Operation Manual

4.9 The Multi-Effect Module 33
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.
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 if the Sync function is off. In the case of the Auto Wah filter, this knob 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.
4.9.6 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 11. As was the case for the Wah Wah effect, the filter is based on a filter having a
12 dB/oct slope and can be modulated.
Amplitude (dB)
Frequency (Hz)
0dB
−3dB
Center
Frequency
Band Width (Q=1)
Figure 11: Frequency response of a notch filter.
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