Serge synthesizer

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Serge Modular
Serge Modulars in the rack

The Serge synthesizer (aka Serge Modular or Serge Modular Music System) is an analogue modular synthesizer system originally developed by Serge Tcherepnin, Rich Gold and Randy Cohen at CalArts in late 1972. The first 20 Serge systems (then called "Tcherepnins") were built in 1973 in Tcherepnin's home.[1] Tcherepnin was a professor at CalArts at the time, and desired to create something like the exclusively expensive Buchla modular synthesizers "for the people that would be both inexpensive and powerful."[2] After building prototypes, Tcherepnin went on to develop kits for students to affordably build their own modular synthesizer, production taking place unofficially on a second floor Calarts balcony. This led to Tcherepnin leaving CalArts in order to produce kits commercially, starting in 1974.[3] Commercial builds of Serge synthesizers are currently available from Sound Transform Systems (STS) in Hartland, Wisconsin, USA, while a number of others enterprises offer DIY versions.

After leaving CalArts, Serge had a small factory on Western Avenue in Hollywood. He relocated to a three-story Victorian house on Haight Street in 1980. While the synthesizers were inexpensive compared to Moog, Buchla, and other manufacturers, Serge Tcherepnin's emphasis was always on providing musicians with quality equipment.

Serge synthesizers have been used by composers such as Michael Stearns and Kevin Braheny (who owned a 15-panel system dubbed The Mighty Serge). Serge synthesizers are known for their flexibility, audio quality and relative compactness. Other well-known musicians using Serge synthesizers include Malcom Cecil, whose studio was used in Stevie Wonder albums; Gary Chang, movie composer; Roger Powell, keyboard player for Todd Rundgren; and John Adams, composer.


Originally, the module configuration for Serge systems could be selected by the user. 4U panels with module widths typically ranging from 1" to 3" (sometimes more in the case of sequencers), several modules could then be arranged on a 17-inch-wide panel (total of 16 inches of modules), resulting in a custom built panel. These were originally arranged by applying paper graphics to the metal panel, which became metal self-applied graphics in the early 1980s and finally graphics printed directly onto the metal panel.

In the early 1990s the business was transferred to Rex Probe who renamed it Sound Transform Systems (STS). A number of changes were made over the years including the end of systems being sold as kits and user selectable module arrangements. STS moved onto 17" pre-configured 'Shop' panels and then the half sized 'M-Class panel. These are smaller 8" panels, allowing a user more variety than the Shop Panels but less than custom. These panels come with a black 1" center panel for power distribution.

Early systems had custom graphics—or no graphics—depending upon the whims of the artist. Soon Serge adopted a series of geometric designs denoting signal types, input, outputs, and triggers. Colored 4 mm sockets were used for most connections - blue, black, and red jacks for (unipolar) control voltages, bipolar signals (NOT necessarily AC coupled) and pulse/gate signals respectively, although these were not rigidly enforced. Later, other colors were introduced, e.g. yellow for triggers. By keeping output impedances low, Serge largely avoided the need for screened cables. 3.5 mm sockets were used for some audio interfacing to the outside World.

Serge modules did not distinguish between audio signal and control voltage jacks, all signals were patched from module to module via banana patch cords. Banana cables are most flexible in electronic patching and offer quick patching with a secure connection, most banana jacks can be stacked as well. The banana leads supplied are 4 mm Pomona made heavy insulated in silicone cable. With a simple ground connection made between different units cross connection/modulation can be made between units.

One of the first Serge Modular synthesizer created became the machine used on the first Greenpeace anti-whaling expedition (1975) by William (Will) Jackson, to approximate whale sounds and broadcast them to whales in the open Pacific. (A photo of this can be found in the Vancouver Sun newspaper archives May 1975.)


1st generation modules (1972)[edit]

The first generation of modules consisted of:

  • Dual voltage processor
  • Dual audio mixer
  • Peak and trough
  • Triple bidirectional router
  • Triple waveshaper
  • Gate (VCA)
  • Ring modulator
  • Envelope generator (wired ASR)
  • Oscillator (VCO with waveshaper)
  • Dual negative slew
  • Dual positive slew
  • Triple comparator (plus Schmitt trigger)
  • Voltage controlled filter (2 pole state variable)
  • Send & Return (audio interface)
  • Programmer (4 stage controller, linkable for 8 / 12 stages))
  • Sequencer (10 step pulse only)
  • Multiple

The Negative and Positive Slews, were able to function as envelope followers, low pass filters, modulating waveforms, subharmonic generators, and audio oscillators. The Programmer served as the performance interface, being a manually controlled sequencer. It could be patched to the (pulse) sequencer - in some early systems they were hard-wired together. These systems were essentially DIY.

2nd generation modules (1974)[edit]

Serge set up SMMS in 1974 and set about expanding and upgrading the range. This second generation of modules included:

  • Smooth and stepped function generator
  • Noise generator (later incl. S&H)
  • Phase shifter
  • Preamp
  • Reverb (spring)
  • Analog shift register
  • Keyboard Envelope generator (VC ADSR)

He also upgraded the mixer, dual processor, Send & Return, Oscillator etc. The circuit boards could serve several roles, so for example the Smooth & Stepped board was also used in the Random Voltage Generator, the Dual VC Slope Generator, the Rate-Controlled S&H etc.

