Phaser Built From Scratch_2

What it does

Complete phaser built from scratch

The heart of this phaser algorithm is the Controllable 2-pole allpass filter whose frequency response has a flat magnitude spectrum but a nonlinear phase response. When the allpass filter is connected in parallel with the original dry signal (via the Linear Mixer), the net effect is a notch filter. The key to achieving the classical "phaser" effect is to vary the allpass filter coefficients in time, such that the notch filter varies in time. The Controllable 2-pole allpass block is designed for this purpose. The first Control Input is the instantaneous centre frequency of the notch (when the parallel dry branch is connected), and the second Control Input specifies the instantaneous bandwidth of the notch. In this example, the centre frequency is driven by the Exponential Sweep Control Generator which generates a control signal (in Hz) which sweeps exponentially in time across a desired frequency range. The bandwidth of the notch is made to be equal to a constant fraction of the centre frequency (achieved using the Constant Control Generator and the Multiply Controls blocks).

The limiter ensures that the output doesn't cause digital clipping arising from constructive interference of the dry signal with the notched signal.

You can experiment with different types of sweep signal for both the centre frequency and the notch bandwitdh. (The exponential sweep demonstrated here just happens to be a common phaser implementation).

Try changing all parameter settings of all components to achieve a wide range of interesting phasing effects.

Effects used

Linear Mixer (2-in)Multiply Controls Limiter Controllable 2-Pole Allpass Exp Sweep (F)Constant (A)

8 blocks 9 connections

In WaveWarp, 1998

How the original documented it

Complete phaser built from scratch The heart of this phaser algorithm is the Controllable 2-pole allpass filter whose frequency response has a flat magnitude spectrum but a nonlinear phase response. When the allpass filter is connected in parallel with the original dry signal (via the Linear Mixer), the net effect is a notch filter. The key to achieving the classical "phaser" effect is to vary the allpass filter coefficients in time, such that the notch filter varies in time. The Controllable 2-pole allpass block is designed for this purpose. The first Control Input is the instantaneous centre frequency of the notch (when the parallel dry branch is connected), and the second Control Input specifies the instantaneous bandwidth of the notch. In this example, the centre frequency is driven by the Exponential Sweep Control Generator which generates a control signal (in Hz) which sweeps exponentially in time across a desired frequency range. The bandwidth of the notch is made to be equal to a constant fraction of the centre frequency (achieved using the Constant Control Generator and the Multiply Controls blocks). The limiter ensures that the output doesn't cause digital clipping arising from constructive interference of the dry signal with the notched signal. You can experiment with different types of sweep signal for both the centre frequency and the notch bandwitdh. (The exponential sweep demonstrated here just happens to be a common phaser implementation). Try changing all parameter settings of all components to achieve a wide range of interesting phasing effects.

Components used (1998)

Output Single-Mono WAVE DriverLinear MixerInput WAV fileMultiply ControlsAudio LimiterControllable 2-pole allpassExponential Sweep Control Generator (F)Constant Control Generator (A)