8

Table Of Contents
Chapter 20 ES2 207
Sync
The rectangular and sawtooth waveforms also feature a Sync option. In this mode, the
frequency of Oscillator 2 (or 3, respectively) is synchronized to the frequency of
Oscillator 1.
This does not mean that their frequency controls are simply disabled. They still oscillate
at their selected frequencies, but every time that Oscillator 1 starts a new oscillation
phase, the synchronized oscillator is also forced to restart its phase from the beginning.
Between the pulses of Oscillator 1, the synchronized oscillator runs freely.
Synchronized oscillator sounds are especially cool when the frequency of the
synchronized oscillator is modulated by an envelope generator. This way, the number
of phases within a section (phase) of the synchronization cycle always changes, and so
does the spectrum. Typical oscillator sync sounds tend towards the aggressive,
screaming leads that synthesizer manufacturers like to talk about.
Ring (Ring Modulation)
The waveform control of Oscillator 2 also features the Ring setting. In this mode,
Oscillator 2 outputs the signal of a ring modulator. This ring modulator is fed with the
output signal of Oscillator 1 and a square wave of Oscillator 2. The pulse width of this
square wave can be modulated.
A ring modulator has two inputs. At its output you will find the sum and difference
frequencies of the input signals. If you ring-modulate a sine oscillation of 200 Hz with a
sine oscillation of 500 Hz, the output signal of the ring modulator will consist of a
700 Hz (sum) and a 300 Hz (difference) signal. Negative frequencies result in a change
to the phase polarity of output signals. With sawtooth and rectangular input signals,
the output signal is much more complex, as these harmonically-rich waveforms
produce a number of extra side bands.
Note: Ring modulation is a powerful tool for inharmonic, metallic sounds, as the
spectra resulting from its use are inharmonic at almost every frequency ratio. The ring
modulator was the tool of choice for bell-like sounds, and dates back to the early days
of the synthesizer (see the “Ringshifter” section, on page 105).