Korg Sigma

Korg Sigma Image

The Sigma is an interesting bi-timbric synthesizer consisting of two sections: a genuine analog "Synthe" and a Preset "Instrument" section. All together, there are 19 presets on it that give a variety of sounds. There are 11 presets for the "Instrument" section which include fuzz guitar, electric bass, clavi, string, flute, double reed, trumpet, hammered percussion, etc. And there are 8 presets for the "Synthe" section that give variable waveforms (square, pulse, sawtooth) in different pitch ranges (from 32' to 4'). Each preset has its own rotary control to vary its sounds. The Sigma is also unique for its ability to combine the synth and instrument sections for a nicer, layered synth sound or effect. While the synth section is nice, the instrumental sounds (tuba, trumpet, strings, guitar, etc.) are pretty darn bad, and only get interesting when mixed with the "Synthe" section sounds.

Cool joysticks add multi-dimensional control. Use one to control pitch, noise and vibrato and use the second joystick to edit the low-pass and hi-pass voltage controlled filters! There is also an "Effect" section which is for Vibrato, Portamento, Sample and Hold, Noise, Key Hold, Multiple Trigger and Ring Modulator (each with it's own rotary control to vary it's sound). Even though it has a switch labelled "Ring Mod," it's actually a cross-mod. It lets you cross modulate between the instrument and Synth sections.

Ultimately, however, a basic design, limited edit-ability and a pure lack of memory and MIDI leave the Sigma far behind on the evolutionary scale (although it does let you play a quarter-tone scale). The Sigma has a metal music stand that slides out the back to hold your sheet music suggesting it may have been aimed at hobbyists, though it has been used by Jean Michel Jarre, Rick Wakeman and Keith Emerson. One user describes the Sigma as, "An absolutely terrible keyboard, that is utterly fantastic!"

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32 Visitor comments
w.t. salmela
January 21, 2014 @ 6:12 am
Sigma is an astounding lead synth, very expressive with dual joysticks and aftertouch. Had to sell mine (and ruin my greek Korgs collection) because I'm not a proper keyboard player.
It can however be controlled via MIDI with CV converter but it can lose some of it's unique behaving character this way - depending how you'll use it.

The sound is really funky and gritty, and can get huge with several presets engaged! You'll miss some programming options with this odd but tasty synth but there are something to experimenth with S&H and cross mod if you want more than just leads and basses.
July 14, 2013 @ 12:17 pm
Different territory Black Box :)
very very underrated organism. would like to see kid's faces when they encounter this box in year 2033
March 27, 2013 @ 9:47 pm
Excellent for leads, Huge bass: Anyone looking for pure analogue sonic power will be in love with this one, great pitch bender, awesome filters, almost every combination sounds awesome, really INSPIRING to create music! This thing is not shy, it actualy beggs to be in the front of the mix. you can put the two oscillator slightly out of tune and the results will be awesome!
I think that this were strange even for their time; BTW, i have two of these, I'm in Mexico, if you are interested :nosurprises777 at hotm . One of the best analogues ever, surely underrated
February 14, 2013 @ 6:24 pm
A very strange instrument design wise, but with a great cutting analog sound very close to the MS20. Sounds thicker than the sh-1000/2000, and has ringmodulator, high pass and low pass filter, multiple waveforms, and layering with the instrument section. Will rise in price for sure.
January 21, 2013 @ 8:10 am
Man this one is a weird little rascal. I mean what were the Korg engineers thinking when they created this thing? But it sounds great! In a Korg nasal kind of way. The Ins section isn’t that bad cause it’s just fixed settings of the Synth section. Every preset has a knob for only one parameter. There are 2 joysticks for pitch/mod and HP/LP-Filter + a Vibrato knob. The Keyboard has aftertouch assignable to Pitch (up/down) or Vibrato. And it has plenty of In and outs on the back for FilterFM, FilterCV, EG...Pure fun!. What do I miss? Control over resonance! Cause the filter is so cool. :)
VSE Rating


User Rating

Rated 4.44 (808 Votes)

  • Check Price
  • The link above will take you to an eBay search for this synth to see active listings. If you don't find it there, try looking in our forum marketplace or post a wanted classified.
  • Demos & Media
  • YouTube Thumbnail
    Korg Sigma
    by ikworgek

    Audio Clip 1 - Some demo sounds and effects created by the Sigma including effects, wind, modulation and synth sounds.

    Manual - Here is a link to the Sigma's manual. The manual is available as scanned JPG files.

    Brochure - PDF of 1980 Korg Brochure, submitted by Niels Kloes

  • Specifications
  • Polyphony - Monophonic (Bi-timbral: 2 different sounds at the same time)
  • Oscillators - Synth and String sections with a total of 18 VCO's. Sawtooth and Square waveforms along with PWM and noise are available in the "Synth" section.
  • LFO - Vibrato
  • Filter - 12dB/oct Low-pass and Hi-pass with 'Joystick' controller
  • VCA - Attack / Decay
  • Keyboard - 37 keys
  • Memory - None
  • Control - CV, Trigger
  • Date Produced - 1979
  • Resources & Credits
  • Images from Korg Product Brochure.

    Thanks to Orrin Anderson, Lee Matthews and Richard Easter for supplying some information.

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