5.4
The Effects View
65
The spring reverb is turned
on
or
off
by using the
spring
LED in the top right of the section
labelled
Spring
. The
Mix
knob is used to set the amount of wet signal in the mix, turning the knob
clockwise increasing the amount of reverberation in the signal.
Finally, the speaker cabinet is switched
on
or
off
by clicking on the LED in the upper right
corner of the cabinet section of the module. This part of the module simulates the effect of both
the speaker and the cabinet on the frequency response of the amplifier module. The back of the
cabinet can be open or closed using the
Type
selector. Opening the back of the cabinet allows waves
to travel from the back of the cabinet and interfere with those traveling from the front part of the
cabinet resulting in a more colored sound.
5.4.11
Tremolo
The
Tremolo
module is used to modulate the amplitude of the sound. The
Rate
knob is used to
control the speed (frequency) of the modulation while the
Depth
knob controls its amplitude. The
waveform knob is used to change the shape of the waveform used to modulate the sound. In its
leftmost position, the waveform is a triangular and as the knob is turned clockwise it changes to a
smoothed square wave. The
stereo
button is used to switch between stereo and mono mode. When
the button is in its
on
position, the module is in stereo mode and the output signal from bounce
with a 180 degrees phase difference between the left and right channels. In mono mode (button
switched
off
) the signals in the left and right channels are the same.
5.4.12
Reverb
The
Reverb
module 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
since we always listen to instruments in a room and thus with a room effect. This module is located
at the very end of the effects chain in the signal flow.
Impulse Response of a Room
The best way to evaluate the response of a room is to clap hands and to listen to the resulting
sound. Figure 41 shows the amplitude of the impulse response of a room versus time. The first
part of the response is the clap itself, the direct sound, while the remaining of the response is the
effect of the room which can itself be divided in two parts. Following the direct sound, one can
observe a certain amount of echoes which gradually become closer and closer until they can not be