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Sunday, January 21st, 2018 12:20 am

Synth Glossary

A modular synthesizer is one where the structure of the synthesizer isn't fixed. There are a variety of modules available which can be plugged into each other. Tradionally these modules were physical boxes, but they can now be emulated with software and patched with on-screen cables....


Korg MS-20
"The MS-20 [the most popular of the MS series] was designed in Japan by Messrs. Mieda (who designed Korg's first keyboard product, and organ back in 1967 and went on to become head of Korg engineering) and Mori (who moved on to a special engineering group working working on new synthesis techniques, after leading the design teams on the CX-3, Mono/Poly and Poly 800). The idea behind the MS-20 was to produce a scaled down version of Korg's bulky PS series of polyphonic patch bay synths produced in the same year. At this time, there were plenty of good small mono synths on the market, but few boasting patch bays like you'd find on the big boys from Moog, Moog, or indeed Korg. (The beauty of a patch bay is that you can physically connect 'modules' of the instrument, such as the filter, the oscillator or the LFO, in the precise way you want rather than having to stick to a predefined layout and routing.) "The MS-20 stands out physically, with its steeply sloping control panel (though it doesn't collapse like that of the Minimoog) and tiny, 'professional-looking' schematics and labels dotted about on its battleship-gray metal casing [with a 3-octave 37-note (C- C) keyboard and 35-socket patch bay]. High-quality components were used; the control knobs [a total of 36] offer the sort of precision that only money can buy. Compact compared to the PS series, the MS-20 is still an awkward shape, with the lone control wheel tucked down below the botttom C on the final inch's worth of ledge. The design has definite pose value, but once cased, an MS-20 does make a hefty package to cart around.

"This is a dual-oscillator synth. Each Voltage Controlled Oscillator, or VCO, has its own marked-out area of panel, allowing you to set up different waveforms and different pitches for each. VCO1 offers triangle, sawtooth and variable-pulse waveforms, as well as white noise (for steam sounds, explosions, breath of wind sounds, etc.). Pitch can be varied over four octaves. VCO2 offers sawtooth, set [non-variable] square and narrow pulse waveforms, and a ring modulator. The ring modulator setting harnesses both oscillators to produce those hard-edged bell and gong-like sounds used in the 1990s by artists like The Shamen. VCO2 is also scaled one octave higher. To the right, there is a small mixing panel with separate control knobs for VCO1 and VCO2 levels. Pitch can be modulated by the LFO or one of the two envelope generators. "Already this has the makings of a powerful system: independent waveforms, ring modulation, noise, independent balance. But the MS-20 also offers separate low- and high-pass filtering, each with its own 'peak' (resonance) controls. Filtering can be modulated by the modulation generator (LFO) for filter vibrato or wah effects and shaped over time using one of the envelope generators. "The modulation generator itself offers a number of knob-controlled waveshapes, plus full control over mod speed. There are two envelope generators [which can be triggered via the keyboard or a manual trigger button]: EG1, which is internally routed to the oscillator, featuring delay [to delay the triggering of the envelope], attack and release time; EG2, which is generally used for shaping both VCA and VCF and offers attack, decay, sustain, release and hold. [Both envelopes are available in the patch bay at positive and negative values.]

"Along with Portamento (a lone knob governing time - i.e., speed) and master tune, these are the MS-20's basic sound-generating tools. Features under know control are simple and direct. If you want to carry out more advanced maneuvers, then you can reel out sundry lengths of spaghetti and start customizing and patching. You can, for instance, reverse the polarity of the EGs; patch in a footpedal to control the filter cutoff in real time; make use of a sample and hold circuit (for crazy, random squeaks and squaks); or harness the (darker) pink noise, either as a source or a modulation signal. "You can also get really adventurous and use the MS-20's own pitch-to-voltage converter and External Signal Processor inputs to trigger the instrument from a guitar or even a microphone, for a form of guitar synthesis or vocoding. You can also fire off an MS-20 sound triggered from, say, a snare drum on tape. The flexibility this offers, both internally and externally, is almost unlimited -- providing you have the time, the inclination and a modicum of knowledge to exploit it. If you are lucky enough to find one, the MS-20 manual is extremely concise and helpful on the subject of patching." "What does an MS-20 sound like? The 12dB/octave filtering (using custom-designed Korg filters) may not furnish the raw power of a Curtis chip, but the high/low (and even bandpass, from the patchbay) filtering options, plus ring modulation, definitely give the instrument bags of character, in the hard-edged, electronic way that is totally in keeping with its vaguely military appearance. In pure sound terms, Korg Japan advises that the signal-to-noise ration does leave a little to be desired, so you might want to gate out residual white noise inherent in the circuitry. the problem may be particularly apparent on the MS-20's single-oscillator baby brother, the MS-10, whose white noise generator delivers a sound more like breakup than noise anyway.

"A point of interest is that Korg UK's Phil MacDonald sampled his own MS-20 for many of the 'spitty' drum noises on Korg's i-series workstations. Phil's [MS-20] is one of the extremely rare 'Big MS-20,' giant-scale versions of the instrument made by hand for a select number of star endorsees [including Keith Emerson, YMO and Kitaro] and music colleges. Only around 20 of these instruments were ever produced." "Though relatively reliable, the MS-20 can use standard transistors and op amps, rendering spares not a problem, theoretically. When examining a second-hand unit, it might be advisable to check the state of the jack field (sockets can rust, among other things), though even these can be replaced without too much heartache. A number of accessories were produced, including cut-to-length patchcords [only two were provided when you bought the MS-20 new]; the MS-01 foot controller, with which you can operate parameters like filter cutoff in real time; and the SQ-10 analog sequencer, which allows you to program a sequence of up to 24 notes with individual pitch, timing and tone color. (Since the unit can also be used to store MS-20 sounds, it makes a useful addition to your system.)

"Interfacing the MS-20 with the outside world was always a bit of a problem, largely because Korg adopted the Hz-to-voltage system rather than the more common on volt- per-octave standard used by the other synths at the time. Korg's stout devense was the Hz-to-voltage gives you greater oscillator (pitch) stability. Track down an MS-20 interface, which converts to one volt-per-octave, or more likely a third-party equivalent, if you feel the burning need to interface with other synths and sequencers."

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