Operation Manual

6.98 VCS 157
Typical Use
The VCO is used for generating the starting signal of an analog synthesizer. Figure 99 shows a
standard patch using this module.
Figure 99: Typical VCO Use.
6.98 VCS
The VCS module is very similar to the VCO module except that
it only generates sine waves. This module has 2 modulation inputs
and 1 output.
The first input controls the pitch of the output signal. The signal
of this input is multiplied by a value determined by the adjustment
of the mod1 gain knob. The second input signal is used to perform
frequency modulation (FM modulation).
Tuning the Output Pitch
The coarse, fine and range are used to tune the output frequency (or
pitch) to the desired level. The variations in output pitch caused by changes in the modulation
signals are relative to this level. When the two knobs are in their center position (green LEDs on for
the coarse knob), the range knob is in the left position and there is no modulation signal, the playing
frequency has a value of 261.6 Hz, which corresponds to the C3 key on a piano (middle C). The
range knob transposes the pitch by multiplying the frequency appearing in the frequency counter
by the number appearing in the range counter. This enables to generate the different harmonics of
the fundamental frequency appearing in the frequency counter. The reading on the counter gives
the frequency of the output signal, in Hertz, when there is no modulation signal.
Pitch Variation
The amount of variation of the playing frequency obtained with the modulation inputs depends on
the adjustment of the mod1 and FM gain knobs. The total modulation signal is the sum of the two