44
Pulse Width modulation
Pulse Width Modulation (PWM) alters the
basic shape of the waveform by shifting its
internal structure over time, making some
areas narrower and others wider. This is
normally only heard with square waves, but
the Hydrasynth voice engine can apply PWM
to any of its 219 waveforms.
And there’s more! Hydrasynth takes PWM in
entirely new directions by providing not one,
but *three* types of PWM. Each has the same
parameters (with one exception as noted
below), but the results of each type can be
radically different!
PWM parameter Range
Description
Ratio
0.250-64.000 in
varying increments
How many times PWM happens in a single cycle.
Hold [SHIFT] to jump by whole numbers.
Depth
0-128 in
increments of 0.1
Controls harmonic range of PWM
Feedback
0-150%
Feeds the PWM output back into itself
Custom Edit
(PW-ASM only)
(access)
Press Control button 7 to access Warp points.
(See PW-ASM [Warp] section.)
Dry/Wet
0-100%
Mix raw wa PWM result; 100% = pure Mutant
PW-Orig
This is the “vintage” PWM used by many
analog polysynths in the ‘70s and ‘80s: a
waveform is fixed at its center and both of
its edges are moved to compress or expand
its width. The PWM source is often an LFO,
though an Envelope or other sources can yield
excellent results.
PW-Sqeez
This form of Pulse Width modulation grabs the
start and end points of the modulation and
then squeezes them to the right. It might help
to think of this as “time-warping” a waveform:
It makes the oscillator go slow at first and then
go fast, all in the space of a single cycle.
PW-ASM [Warp]
PW-ASM mode divides the selected waveform
into 8 sections that are framed by Warp
points. The values chosen for each Warp point
determine how warped each section of the
waveform can become.
Here’s an example of PW-ASM mode in action.
1. Start in Single mode with an initialized
patch (press [INIT] twice).
2. Access [OSC 1] and select the sine wave.
3. Access [MUTANT 1] and select PW-ASM
mode.
4. Set Mutant 1 Depth to 128.0 and Dry/
Wet to 100%.
5. Press Control button 7 to access Custom
Edit.
6. Hold a note and turn Control knob 2
slowly.
7. Listen and watch the display as Warp2
changes from 0 to 128 and back.
Note how the waveform is affected only
in one specific area (i.e., Warp point 2).
8. Repeat steps 6 and 7 with one or more
Warp points at various values.
9. Also try different settings for Ratio,
Feedback, and Dry/Wet. The sonic
potential is nearly limitless.
PW-ASM mode is actually a form of Frequency
Modulation (FM). It allows you to draw your
own modulator waveform by selecting
different values for each of the 8 Warp points.
Construct a slope, a valley, a mound, jagged
peaks, pseudo-random, etc.; your design will
become an FM source (i.e., the modulator).
Each Warp point can be a destination
in the Mod Matrix, so timbral changes
can be as subtle or wild as you like. For
example, use synced LFOs as mod
sources and various Warp points as
destinations.