Plug-in Reference

50
The included VST Instruments
• The Ratio parameter determines the amount of frequency
modulation.
Portamento
This parameter makes the pitch glide between the notes
you play. The parameter setting determines the time it
takes for the pitch to glide from one note to the next. Turn
the knob clockwise for longer glide time.
The “Mode” switch allows you to apply glide only when
you play a legato note (when switch is set to Legato). Le-
gato is when you play a note without releasing the previ-
ously played note. Note that Legato mode only works with
monophonic Parts.
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, you should 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
will happen.
If you change the pitch of Osc 2, however, 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 will sound harmonic, other intervals
will produce inharmonious, complex timbres.
• Oscillator Sync should be deactivated 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, you
should turn down the output level for the oscillators, and
turn up the Noise parameter.
• The Noise generator level is routed to Envelope 1 by
default.
See “Envelope page” on page 53 for a description of the Envelope gen-
erators.
Filter section
The circle in the middle contains the filter parameters. The
central dial sets the filter cut off parameter and the outer
ring the filter type:
Parameter Description
Filter type Sets the filter type to either lowpass, highpass, bandpass
or notch. The filter types are described on “About the fil-
ter types” on page 51.
Cut off This dial controls the filter frequency or “cut off”. If a low-
pass filter is used, it could be said to control the opening
and closing of the filter, producing the classic “sweep-
ing” synthesizer sound. How this parameter operates is
governed by the filter type mode (see “About the filter
types” on page 51).
Emphasis This is the resonance control for the filter. For lowpass
and highpass filters, raising the Emphasis value will em-
phasize the frequencies around the set cutoff frequency.
This produces a generally thinner sound, but with a
sharper, more pronounced cutoff sweep. The higher the
filter Emphasis value, the more resonant the sound be-
comes until it starts to ring (self-oscillate), generating a
distinct pitch. For Bandpass or Notch filters, the Empha-
sis setting adjusts the width of the band. When you raise
the value, the band where frequencies are let through
(Bandpass), or cut (Notch) will become narrower.
Drive This can be used to adjust the filter input level. Levels
above 0dB will gradually introduce a soft distortion of the
input 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 Lowpass and Highpass filter types it
changes the filter slope. For Bandpass and Notch filter
types it changes the bandwidth. The Shift parameter has
no effect if either the 12dB LP or 12dB HP filter type is
selected.
Tracking If this parameter is set to values over the 12 o’clock posi-
tion, the filter cutoff frequency will increase the further up
on the keyboard you play. Negative values invert this rela-
tionship.
If the Track parameter is set fully clockwise, the cutoff fre-
quency will track the keyboard by a semitone per key.