WMD Phase Displacement Oscillator MKII (PDO MKII)
Introducing the WMD Phase Displacement Oscillator (PDO). This
hybrid VCO has all the feel of an analog VCO but with the benefits
of digital waveshaping. The PDO will easily find a home in your
The PDO exists to utilize the phenomenon of Phase Modulation
(PM). This allows for the relative phase difference of its outputs
to be set or modulated, producing very interesting sounds. The
result is similar to Frequency Modulation (FM) but affects the
output to a greater degree without affecting the stability of the
initial frequency. This is where the "displacement" comes in.
When you use frequency stable phase displacement, you create
phase distortion which sounds like wavefolding and is very useful
for dynamic textures and powerful sounds.
PM has the same benefits of quadrature filters/sine wave
generators and greatly exceeds their capabilities at audio rate
modulations. PM is highly useful for for creating metallic and bell
tones and very controlled harmonic interactions.
Because PM affects the relative phase and not the frequency of
the waveform generated, the PDO can self modulate its PM inputs.
This creates complex harmonic signals that seem to vary in
frequency but are quite stable.
Phase Modulation is also quite powerful when using the PDO as an
LFO. Adjusting the relative phase of each output allows for very
precise modulation of other modules. Each output can have any of
the available waveforms simultaneously. There is a myriad of
modulation possible with the PDO!
- Analog Sawcore VCO
- Temperature Compensated
- Linear or Expo FM
- Calibrated 1V/Oct Input
- Hard Sync Input (LFO Reset)
- ~.0012Hz (14min) to >=10kHz
- Digital Waveshaper
- Four Separate Waveform Outputs
- Phase Modulation for Outputs 2,3,4
- Global Phase Input
- Invertible CV Inputs for Phase Mod
- Any waveform on any output
- 14 Bit Input, 12 bit Output
- 100kHz Sample Rate
- Channel Indicator LEDs
- Sum output of all channels
- Normaled Sum output
- Expand/Jack CV simultaneous
- 16HP, +85mA -45mA Power Draw
Controls and I/O
The Phase Displacement Oscillator's analog VCO core should feel
familiar and intuitive.
1V/Oct Input - Calibrated input for pitch
control. The VCO will track at least 5 octaves using this
Sync Input - Rising edge sawtooth reset/sync
input. Does not affect slope of sawtooth. Use as LFO reset
Coarse & Fine Knobs - Coarse knob adjusts
the frequency of the VCO throughout its full range. Use the Fine
knob to tune the oscillator within a 1/3 octave range.
FM - Jack for Frequency Modulation. Type is
selectable with switch between Exponential and Linear. Linear may
be DC or AC coupled with a rear jumper.
Phase Modulation Inputs (Φ)
Phase Inputs (ΦCV) - The PDO has three phase
inputs, one for each channel: 2, 3 and 4. These inputs can use any
type of signal. Each phase input has an attenuator.
Phase Offset (Φ) - These controls set the
relative phase of each channel, from 0 degrees to + or - 360
degrees (total of 720 degrees). This control is added to the ΦCV
input and acts as a bias level control when there is an input.
Global Phase Input (ΦCV234) - This jack sends
its signal to each phase input equally, allowing for a single
signal to globally control the phase offset of each channel.
Jack / Both / Mod Switch - This switch controls
routing of the CV signals for interfacing with the Triple Bipolar
VCA. Jack allows the front panel jack and attenuator through. Mod
allows just the input from the TBVCA through. Both sums both
signals going into the phase modulation circuitry.
Inv Switch - This is the master invert switch
for the sum of the Jack/Mod/Both and the Global phase input per
channel. It will invert all signals.
Out1 - Out4 - These are the outputs for each
channel, the current level is displayed at the top of the module by
a green LED.
Sum Output - This output takes all four of the
outputs and sums them together.
Sum Normaled Output - This output takes each
output (1-4) that do not have cables inserted and sums them
together. Use this if you want to remove an output from the
Staircase Output (SC Out) - This output jack is
the result of the relative phases of the three phase input channels
compared to the analog sawtooth waveform. It forms a staircase type
output (multiple square waves added together).
There are two expansions for the PDO.
Quad Anti Aliasing Filter - This 4HP expansion
module consists of four independent -24dB/octave Butterworth Low
Pass Filters. They all share a common frequency input and bias
knob. The QuadAAF independently filters each output from the PDO,
providing an anti-aliased (smoother) output. There is also a sum
output of all four filtered signals.
Triple Bipolar VCA - This 8 HP expansion module
contains three independent polarizing VCAs. This allows for Mod
mode to be used which will produce stable wavefolding without
patching. By applying envelopes and other signals, very dynamic
patches can be produced.
Other Notable Things
The Phase Displacement Oscillator is 16HP.
Current consumption is 85mA for the +12 rail; 45mA for the -12
The depth from the back of the panel is roughly 26mm.