APPLIED ACOUSTICS SYSTEMS STRINGSTUDIO Manuel d'utilisateur télécharger pdf (Page 45)

4.3 The FX View 45

used to ﬁx the ratio of wet signal re-injected into the delay. Finally, the Mix knob determines the

amount of dry and wet signal in the output signal from the module. When this knob is adjusted in

its leftmost position, only dry signal is sent to the output, in its center position, there is an equal

amount of dry and wet signal in the output signal while in its rightmost position, only wet signal is

sent to the output. Note that the Depth parameter is also adjustable from the Play view.

4.3.7 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.

The algorithm implemented in this module is shown in Figure 28. The input signal is sent into a

variable 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.

Figure 28: Phaser algorithm.

The all-pass ﬁlter modiﬁes a signal by delaying its frequency components with a delay which

increases with the frequency. This phase variations introduce a certain amount of cancellation when

this wet signal is mixed down with the original dry signal as shown in Figure 29. The rejection is

maximum when the phase delay is equal to 180 degrees and a given component is out of phase with

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APPLIED ACOUSTICS SYSTEMS STRINGSTUDIO Manuel d'utilisateur Page 45