moog 1971" Moog, 1971
  9. "Moog Synthesizer 12" Moog, 1973
  10. "Professional Synthesizers Catalogue '76" Moog, 1976
  11. "Ultra-Short Form Catalog of Electronic Music Composition Instruments" Moog, 1965
  12. "Prices of Synthesizers and Single-Function Instruments Currently Being Produced by R. A. Moog" Moog, 1969
  13. "Moog Component Price List" Moog, 1972
  14. "Moog Synthesizer 15" Moog, 1974
  15. "Moog Synthesizer 55" Moog, 1974
  16. "Moog Inc. Price List" Moog, 1973
  17. "Moog System Price List" Moog, 1972
  18. "Moog Synthesizer 35" Moog, 1974
  19. "R. A. Moog Supplementary Price List" Moog, 1969
  20. "902 VCA Lin v. Exp?" CZ Rider, Mar 2013
  21. "It's So Good: I Feel Love by Donna Summer Turns 45" Jude Rogers, The Quietus, Jun 2022
  22. Kosmos Isao Tomita, 1978
  23. The Bermuda Triangle Isao Tomita, 1979
  24. "Larry Fast" Steve Howell, Electronics & Music Maker, Jun 1983, pp. 41—42
  25. "Zoo 2000" Dan Goldstein, Electronics & Music Maker, Feb 1985, pp. 42—46
  26. "The French Connection" Sam Hearnton, Electronic Soundmaker & Computer Music, Mar 1985, pp. 30—31
  27. "The French Connection" Mark Jenkins writing as Tony Mills, International Musician & Recording World, Mar 1985, pp. 76—77
  28. "The Synthetic Realism Of Jean-Michel Jarre" Richard Buskin, Sound On Sound, May 1990, pp. 24—28
  29. "Yards Ahead" Matthew Vosburgh, Music Technology, Nov 1986, pp. 52—55
  30. The Last Whole Earth Catalog 2000, pp. 330—331
  31. "Photo Archive I" Wendy Carlos
  32. "Bob Moog — RIP" Wendy Carlos


Deep dives




Service notes



5U: 900 Series (Moog) | Sequencer Complement | The evolution of the 900 Series

Controller keyboards: 900 Series (Moog) | System-100M | microKEY

Modular synthesisers: 100 Series (Behringer) | 900 Series (Behringer) | 900 Series (Moog) | A-100 | Concussor | Sequencer Complement | System-100M | The evolution of the 900 Series

Moog: 900 Series (Moog) | Bob Moog | Bode Frequency Shifter | Sequencer Complement | The evolution of the 900 Series