As well as working on the modular range Serge worked with others. He designed and built custom modules for Cecil and Margouleff's TONTO system (as used on several Stevie Wonder albums) and worked with Frank Eventoff on his Sonica and Rainmaker instruments.

3rd generation modules (1976)[edit]

Around 1976, Serge started to replace some of his old designs with a new generation of state-of-the-art designs, pioneered highly accurate 1V/Oct oscillators and high dynamic range VCAs (voltage controlled amplifiers) that enabled a new filter technology with low-noise and equal power multi-channel panning. A new panel graphics style was also introduced, replacing the geometric designs with a simpler layout.

In addition to fully featured standard synthesis modules such as voltage controlled oscillators, filters, and envelope generators, the Serge system includes esoteric audio signal processors such as a Wave Multiplier, a multipurpose slew / envelope module and a very flexible touch-sensitive keyboard controller combined with a 16-stage analogue sequencer, known as the TKB. The new modules included:

  • Quad VCA
  • Universal Equal Power Audio Panner
  • PCO (high quality VCO)
  • NTO (PCO plus waveshaping, FM, etc.)
  • Variable bandwidth VCF
  • Variable slope VCF
  • Variable Q VCF (also extended range VCF)
  • Wave multipliers
  • Dual universal slope generator / Dual transient generator
  • Touch activated keyboard sequencer (TKB)
  • Extended ADSR
  • Pitch and envelope follower (Gentle Electric board on Serge panels)

He also extended the range of mixers and CV processors. Many of the circuit boards could by used in a variety of ways, and an exhaustive list of modules would be difficult to compile. Filter banks were made in small numbers, but it is uncertain if any hex panners were ever built. All the filters were 2 pole state variable.

While some earlier modules remained in production, the new modules replaced many of the older modules. These new designs remain at the heart of Serge Modular systems to the present day.

4th generation modules (1979)[edit]

Around 1979, a fourth generation of modules started to appear, complimenting the 1976 modules and replacing some earlier modules. The current Serge panel graphics style also appeared around this time. The new modules included:

  • Active processor
  • Resonant equalizer
  • 4//6/7/8 step sequencer
  • Divide/n comparator, dual comparator, Schmitt trigger
  • Wilson Analog Delay
  • Balanced modulator
  • Quantizer
  • Frequency shifter
  • Quadrature oscillator
  • Dual VCA
  • Envelope follower / preamp
  • N voice controller

Also, new electronics were designed for the audio mixer/processor/scaling/buffering modules and the VCA/panners, and the "paper face" panel graphics were replaced with metallized plastic film. Throughout this period, systems were available built or as kits - boards supplied pre-built and tested but you wire the panels up yourself. In1979, Serge offered a standard module configuration - the "System 79".

The N voice controller was a polyphonic interface which worked with a modified Casio keyboard. Sadly it appeared around 1982, just before MIDI.

5th generation modules (early 1990s)[edit]

The 1980s were not good times for modular synthesizer manufacturers, and no further modules appeared after 1983. In the early 1990s, Sound Transform Systems took over the range and added a few of their own designs to the range. These included:

  • Pulse Divider
  • Boolean Logic
  • Audio Mixer (with Phase Switch)
  • Balanced output module (on rear of panels)
  • MIDI CV (short lived)

They also introduced new variations on existing modules such as the VC Timegen Osc/clock/dual VC clock, and were able to use better quality parts and quality control (affordable component quality improved massively through the 1980s, especially good quality, cheap potentiometers).

There is very little information about early Serge power supplies, but Serge soon settled upon commercial Power One supplies set for +/-12v. Some first generation modules also required a +6v supply, initially provided by a 6v regulator on the supply but as these modules became fewer the regulators were mounted near the modules before dying out completely around 1980. The n-voice controller was unique in requiring a supply with an additional 5v rail. At some point, Condor supplies were used instead - these were almost identical to Power One supplies. Early supplies used a 4 pin Cinch Jones type connector, but sometime in the mid/late 1970s these were superseded by 5 pin XLRs. Power distribution in Serge panels were never as good as it perhaps should have been, but gradual improvements were made - distribution modules being introduced in the mid 1970s and the STS black panel for m-modules in recent times.


Originally Serge panels had all possible holes punched, and the panel labels covered over unused holes. While this was very versatile and allowed for upgrading or changing panels, it could look a bit scruffy. STS introduced graphics directly onto their panels, sacrificing some versatility for a more solid, professional look. They also introduced a range of standard "shop panel" configurations. More recently, STS changed to smaller M modules, where two narrower pre-configured panels fit each side of a center power modules.

Serge Modular's 40th anniversary was celebrated recently. The 1973 Triple Waveshaper remains the oldest module still in production by STS, now as part of the Wave Processor M-Module. Other early modules are available from other sources.

The 21st century has seen the rise of independent builders making printed circuit boards, kits, and finished panels available to the musician at prices that reflect the original spirit that Serge Tcherepnin brought to the field back in the 1970s. These builders are sending royalties back to Tcherepnin for each module or panel sold. Ken Stone was the first to open these floodgates and makes many of the PC boards available for purchase. Sometimes the circuitry has been redesigned to reflect available parts as well as optimizing circuit flow. He also makes his own compatible designs available as well as the designs of others.


  1. ^ Vail 2000, p. 150
  2. ^ Vail 2000, p. 149
  3. ^ Vail 2000, p. 151

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