Operation Manual

6.96 VCA (Voltage Controlled Amplifier) 154
Center Frequency Variation
The amount of variation of the center 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 they 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 note output from a Keyboard module, this position can be used
to make the center frequency follow an equal temperament scale. The modulation signal of the
second input can be inverted by pressing the inv button. This can be useful when generating bass
sounds, for example, where one wants to close the filter with an upward going envelope such as
during the attack of a note.
Typical Use
A Vbandpass2 and an ADSR module can be used to obtain an auto wah wah effect. In this
example, the center frequency of the filter is modulated with the output from the ADSR module.
Figure 95: Auto wah wah effect obtained with an ADSR and Vbandpass2 module.
Note: See also the Bandpass2 module.
6.96 VCA (Voltage Controlled Amplifier)
The VCA module has two input signals, a signal to be amplified, and a gain. The output is the
product of the two inputs. This module has no front panel control.