Analog Synthesis

Join us for a new synthesis class that will use of the Korg MS 20 as a tool to explain Analog Synthesis. Back in the day, educators used the MS 20 to teach synthesis in schools (see the educators version of the MS 20 pictured above). ROBOTSPEAk's Modular Synthesis teacher LX Rudis has created a scaled back synopsis that gets down and into the depths of understanding synthesis in this 3 hour class.

The MS 20 and its manual will be used as a general tool to help you understand synthesis. The ideas taught in this class will be universal  concepts that will apply to analog synthesis regardless of what you are using.



VCO [Voltage Controlled Oscillators]:

demonstration of the VCOs pitch range and tones they can produce.


the following waveforms will be demonstrated and possible uses will be explained:




pulse wave [2 settings]

pulse width variable control [VCO2]


two additional modules are accessed via VCO controls.  these will be demonstrated and explained:

white noise - used for wind and percussion sounds

ring modulator - used for some metallic and distortion effects.


demonstrate VCO modulation [pitch modulation]:

LFO modulation

Envelope 1 modulation

brief explanation of external modulation input 


demonstrate additional controls:

master tune




demonstrate complex tone shaping possible with 2 VCOs

brief discussion of external signal processing and how external signals are mixed into the ms20's signal flow.


VCF [Voltage Controlled Filters]:

demonstrate cutoff frequency for Low Pass filter

demonstrate cutoff frequency for High Pass filter

Resonance/Peak and how it affects both filters

brief explanation of harmonic series

demonstrate use of filters within context of harmonics

demonstrate Envelope 2 modulation

demonstrate LFO modulation

Brief description of External modulation of cutoff frequency


VCA [Voltage Controlled Amplifier]:

explain how EG2 controls VCA

briefly describe 'VCA2' on patch panel


EG1+2 [Envelope Generators]:

demonstrate time/level controls for both envelopes

demonstrate 'looping' trick for EG1

explain implementation of EG2-VCF hardwired patch

use MG, VCA2 and EG1 to create a 'delayed vibrato' effect.


MG [Modulation Generator or LFO]:

demonstrate frequency range of LFO

demonstrate variabe triangle waveshape

demonstrate variable duty cycle of pulse wave


Additional Modules:

briefly demonstrate Sample/Hold using LFO to clock noise for random effect.

explain unusual 'sample/drift' design of ms-20 S/H

revisit VCA2 and 'vibrato patch' above.  discuss use of VCA to control modulation.


Additional Controls:

demonstrate Control Wheel with VCO and/or VCF 

demonstrate Control Wheel used to lock VCA open.

briefly discuss other uses


demonstrate Momentary Button used to trigger synth

demonstrate Momentary Button used to control vibrato patch

briefly discuss other uses


ESP [External Signal Processor]:

demonstrate ESP controlling ms-20 pitch and envelopes.

demonstrate ESP being used to process drums or full mix.


remaining class time will be spent doing patching experiments with the ms-20 synths.