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 ring modulator was invented by Frank A. Cowan in 1934 and patented in 1935 as an improvement on the invention of Clyde R. Keith at Bell Labs. The original application was in the field of analogue telephony for frequency-division multiplexing for carrying multiple voice signals over telephone cables. We're not totally sure what that means either, and if it sounds like we cut-and-pasted that blurb from Wikipedia, it's because we did. Anyway, ring modulators (also known as a "balanced modulators") date back to the earliest days of electronic music, and were one of the handful of ways audio signals could be radically manipulated back in the pre-synthesizer days of musique concrète, which is French for "bunch-of-weird-French-dudes-making-a-racket-with-tape-recorders-and-test-oscillators."

When two audio sources are inputted, the output contains only the sum and difference frequencies of the two signals, while removing common frequencies. The audio result is useful for creating sounds with inharmonic frequency content, which is useful for synthesizing bell and metallic sounds.

In order to facilitate processing a single input signal, ring modulators often include an onboard oscillator. VM Rackmode Ring Modulator's oscillator is not unlike a typical analog synthesizer oscillator, featuring range controls, and multiple waveforms. Its pitch can also be "played" using Voltage Modular CV signals, allowing for (somewhat) more musical exploits in the realm of ring mod madness.

Input Section

A ring modulator needs two input signals to do its magic; the Mode selector defines how the signals are combined.

Input L/R- This is where input signals are patched. These can be a standard stereo audio signal or two completely different mono signals.

Input Mode Switch-

  • VCO x (L/R)- Combines the onboard Voltage-Controlled Oscillator (VCO) with incoming left/right signal.

  • L x R- Combines the left and right signals of an incoming stereo audio signal. The Ring Modulator will have no affect on mono signals in L x R mode.

Squelch Section

Squelch Threshold and lamp- Allows fine-tuning of input level to prevent bleedthrough of the unprocessed signal to the processed signal. Thanks to the wonder of modern computers, bleedthrough is a far less of a concern than with analog hardware frequency shifters, but it's included to accurately replicate the original.

Turning the knob clockwise sets the input threshold higher until the input signal completely disappears. The lamp illuminates to indicate signal is passing.

Squelch Switch- Say that three times fast... enables and disables Squelch.

Voltage-Controlled Oscillator Section

The Voltage-Controlled Oscillator (VCO) signal is combined with the incoming audio signals when the Input Mode Switch is set to the VCO x (L/R) position.

Coarse- Sets the the VCO's overall coarse pitch range in standard organ footage settings of 32', 16', 8', 4', and 2'.

Fine- Allows fine-tuning of pitch by 1.25 octaves, up or down.

Waveform- Selects the VCO audio waveform. Available waveforms are sine, triangle, ramp, saw, and square. The LED flashes at the current frequency rate.

Freq Mod CV jack and attenuator- Sets the modulation depth applied to VCO pitch. Center position equals no modulation; turning clockwise applies positive mod, turning counterclockwise applies negative mod.

1V/Oct jack- Allows oscillator pitch control in standard semi-tones via CV.

Output jacks- The ring modulated output signal(s).