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Chapter 22 ES2 289
Tutorial Settings: PWM Start, PWM Slow, PWM Fast, and PWM Scaled
Topic: Slow and Fast Pulse Width Modulations with Oscillator 2
Pulse Width Modulation (PWM) is one of the most essential features of any
sophisticated analog synthesizer. Use this setting to manually control the pulse width
of a rectangular wave, set via the Wave control
Note: Avoid Drive and Distortion with PWM sounds.
• Select the “PWM Start” setting, and move the Wave control slowly back and forth
between the rectangular and the pulse wave symbols. Both are green. What you will
hear is a (manual) pulse width modulation.
• Select the “PWM Slow” setting. Here, LFO 1 controls the pulse width modulation
source, not your manual movements. The result should be quite similar.
• Raise the LFO 1 rate from its pre-set value of 0.230 to 4.400. The result is a classic, fast
PWM.
• In this, and the next step, the PWM shall be set so that it sounds slower in the lower
keyboard range, and faster in the upper range. This is desirable for many sounds,
such as synthetic strings. First, reduce the LFO 1 Rate to 3,800.
• Change the modulation intensity of the second router channel (target = LFO1 Rate,
Source = Kybd) to 0.46. This will alter the scaling of the PWM, making it sound faster
in the treble range. You can also hear this type of effect in the “PWM Scaled” setting.
Tutorial Settings: PWM 2 Osc and PWM Soft Strings
Topics: Pulse Width Modulation with Two Oscillators, PWM Strings
In order to make the sound fatter, add Oscillator 3, which can also be modulated in
pulse width. In fact, even the first oscillator can deliver PWM. In the “PWM 2 Osc”
setting, both oscillators are detuned in a relatively strong way. Develop your own
personalized PWM string sound, using this setting as your “base”.
• Adjust the Chorus intensity. You’ll probably choose higher values which make the
sound rather broad.
• Program Envelope 3 according to your taste. You should, at the very least, raise the
attack and release times. Define it to react to velocity, if you prefer. If you do not
intend to solely use the sound as a simple pad, a shorter Decay Time and a lower
Sustain Level of about 80 to 90% may be more appropriate.
• Reduce the Cutoff Frequency and Resonance of Filter 1 to make the sound softer.
• Save the new setting.
• Compare the result with the “PWM 2 Osc” setting. You’ll hear that the sound has
undergone a remarkable evolution.
• Compare it to “PWM Soft Strings”, which was created as described above. You’ll
probably notice a few similarities.