Designing Audio Effect Plug-Ins in C++

CHAPTER 12

Modulated Filter Effects

Modulated filter effects alter one or more filter parameters with other signals called control signals. The filter parameters might include cutoff frequency, Q, bandwidth, filter type, or overall gain. The control signals are usually periodic low-frequency oscillators (LFOs), a signal envelope, an envelope generator (EG) or even another audio signal. In the modulated delay effects, the LFO control signal changed the delay amount of the signal. In modulated filter effects, the filter parameters are the ones that are changing. In this chapter you will design and implement the following effects:

•  Mod filter using an LFO

•  Envelope follower using an audio detector

•  Phaser

The phaser is a specialized effect ...