Korg MS-10


Korg MS-10 is an analogue synthesizer created by Korg in 1978. Unlike its bigger brother, the MS-20, the MS-10 only has one VCO. It is monophonic and has 32 keys.
The MS-10 is well known for its huge sounding electro bass sounds.

Architecture

Audio path

Oscillator

The MS-10 has one VCO with 4 waveforms: triangle, sawtooth, pulse, and white noise.

Filter

The MS-10 has the same "KORG35" 12dB/Oct low pass filter as the original MS-20. Resonance is adjustable but not voltage-controlled.
Originally, the filters used Korg's proprietary thick film IC. Later, the filters were redesigned to use off-the-shelf LM13600 OTAs.
A useful illustration of the Korg-35 filter in-circuit is shown here and some photographs illustrating the later LM13600 filter daughterboard are shown here. The tonal difference between the two is that the original Korg-35 filter has a slight amount of hiss which overdrives into the sound at high resonant settings. This causes the filter to have more of a "screaming" effect similar to it being used with a distortion pedal. The revised filter has most of this noise cleared up and is less aggressive sounding.

Output

There is a simple single transistor VCA. The amplitude of the VCA can be controlled by the envelope generator.

Modulation

Modulation generator

The MS-10 has one LFO, labelled "modulation generator". It has two controls and two outputs.
The shape control affects the pulse width and the shape of the sloped output. At midway, the pulse width is 50% and the output is a triangle wave. Both outputs are available through the patch panel and can be used for triggering the envelope generators – the pulse wave with a key held down, and the sloped without. The depth of LFO modulation of the VCO frequency and the filter cut-off can be controlled from knobs in the respective sections of the control panel.

Envelope

There is one envelope generator with controls for Hold, Attack, Decay, Sustain and Release.

Patching

Although the MS-10 has normalized connections, they can be modified with patch cables. This allows the LFO to modulate the pulse width of the VCO or the amplitude of the VCA. It also has a noise generator with white and pink noise outputs, CV in and out, and an external signal input.

Compatibility With Other Synths and Modules

The MS-10's VCO uses linear voltage control but note that oct/V scaling is available via judicious use of the "freq" CV input socket. A CV converter can also be used.

Notable users