Oscillator RA-1

Type: Module

Category: Source

Updated: Jan 11, 2020

Manufacturer: M*4

Contact Manufacturer


It is a relatively clean; less aliasing; audio rate oscillator. Basically it generates ramp waveforms. The waveform can be morphed with some internal parameters and the sound is varied for a ramp oscillator. It also has other outputs for the inverted version of generated ramp and for a pulse wave sub-oscillator.

The internal two-mode glide processor can help to reduce some space for a glide module and a sample of latency caused by chaining a module.

It's not a kind of "faithful emulation of ~." However, the control panel inspires a feeling of "playing sliders" or "tuning oscillators by ear."

*Updated and now with the internal glide processor! *Update 2, now Sub oscillator has clean sound!

Controls and I/O


  • Coarse Tune: Sets tuning of oscillator. The frequency of oscillator is calculated with sum of control voltages which includes CVs generated by tuning sliders and input signal from 1v/oct., FM1, FM2, and FM3. The range of the slider itself is 0 ~ 5v. Default value is 1v and it's similar to 16'.
  • Fine Tune: Adjusts tuning of oscillator with finer value. The range is ±0.5v, or ±0.5 octave. Default position is center and it indicates ±0v.
  • Pulse Width: Controls the width of waveforms. Even the name Pulse Width, all waveforms generated by the oscillator (including ramp and inverted) can be affected. The range is 1% ~ 99%. Default value is 50%.
  • FM1~3: Controls the volume of incoming CV signal for frequency modulation. Each input has different attenuator and if sliders are 100% position, FM1 inputs incoming signal unchanged, FM2 inputs the signal at the level of 25% and FM3 is 5%.
  • PWM: Controls the volume of CV signal for pulse width modulation.


  • Edge: Adds some metalic overtones to the waveform.
  • Edge CV Input Volume: Adjusts the volume of the input signal between 0% ~ 100%.
  • Soft: Morphs the waveform to skewed triangle-like form.
  • Soft CV Input Volume: Adjusts the volume of the input signal between 0% ~ 100%.
  • Glide: Adjusts glide time for internal glide processor. To switch the glide processor off, simply set the glide time 0 ms (hard left).


  • Ramp Morph on/off: If the switch is on, ramp oscillator is affected by Edge and Soft morph controller.
  • Sub Morph on/off: If the switch is on, sub oscillator is affected by Edge and Soft morph controller.
  • HQ on/off: Changes quality of output sounds by enabling/disabling anti-aliasing processes. Some aliasing noises can be recognized at much higher pitch (around C7 or higher) even the HQ switch is on.
  • Sync Mode: Sync mode can be switched by the switch at the right hand of sync input. In mode 1, the phase of oscillator is reset at the source signal is in positive voltages. In mode 2, the phase is reset when the source signal crossed 0 volt.
  • Glide Mode: Internal glide processor has two modes. "Lin." means "linear" and the amount of time to reach target pitch will be varied with the distance between current and next pitch. "Con." means "constant". Regardless of the distance between current and next pitch, the amount of time to reach target pitch will be the same in constant mode.


  • Sync: Resets the phase of waveforms manually by pushing the button.


  • 1v/oct.: Inputs exponential pitch CV signal.
  • Sync: An input for hard sync. The behavior of oscillator sync can be changed by Sync Mode switch. *See the Switches section for the detail.
  • FM1~3: Inputs CV signal to modulate frequency of the oscillator. All FM inputs have exponential response and each input has different attenuator. *See the Sliders section for the detail.
  • PWM: Pulse width can be modulated with the signal input the PWM input jack.
  • Edge Modulation CV Input: Modulates Edge parameter of the generator.
  • Soft Modulation CV Input: Modulates Soft parameter of the generator.


  • Ramp: Main output of the module.
  • Inverted: Outputs inverted version of generated ramp waveforms.
  • Sub: Outputs the pulse waveform generated with sub-oscillator. The frequency of sub-oscillator is half of the ramp generator.

Title of Song

  • RA-1-Ramp---signal-test-2-HQ-off
  • RA-1-Ramp---signal-test-1
  • RA-1-Ramp---signal-test-2-HQ-on
  • RA-1 Sub - signal test 1_build18
  • RA-1 Sub - signal test 2 HQ on__build18
  • RA-1 Sub - signal test 2 HQ off__build18
  • RA-1 demo 3VCO Lead