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The included VST instruments
Ring modulation
Ring modulators multiply two audio signals. The ring-mod-
ulated output contains added frequencies generated by
the sum of, and the difference between, the frequencies of
the two signals. In Prologue, Osc 1 is multiplied with Osc
2 to produce sum and difference frequencies. Ring modu
-
lation is often used to create bell-like sounds.
• To hear the ring modulation, turn down the output level
for Osc 1 and 2, and turn up the “R.Mod” level all the way.
• If Osc 1 and 2 are tuned to the same frequency, and no
modulation is applied to the Osc 2 pitch, nothing much
happens.
However, if you change the pitch of Osc 2, drastic changes in timbre can
be heard. If the oscillators are tuned to a harmonic interval such as a fifth
or octave, the ring modulated output sounds harmonic, other intervals
produce inharmonious, complex timbres.
• Deactivate Oscillator Sync when using ring modulation.
Noise generator
A noise generator generates noise (all frequencies at
equal levels). Applications include simulating drum
sounds and breath sounds for wind instruments.
• To hear only the sound of the noise generator, turn
down the output level for the oscillators, and turn up the
Noise parameter.
• The noise generator level is routed to Envelope 1 by de-
fault.
See “Envelope page” on page 36 for a description of the Envelope gen-
erators.
Filter section
The circle in the middle contains the filter parameters. The
central control sets the filter cutoff parameter and the
outer ring the filter type:
Parameter Description
Filter type Sets the filter type to either low pass, high pass, band
pass or notch. The filter types are described in the table
below.
Cutoff This knob controls the filter frequency or “cutoff”. If a low
pass filter is used, it could be said to control the opening
and closing of the filter, producing the classic “sweeping”
synthesizer sound. How this parameter operates is gov
-
erned by the filter type mode (see the table below).
Emphasis This is the resonance control for the filter. For low pass and
high pass filters, raising the Emphasis value emphasizes
the frequencies around the set cutoff frequency. This pro
-
duces a generally thinner sound, but with a sharper, more
pronounced cutoff sweep. The higher the filter Emphasis
value, the more resonant the sound becomes until it starts
to ring (self-oscillate), generating a distinct pitch. For Band
pass or Notch filters, the Emphasis setting adjusts the
width of the band. When you raise the value, the band
where frequencies are let through (Band pass), or cut
(Notch) becomes narrower.
Drive This can be used to adjust the filter input level. Levels
above 0
dB gradually introduce a soft distortion of the in-
put signal, and a decrease of the filter resonance.
Shift Internally, each filter consists of two or more “subfilters”
connected in series. This parameter shifts the cutoff fre
-
quency of the subfilters. The result depends on the se-
lected filter type: For Low pass and High pass filter types
it changes the filter slope. For Band pass and Notch filter
types it changes the bandwidth. The Shift parameter has
no effect if either the 12
dB LP or 12 dB HP filter type is
selected.
Tracking If this parameter is set to values over the 12 o’clock posi-
tion, the filter cutoff frequency increases the further up on
the keyboard you play. Negative values invert this rela
-
tionship.
If the Tracking parameter is set fully clockwise, the cutoff
frequency tracks the keyboard by a semitone per key.