EP4 Manual

34 Parameters
Figure 14: Flanger algorithm.
The effect of the Flanger module is to introduce rejection in the spectrum of the input signal at
frequencies located at odd harmonic intervals of a fundamental frequency as shown in Figure 15.
The location of the fundamental frequency f 0 and the spacing between the valleys and peaks of
the frequency response is determined by the length of the delay line (f 0 = 1/(2delay)), the longer
the delay, the lower is f 0 and the smaller the spacing between the harmonics while decreasing the
delay increases f 0 and hence the distance between the harmonics.
0 dB
Amp
Frequency
Long Delay Time
0 dB
Amp
Frequency
Short Delay Time
Figure 15: Frequency response of a Flanger module. Effect of the length of the delay line.
The amount of effect is determined by the ratio of wet and dry signal mixed together as shown
in Figure 16. As the amount of wet signal sent to the output is increased, the amount of rejection
increases. Finally, the shape of the frequency response of the Flanger module is also influenced
by the amount of wet signal re-injected into the feedback loop as shown in Figure 17. Increasing
the feedback enhances frequency components least affected by the delay line and located at even
harmonic intervals of the fundamental frequency. As the feedback is increased, these peaks become
sharper resulting in an apparent change in the pitch of the signal.