User`s manual

Page 20
Voyager OS User’s Manual - The Components
Page 21
Voyager OS User’s Manual - The Components
Filter Section Controls:
Cutoff:
The
CUTOFF
knob is the main  lter control. This sets the cutoff frequency of both  lters in Dual Lowpass
and Highpass/Lowpass mode.
In Dual Lowpass mode, the frequencies to the right of the indicator on the knob are the frequencies that
are  ltered out. The frequencies to the left of the indicator are the frequencies that are allowed to pass
through the  lter. This is why as you turn the control clockwise the cutoff frequency becomes higher and
the sound becomes brighter. Of course, to hear the effect of a lowpass  lter it helps to have a signal rich
in harmonics which provides high frequencies to  lter. A good example of a sound rich in harmonics is a
sawtooth waveform.
In Highpass/Lowpass mode, the combination of highpass and lowpass  lters forms a bandpass  lter. In this
mode, the
CUTOFF
control changes the center frequency of the passband.
Spacing:
The
SPACING
control is used to determine the difference between the cutoff frequencies of the two  lters
in both Dual Lowpass mode and Highpass/Lowpass mode. The numbers on the legend around the control
knob refer to octaves. When the
SPACING
control knob is centered, the cutoff frequencies of the two
 lters are identical and the  lter sounds like a classic Moog Filter. Setting the
SPACING
control to +1 in
Dual Lowpass mode means that the right  lter has a cutoff frequency equal to where the
CUTOFF
control
knob is set, and the left frequency has a cutoff frequency that is one octave higher than the right  lter. This
means when the
CUTOFF
control is swept, two resonant peaks are heard, giving the  lter a unique quality.
In Highpass/Lowpass mode, the
SPACING
control sets the difference between the cutoff frequencies by
shifting the Highpass  lter cutoff frequency up or down. When the
SPACING
control is fully clockwise, the
cutoff frequencies of the two  lters are the same, making for a very narrow bandpass  lter.
Resonance:
The
RESONANCE
control causes feedback in the  lter circuit that adds harmonic emphasis at the cutoff
frequency. This control affects the Lowpass  lter(s) in either  lter mode, but not the Highpass  lter. When
the
RESONANCE
control is all the way down, the lowpass  lters act as a tone control, rolling off the high
end (treble) as the
CUTOFF
control is turned down. As the resonance increases, the  lter begins to form
a peak at the cutoff frequency. These peaks reinforce the harmonics of the signal being  ltered, creating an
effect that can be described as vocal, nasal, or (at high resonances) zappy. As the
RESONANCE
control is
turned up the peak increases in strength until the control is set to about 8 or higher, where it begins to self-
oscillate, creating sine waves with the same frequency as the cutoff frequency.
Keyboard Control Amount:
The
KEYBOARD CONTROL AMOUNT
knob allows the  lter cutoff to follow the key played on the
Voyager keyboard. A higher key will cause a higher cutoff frequency. This allows a sound to retain its
brightness as it is played higher on the keyboard.
Mode:
The  lter
MODE
switch selects either the Dual Lowpass con guration (DUAL LP) or the Highpass/Lowpass
con guration (HP/LP).