Category Archives: Filters

The digital state variable filter

The digital state variable filter was described in Hal Chamberlin’s Musical Applications of Microprocessors. Derived by straight-forward replacement of components from the analog state variable fiter with digital counterparts, the digital state variable is a popular synthesizer filter, as was its … Continue reading

Posted in Digital Audio, Filters, IIR Filters | 21 Comments

Biquads

One of the most-used filter forms is the biquad. A biquad is a second order (two poles and two zeros) IIR filter. It is high enough order to be useful on its own, and—because of coefficient sensitivities in higher order … Continue reading

Posted in Biquads, Digital Audio, Filters, IIR Filters | 30 Comments

Pole-Zero placement

Use the new, improved pole-zero calculator—but be sure to read the “Experiments with standard biquads” section below for tips on placing poles and zeros for standard filters. Here’s a Java applet that illustrates pole-zero placement. It lets you design a … Continue reading

Posted in Biquads, Digital Audio, Filters, IIR Filters, Widgets | 8 Comments