Phasers:

IMPORTANT: In order to achieve a feedback phaser effect, this component must be connected in parallel with the original signal, thereby creating a time-varying notch filter. (On its own, it simply acts as a time-varying all-pass filter (with feedback) and will not produce a phaser effect.) The characteristics of the resulting notch filter depend on the settings of the time-varying all-pass filter and on the feedback gain. All quantities are adjustable via the Parameter Window, as summarised in the following table. Since the intended use is in parallel with the original signal to create a notch, the all-pass parameters are described in terms of the resulting notch. Stereo signals have separate adjustments for left and right channels.

Parameter	Purpose
"Lower" slider	Sets the lower limit for the center-frequency of the sweeping notch (within the allowable range extending from 0 up to the Nyquist frequency (i.e. half the sample rate)).
"Upper" slider	Sets the upper limit for the center-frequency of the sweeping notch (within the allowable range extending from the lower limit up to the Nyquist frequency).
"Rate" slider	Sets the rate (in Hz) at which the notch center-frequency sweeps through its profile from the lower limit to the upper limit. The sweep follows an exponential rise from the lower limit to the upper limit, followed by an exponential decay from the upper limit to the lower limit.
"Skew" slider	Adjusts the time-asymmetry of the shape of the exponential frequency sweep. A value of 0.5 corresponds to a symmetric profile (i.e. the rise profile is a mirror image of the decay profile).
"Width" slider	Adjusts the bandwidth of the notch as a fraction of the instantaneous center-frequency. As the center-frequency sweeps through its exponential profile, the bandwidth thereby adjusts accordingly.
"Depth" slider	Adjusts the depth of the notch filter. Maximum depth (lower limit of slider) implies a deep notch; minimum depth (upper limit of slider) implies a shallow notch. The depth is fixed in time.
"Feedback" slider	Adjusts the internal feedback gain. (CAUTION: values approaching unity can lead to undesirable instabilities.)
"Feedback polarity switch" checkbox	Toggles the polarity of the internal feedback gain (i.e. switches between negative and positive feedback).
"Output" slider	Adjusts the amplitude of the output signal.

NOTE: A multi-stage (i.e. multi-notch) phaser can be obtained by connecting multiple copies of this component in series, then connecting this cascade in parallel with the original signal. (This works because a cascaded series of all-pass filters retains the all-pass characteristics, which results in a set of notches when connected in parallel with the original signal.)

Algorithm