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 idea of a voltage-controlled amplifier (VCA) is that an audio or control signal is patched to its input, and externally controlled voltage controlled via the Control Inputs jacks. This is useful for turning audio or control signals on or off, applying envelope volume curves to sounds, regulating the amount of modulation signals applied to audio signals, and more. A simple analogy would be to think of a water faucet, with the control voltage affecting how much the faucet is opened.

Inputs, Outputs, and Controls

Linear (Lin.)/Exponential (Exp.)- Selects the "curve" of the amplifier's response as the input CV rises from 0 to 5V. Lin. or linear response curve is equally proportional across the voltage input range, whereas Exp. or exponential curve is closer to how the human ear perceives volume. You'll likely want to use the Lin. setting for modulation or control voltage situations, and use the Exp. setting when an envelope generator is used to control an audio signal with the amplifier. Or just use whatever sounds best, we won't tell.

Fixed Control voltage- Adds up to 5V of gain. This works in addition to incoming and Control Inputs jack voltages. It's useful for manually "opening" the amplifier for drones.

Control Inputs jacks- Control signal inputs are patched in here. These have no attenuators and are "wide open" all the time - typically these would be used to patch an envelope generator. All three jacks are the same, and when more than one is used, incoming voltages are summed.

Signal Inputs jacks- Use this jack to patch in audio or control signals to be controlled by the VCA. Both inputs are summed.

Signal Outputs jacks- These carry the CV-modified version of input signals.