Operation Manual

6.100 Vkeyboard 159
Cutoff Frequency Variation
The amount of variation of the cutoff frequency obtained with the modulation inputs depends on
the adjustment of the mod1 and mod2 gain knobs. The total modulation signal is the sum of the two
inputs each multiplied by the gain corresponding to its respective mod knob. When the mod knobs
are in the center position (green LEDs on), the gain equals 1 and the pitch variation is 1 Volt/octave.
When the modulation signal is the pitch output from a Keyboard module, this position can be used
to make the cutoff frequency follow an equal temperament scale. The modulation signal of the
second input can be inverted by pressing the inv button.
Typical Use
A Vhighpass2 can be used as a filter to reduce the low frequencies in a signal, as shown in the
following example :
Figure 101: Use of Vhighpass2 to reduce low frequencies.
6.100 Vkeyboard
Similar to the monophonic Keyboard module except that there is an additional
output proportional to the velocity with which a key is depressed. The error knob
introduces some randomness in the pitch signal. Turned to the left, the pitch signal
is correct; as the knob is turned to the right, small fluctuations start to appear in
pitch. The effect of this knob is to simulate pitch variations found in analog synths.
The velocity knob adjusts the velocity curve of the Polyvkey. In the center posi-
tion, the curve is linear. Turned to the left, the velocity increases more quickly;
conversely, turning the knob to the right results in a slower velocity curve.
The default values of the following parameters is set at construction
• pitch wheel range: determines the range of pitch variations that can be obtained with the
pitch wheel. The convention is 1 Volt/octave (maximum value is 2 Volts). A semitone is