EVOC 20 PolySynth Synthesis Section Parameters

The EVOC 20 PolySynth is equipped with a polyphonic synthesizer. It is capable of accepting MIDI note input. The parameters of the Synthesis section are described below.

Figure. Synthesis section parameters.

EVOC 20 PolySynth Oscillator Parameters

The EVOC 20 PolySynth has two oscillators, which you can switch between Dual mode and FM mode:

Figure. Oscillator parameters.
  • Dual mode: Each oscillator allows you to choose a digital waveform.
  • FM mode: Oscillator 1 generates a sine wave. The frequency, or pitch, of Oscillator 1 is modulated by Oscillator 2 (for information about FM synthesis, see Frequency Modulation (FM) Synthesis). This leads to a number of different tones and harmonics becoming audible. Oscillator 2 can use any of the digital waveforms.

Each mode subtly changes the parameters shown in the Oscillator section.

The Synthesis section also incorporates a noise generator, which can add a further color to your sound. See the following for information on Dual mode, FM mode, and Noise generator mode:

Dual Mode EVOC 20 PolySynth Oscillator Parameters

FM Mode EVOC 20 PolySynth Oscillator Parameters

EVOC 20 PolySynth Noise Generator Parameters

Common EVOC 20 PolySynth Oscillator Parameters

This section describes parameters common to both Dual and FM modes.

  • 16', 8', 4' value buttons: Click to select the octave range for Oscillator 1. 16' (16 feet) is the lowest, and 4' the highest setting. The use of the term feet to determine octaves comes from the measurements of organ pipe lengths. The longer (and wider) the pipe, the deeper the tone.
  • Wave 1 and Wave 2 fields: Vertically drag the numerical value beside the Wave 1 and Wave 2 labels to select the waveform type for Oscillators 1 and 2, respectively. The EVOC 20 PolySynth features 50 single-cycle digital waveforms with different sonic characteristics.

Dual Mode EVOC 20 PolySynth Oscillator Parameters

In Dual mode, each oscillator can use any of 50 digital waveforms.

Figure. Dual Mode Oscillator parameters.
  • Semi field: Adjusts the tuning of Oscillator 2 in semitone steps.
  • Detune field: Fine-tunes both oscillators in cents. 100 cents equals a semitone step.
  • Balance slider: Sets the level balance between the two oscillator signals.

FM Mode EVOC 20 PolySynth Oscillator Parameters

When in FM mode, Oscillator 1 generates a sine wave. The Wave 1 parameter has no effect in this mode.

Figure. FM Mode Oscilator parameters.
  • “Ratio c(oarse)” field: Adjusts the frequency ratio between Oscillator 2 and Oscillator 1 in semitone steps.
  • “Ratio f(ine)” field: Adjusts the frequency ratio between Oscillator 2 and Oscillator 1 in cents.
  • FM Int slider: Determines the intensity of modulation. Higher values result in a more complex waveform with more overtones.

EVOC 20 PolySynth Noise Generator Parameters

The noise generator provides a further sound source that can be used alongside the two oscillators.

Figure. Noise Generator parameters.

Important: The noise generator in the Oscillator section is independent of the noise generator in the U/V Detection area. For further information about voiced and unvoiced signals, see EVOC 20 PolySynth (U/V) Detection Parameters.

  • Level knob: Controls the amount of noise added to the signals of the two oscillators.
  • Color knob: Controls the timbre of the noise signal. At the full-left position, the noise generator creates pure white noise. At the full-right position, you hear blue noise (high-passed noise). White noise has always been used to create wind and rain sound effects. It has the same energy in each frequency interval. Blue noise sounds brighter, because its bass portion is suppressed by a highpass filter.

    Tip: Set Color to the full-right position and Level to a very low value to achieve a more lively and fresh synthesis signal.

EVOC 20 PolySynth Tuning and Pitch Parameters

The parameters at the lower left of the interface are used to control the overall tuning and other pitch-related aspects of the EVOC 20 PolySynth sound.

Figure. Tuning and Pitch parameters.
  • Analog knob: Simulates the instability of analog circuitry found in vintage vocoders by randomly altering the pitch of each note. This behavior is much like that of polyphonic analog synthesizers. The Analog knob controls the intensity of this random detuning.
  • Tune field: Defines the overall tuning of the EVOC 20 PolySynth, in cents.
  • Glide knob: Determines the time it takes for the pitch to slide from one note to another—portamento. (For information about mono and legato, see EVOC 20 PolySynth Global Parameters.)
  • Bend Range field: Determines the pitch bend modulation range, in semitone steps.

EVOC 20 PolySynth Filter Parameters

The EVOC 20 PolySynth synthesis section has a simple lowpass filter. The filter is used for rough signal shaping, before the signal is more precisely shaped by the individual bands of the Formant Filter banks.

Figure. Filter parameters.
  • Cutoff knob: Sets the cutoff frequency of the lowpass filter. As you turn this knob to the left, an increasing number of high frequencies are removed from the synthesizer signal.
  • Resonance knob: Boosts or cuts the signal portion that surrounds the frequency defined by the Cutoff knob.

    Tip: Set cutoff as high as possible, and add a little resonance to achieve a nice, brilliant high-end.

EVOC 20 PolySynth Envelope Parameters

The EVOC 20 PolySynth features a simple Attack/Release envelope generator, which is used to control the level of the oscillators over time.

Figure. Envelope parameters.
  • Attack slider: Determines the amount of time it takes for the oscillators to reach their maximum level.
  • Release slider: Determines the amount of time it takes for the oscillators to reach their minimum level, after the keys have been released.

EVOC 20 PolySynth Global Parameters

The parameters at the top left of the interface determine the keyboard mode and number of voices used by the EVOC 20 PolySynth.

Figure. Global parameters.
  • Poly button/Voices field: When Poly is selected, the maximum number of Voices can be set in the numeric field.
  • Mono/Legato buttons: When Mono or Legato is selected, the EVOC 20 PolySynth is monophonic, and uses a single voice.
    • In Legato mode, Glide (see EVOC 20 PolySynth Tuning and Pitch Parameters) is only active on tied notes. Envelopes are not retriggered when tied notes are played (single trigger).

    • In Mono mode, Glide is always active and the envelopes are retriggered by every note played (multi trigger).

  • Unison button: Enables or disables Unison mode.
    • In Unison/Poly mode—where both the Unison and Poly buttons are active—each EVOC 20 PolySynth voice is doubled, which cuts polyphony in half (to a maximum of 8 voices, shown in the Voices field). The doubled voices are detuned by the amount defined with the Analog knob.

    • In Unison/Mono mode—where both the Unison and Mono or Legato buttons are active—up to 16 voices can be stacked and played monophonically. The Voices field displays the number of stacked voices that will be heard.

    Important: Stacking voices in Unison/Mono mode significantly increases the EVOC 20 PolySynth’s output volume. To avoid overloading the instrument channel strip output, you should initially set a low Level slider value and gradually bring it up (see EVOC 20 PolySynth Output Parameters).