Operation Manual

6.58 Phaser 116
Figure 62: Panpot modulated by LFO.
The default value of the following parameters is set at construction
• Angle: default source position. A value of 0 positions the source on the left, 0.5 in the middle
and 1 on the right.
• Range: determines the maximum possible amount of source excursion from its original po-
sition, varies between 0 and 0.5 (90 degrees).
6.58 Phaser
The Phaser module implements the effect known as “phasing” which
colors a signal by removing frequency bands from its spectrum. The effect
is obtained by changing the phase of the frequency components of a signal
using an all-pass filter and adding this new signal to the original one. This
module has two inputs and one output. The first input is the audio signal
to be phased and the second input is a modulation signal that varies the
phase variations introduced in the spectrum of the first input signal. The
output is the phased signal.
The algorithm implemented in this module is shown in Figure 63. The
input signal is sent into a variable fourth order all-pass filter. This “wet” signal is then mixed down
with the original “dry” signal. A feedback line allows the resulting signal to be re-injected into the
filter. The effect of the Phaser module is to introduce rejection in the spectrum of the input signal
depending on the tuning of the filter.
The all-pass filter modifies a signal by delaying its frequency components with a delay which
increases with the frequency. This phase variations will introduce a certain amount of cancellation
when this “wet” signal is mixed down with the original “dry” signal as shown in Figure 64. The
rejection is maximum when the phase delay is equal to 180 degrees and a given component is out of
phase with that of the original signal. The amount of effect is determined by the ratio of “wet” and
“dry” signal mixed together as shown in Figure 64. As the amount of “wet” signal sent to the output
is reduced, the amount of rejection increases. The shape of the frequency of the Phaser module is
also influenced by the amount of “wet” signal re-injected into the feedback loop. Increasing the
feedback enhances frequency components least affected by the all-pass filter. As the feedback is