VM2500 Blank Panel Module 1001 VM2500 Dual Envelope Generator Module 1003 VM2500 Oscillator Module 1004-P VM2500 Oscillator Module 1004-R VM2500 Oscillator Module 1004-T VM2500 Modamp Module 1005 VM2500 Filtamp Module 1006 VM2500 Dual Noise/Random Voltage Generator Module 1016 VM2500 Oscilloscope Module 1019 VM2500 Dual Oscillator Module 1023 VM2500 Dual Reverberator Module 1025 VM2500 Preset Voltage Module 1026 VM2500 Clocked Sequential Control Module 1027 VM2500 Dual Envelope Generator Module 1033 VM2500 Sample & Hold Module 1036 VM2500 Triple VCA Module 1042 VM2500 Synthesizer Voice Module 1045 VM2500 Quad Envelope Generator Module 1046 VM2500 Multimode Filter Resonator Module 1047 VM2500 Mix-Sequencer Module 1050 VM2500 Dual Four-Channel Mixer Module 1051 VM901 Voltage Controlled Oscillator VM902 Amplifier VM903 Random Signal Generator VM905 Reverb VM907A Fixed Filter Bank VM911-A Dual Trigger Delay VM912 Envelope Follower VM921 Voltage Controlled Oscillator VM923 Filters/Noise VM927 Multiple VM958 Keyboard/VCO Interface VM960 Sequencer VM962 Sequential Switch VM984 Four-Channel Matrix Mixer VM995 Attenuators VM914 Fixed Filter Bank VM928 Sample Hold VM1630 Frequency Shifter VM901ABBB Voltage Controlled Oscillator VM904A/B/C Filters VM911 Envelope Generator VM921ABBB Oscillator Bank VM Rackmode 10 Band Graphic EQ VM Rackmode 12 Stage Phaser VM Rackmode 3 Band Parametric EQ VM Rackmode Poly Vocal Source Oscillator VM Rackmode Ring Modulator VM Rackmode String Filter VM Rackmode Vocal Source Oscillator VM Rackmode Frequency Shifter VM Rackmode 16 Channel Vocoder VM Miniverse A-440 VM Miniverse Contour VM Miniverse Filter VM Miniverse Glide VM Miniverse Mixer VM Miniverse Noise VM Miniverse Oscillator VM Miniverse Poly Contour VM Miniverse Poly Filter VM Miniverse Poly Glide VM Miniverse Poly Mixer VM Miniverse Poly Oscillator VM Miniverse Poly VCA VM Miniverse VCA

The VM921 is a full-function oscillator module. It can be used in the audio range, or as a low-frequency modulation source.

Inputs, Outputs, and Controls

Scale- Sets the Frequency knob range to +/- 12 or +/- 6 semitones.

Coarse Range- Sets the coarse frequency range to sub-audio or standard audio range. Use the Sub-Audio setting when using VM921 as low-frequency modulation source; use the Audio setting when using as standard audio source.

Frequency- Continuously sets the base oscillator frequency range to +/- 12 or +/- 6 semitones depending on the Scale switch setting.

Range- Sets the base oscillator frequency in standard organ-style footage increments.

Waveform Volume- Sets the volume of the sine, triangle, square, ramp, and pulse waves in the master output. These do not affect volume of the individual wave out jacks.

Rectangular Width (Pulse Width) and Width Control jacks- Sets the width or "duty-cycle" of the rectangular (aka, pulse) wave ( the waveform on bottom right of the panel). It has no effect on any other waveform. Its default setting of 50% outputs a perfect square wave, rich in odd-order harmonics. Moving the knob left or right narrows its width as well as the thickness of sound until it almost disappears at its extremes.

The Width Control In jacks allow CV control of the width of the rectangular (pulse) wave. Both jacks are the same; their input voltages will be summed.

Clamping Point and Clamp Trig. jack- This is commonly known as oscillator sync. Sending a trigger or gate voltage to the Clamp Trig. jack restarts the wave from a point defined by the Clamping Point knob, from 0% to 100% of its cycle. (Incidentally, my family used to vacation at Clamping Point Knob in rural Maine in the 70s, but that's not important right now).

The V input is sensitive to rising edges passing through a +1V threshold. The S input is sensitive to falling edges passing through +1V. This reproduces the logic of S-trigger action without the headache.

Aux. Out. Waveform and Aux. Out. Level- Since all of the waveforms are concurrently available at the bottom jacks, these acts as convenient selectable wave outs with a dedicated volume knob. The right output jack signal is normal, and the left output jack signal is inverted. This section's settings have no effect on the dedicated wave out jacks at the bottom of the module.

Frequency Control Input jacks- Accepts a 1V/oct CV input for pitch or modulation. Typically this would come from the Pitch jack in the IO Panel CV Out section, a sequencer CV out, or a mod source. All three mod input jacks are the same and their CV's are summed.

These mod inputs are exponential, that is, for a given mod input voltage, the mod amount increases as frequency increases. For example, if the base frequency is 1000 Hz, and a bipolar wave is applied to the mod CV input, the frequency falls to 500 Hz and rises to 2000 Hz. Because audio frequencies are inherently exponential in nature, the resulting frequency rises and falls exactly one octave.

Sine/Triangular/Sawtooth/Rectangular output jacks- Output jacks for all oscillator waves. These can be used simultaneously, or in any combination. These are always at full amplitude.