Operation Manual

6.99 Vhighpass2 158
inputs each multiplied by the gain corresponding to their respective knob. When the mod1 knob is
in the center position (green LEDs on), the gain equals 1 and the pitch variation is 1 Volt/octave.
This position is used to play an equal temperament scale when connecting the output of a Keyboard
module to this modulation input. The FM modulation input is used to apply frequency modulation
to the signal generated by the VCS module. The amount of frequency modulation applied by the
modulation signal is controlled with the FM knob.
Typical Use
The FM synthesis technique can be reproduced by using VCS modules connected in cascade as in
the following example.
Figure 100: FM synthesis with VCS modules.
6.99 Vhighpass2
The Vhighpass2 module is a voltage-controlled second-order high-pass fil-
ter (-12dB/octave). This module has three inputs and one output. The first input
is the signal to be filtered, while the second and third inputs are modulation sig-
nals which are used to vary the cutoff frequency of the filter. The amplitude of
the two modulation signals is adjusted with the two gain knobs mod1 and mod2
respectively. The output is the filtered signal.
Tuning the Cutoff Frequency
The cutoff frq knob tunes the cutoff frequency to the desired level. The varia-
tions in the cutoff frequency, caused by changes in the modulation inputs, are
relative to this level. The resonance knob is used to emphasize the frequencies near the cutoff
frequency as shown in the following figure: