Flanger Speed and Excursion

As mentioned above, the delay-line length $M(n)$ in a digital flanger is typically modulated by a low-frequency oscillator (LFO). The oscillator waveform is usually triangular, sinusoidal, or exponential (triangular on a log-frequency scale). In the sinusoidal case, we have the following delay variation:

$$M(n) = M_0 \cdot \left[1 + A\sin(2\pi f n T)\right]$$

where $f$ is the ``speed'' (or ``rate'') of the flanger in cycles per second, $A$ is the ``excursion'' or ``sweep'' (maximum delay swing) which is often not brought out as a user-controllable parameter, and $M_0$ is the average delay length controlling the average notch density (also not normally brought out as a user-controllable parameter).