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Tuesday, August 3rd, 2021 09:56 am

Synth Glossary

Frequency Modulation (FM):
Frequency modulation allows the output of one oscillator to drive the frequency of another oscillator. It can generate very complex sounds from very simple waveforms and is the basis of the Yamaha DX range of synthisizers and OPL range of synthesizer chips (used in Adlib and most other soundcards)....


The MC202 is a sequencer and simple monophonic synth with 32 buttons arranged like a small keyboard (F-C). The monosynth is similar to the SH-101. The VCO is based around the ever-so-popular Curtis 3340 chip and features a slider switch for octave (2', 4', 8', 16'), a slider for pulse width, and one for modulation (LFO) amount. The VCO outputs a square/pulse wave, a sawtooth wave, and a sub-oscillator which are mixed together in the "Source Mixer" section. The sub-oscillator is switchable between a square wave 1 octave down, a square wave 2 octaves down, and a pulse wave 3 octaves down. There are knobs which control fine tune and portamento. The VCF section has a slider for cutoff frequency and resonance. There is a slider for each of its control sources: envelope, LFO, and keyboard. The VCA can be controlled by a simple gate or the Envelope. The envelope is an ADSR with a slider for each stage.

The sequencer is quite powerful for its time. The MC-202 features a large (for the time) LCD display, upon which all the sequencing editing is displayed. The two available sequences can be played simultaneously using the CV/gate outputs to control another sequencer. The sequences can have a combined total of 2729 events. Sequences can be entered in real time via the pushbutton keyboard or via another keyboard using the CV/gate inputs. This feature has a negative side, though. Since all incoming CV/gate signals are routed through the microprocessor, there is a bit of a lag when the MC-202 is played by a another keyboard or a MIDI-to-CV device. The Sequences can also be programmed using step-time, setting a separate pitch and duration for each note. Also programmable in a sequence is accent and portamento. Accent works the same as in the TB-303, with an accent amount knob that can be adjusted in real time as the sequence is playing. The speed of the sequence is also controlled by a knob. The back panel has a sync input and two sync outputs, a tape interface for saving and loading sequences, CV/gate inputs and two CV/gate outputs (one for each sequence), a headphone jack, and a main output jack.

The MC-202 came out at a time when the synthesizer market was just starting to impliment MIDI. After MIDI became an accepted standard, sequencers such as the MC-202, using the old-style CV/gate interface, quickly lost popularity and died away.

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