User's Manual

5.4 The Effects Section 59
wet signal is sent to the output.
5.4.8 Wah Wah
The Multi-Effect module includes 2 different types of Wah effects: wah wah, and auto wah. These
effects are used to enhance a frequency band around a varying center frequency using a bandpass
filter. In the wah wah effect, the center frequency of the bandpass filter varies at a rate fixed by
the user. In the case of 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.
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.
The Mix knob allows one to mix the dry and wet signals. In its leftmost position, there is no
output signal from the chorus and one only ears the dry input signals. In its rightmost position, one
only ears the wet signal from the chorus module. In its center position, there is an equal amount of
dry and wet signal in the output signal from the module. Finally, the Output know is used to adjust
the output level of this module.
5.4.9 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 outside of this band unchanged as
shown in Figure 35. As was the case for the Wah Wah effect, the filter can be modulated.