by Eric Den Haan
This is a very brief explanation of the various controls on the Minimoog Voyager OS – a deceptively simple looking monophonic synthesizer modelled after the classic Minimoog Model D of the 1970’s.
The path of an audio signal through this synthesizer begins with the oscillator section in the middle of the control panel. There are three oscillators, each with a six-step octave control and a continuous waveform selector (triangle, sawtooth, square, or rectangle waveforms are available). Oscillator 1 is the master oscillator, controlling the tuning of oscillators 2 and 3. Oscillators 2 and 3 also have a frequency control for allowing further fine tuning of their pitches. In the lower left hand corner of the control panel, two more knobs can control the oscillators: a further fine tuning knob (+/- 2 semitones), and a glide rate, which controls the speed of glissandi when the the glide switch next to the keyboard is engaged.
The switches at the bottom of the oscillator section have the following functions:
1-2 Sync – Synchronizes oscillator 2 to oscillator 1.
3-1 FM – Oscillator 3 will perform linear frequency modulation on oscillator 1’s signal when this switch is engaged.
3 KB Cont – Selects whether oscillator 3 is controlled by the keyboard.
3 Freq – The frequency range of oscillator 3 (low or high)
These oscillators can be blended together using the mixer section, situated to the right of the oscillator section. There is also a control to blend in an external audio source, as well as a white noise generator which can be blended with the oscillators.
To the right of the mixer section lies the filter section. The first knob at the top controls the cutoff frequency. Anything above this frequency will be inaudible, anything below will be heard. The switch at the bottom determines whether the filter acts as a dual lowpass filter or a highpass/lowpass filter.
When in dual lowpass mode, the spacing knob can make the cutoff frequency different for the right and left channel. The resonance knob controls both lowpass filters in this mode.
When in highpass/lowpass mode, the spacing knob controls the distance between the highpass and lowpass filter’s frequencies. The resonance knob controls only the lowpass filter in this mode.
After the filter section comes the envelopes section. There are filter and volume envelopes, each with traditional ADSR controls in descending order. The filter envelope also has a control called “amount to filter” which determines how much the filter is modulated by the envelope. There is a also a switch in the bottom right of this section which allows the user to determine whether the envelopes are triggered by the keyboard or an external source.
The furthest left section of the Voyager holds two modulation busses and the LFO. Each modulation bus can receive one of six sources, and send to one of six destinations. They can be controlled by one of six parameters as well. At the bottom of each bus, there is a knob which controls the amount of modulation provided by each bus.
The LFO controls the speed and waveform of the modulation. The waveform can be either a triangle wave, square wave, or smooth and stepped sample and hold (a random, pulsating waveform)
There are traditional pitch and modulation wheels next to the keyboard, as well as a switch to turn the glide on, as well as a release switch which shortens the release times of the filter and volume envelopes.