Operation Manual

38 Parameters
the auto-wah, the variations of the center frequency is controlled by the amplitude envelope of the
incoming signal.
The Freq knob is used to control the central frequency of the filter. Turning this knob clockwise
increases the center frequency. In the case of the Wah Wah effect, the center frequency will oscillate
around the value fixed by the Freq knob while with the Auto Wah effect, the setting of the Freq will
fix the starting point value of the varying center frequency.
The Depth knob controls the excursion of the center frequency of the filter. In the case of
the Wah Wah effect, this excursion is applied around the value fixed by the Freq knob while in
Auto Wah effect the value of the center frequency increases from the value fixed by the Freq knob.
Turning this knob clockwise increases the excursion of the center frequency. Note that the Depth
parameter is also adjustable from the Play view.
Finally, the Rate knob controls the frequency or rate of the modulation of the center frequency
of the filter. In the case of the Wah Wah effect, turning this knob clockwise increases the rate of
the modulation. In the case of the Auto Wah filter, this knob is labeled Speed and controls the time
constant of the envelope follower. Turning this knob clockwise decreases the time constant, or in
other words the reaction time, of the envelope follower.
5.3.9 Notch Filter
The Notch Filter does essentially the
opposite of a band-pass filter. It attenuates
the frequencies in a band located around
the center frequency and leaves those out-
side of this band unchanged as shown in Figure 20. As was the case for the Wah Wah effect, the
filter can be modulated.
The Freq knobs is used to control the central frequency of the filter. Turning this knob clock-
wise increases the center frequency. The Depth knob controls the excursion of the center frequency
of the filter around its center frequency. Turning this knob clockwise increases the excursion of the
center frequency. Finally, the Rate knob controls the frequency or rate of the modulation of the
center frequency of the filter. Turning this knob clockwise increases the rate of the modulation.
Note that the Depth parameter is also adjustable from the Play view.
5.3.10 Reverb
The Reverb effect is used to recreate the effect of reflections of sound on the walls of a room or
hall. These reflections add space to the sound and make it warmer, deeper, as well as more realistic