Phantasmatic - Phase Distortion Oscillator

Like its older brother Prismatic, Phantasmatic is a phase distortion oscillator inspired by the Casio CZ series synthesizers of the 1980s. It uses Digital Controlled Waveform (DCW) synthesis to morph smoothly between different waveforms, creating a wide range of timbres from smooth to aggressively digital.

Unlike Prismatic, Phantasmatic uses double precision floating point arithmetic throughout its processing chain, and tries to minimise aliasing and quantisation noise. Where Prismatic had a "nastiness" control for switching off filtering and linear smoothing intended to tame the noise, Phantasmatic has a "niceness" control which switches on 2x oversampling for antialiasing.

What is Phase Distortion?

Unlike traditional analog oscillators that generate fixed waveforms, phase distortion synthesis warps the phase of a sine wave before it's looked up in a wavetable. By changing how the phase accumulator maps to the sine table, you can transform a pure sine wave into sawtooth, square, or complex intermediate shapes.

The DCW (Digital Controlled Waveform) parameter controls this warping, letting you sweep continuously from one waveform to another - like morphing from a bright sawtooth through a sine wave to a hollow square wave.

Controls

V/OCT IN Section

MONO jack - Monophonic V/Oct pitch input POLY jack - Polyphonic V/Oct pitch input (16 voices)

Both mono and poly oscillators run simultaneously. The mono output is always active, while poly output is only processed when a cable is connected to the POLY output jack.

PITCH ADJUST Section

SEMI knob - Pitch adjustment in semitones (-7 to +7) CENT knob - Fine pitch adjustment in cents (-100 to +100)

OCTAVE Section

Six buttons for octave transposition:

• LO - 4 octaves down
• 32 - 2 octaves down
• 16 - 1 octave down
• 8 - No transposition (default)
• 4 - 1 octave up
• 2 - 2 octaves up

FM Section

MONO jack - Monophonic FM input POLY jack - Polyphonic FM input AMT knob - FM modulation amount (0 to 1) LIN/EXP switch - FM mode selector

Linear FM (LIN): Classic frequency modulation where the FM signal directly modulates the oscillator's frequency increment. This produces traditional FM synthesis sounds, with more dramatic effects at lower pitches.

Exponential FM (EXP): The FM signal modulates the V/Oct pitch exponentially. At full FM amount with ±5V input, you get ±1 octave of pitch variation. This creates through-zero FM effects and generates harmonic sidebands.

TIMBRE Section

WAVE switch - Four-position synthesis mode selector:

1. SAW ← [SINE] → SQUARE Default mode. Morphs from sawtooth through sine to square wave.

   • Negative DCW: sawtooth-like timbres
   • Center (DCW = 0): pure sine wave
   • Positive DCW: square-like timbres

2. SQUARE ← [SAW] → SINE Morphs from square through sawtooth to sine wave.

   • Negative DCW: square-like timbres
   • Center: sawtooth-like timbre
   • Positive DCW: sine wave

3. SINE ← [SQUARE] → SAW Morphs from sine through square to sawtooth.

   • Negative DCW: sine wave
   • Center: square-like timbre
   • Positive DCW: sawtooth-like timbre

4. RESONANT Special mode with variable harmonic emphasis. The DCW control adjusts the frequency multiplier of a resonant oscillator that's amplitude-modulated by the main phase, creating sync-like timbres with controllable brightness.

   • Negative DCW: lower frequency multiplier (1/2-1x)
   • Center: 1x frequency multiplier
   • Positive DCW: higher frequency multiplier (1-4x)

DCW knob - Digital Controlled Waveform parameter (-1 to +1) Sets the base timbre for the oscillator. The exact effect depends on the selected WAVE mode (see above).

DCW MOD Section

MONO jack - Monophonic DCW modulation input POLY jack - Polyphonic DCW modulation input AMT knob - DCW modulation amount (-1 to +1)

DCW modulation lets you animate the timbre in real-time, typically with envelopes or LFOs. The modulation amount is bidirectional - negative values invert the modulation.

QUALITY Section

Niceness switch - turns 2x oversampling on and off.

OSC OUT Section

MONO jack - Monophonic oscillator output POLY jack - Polyphonic oscillator output (up to 16 voices)

Output range is approximately ±5V.