Quad AAF

Quad Anti Aliasing Filter

The WMD Quad Anti Aliasing Filter (QAAF) was conceptualized as the first expansion for the Phase Displacement Oscillator. It is designed to eliminate aliasing and stair-step distortion from the Digital to Analog converters. We opted to make this a seperate module because it is useful by itself as well as coupled with the PDO.

There are four independent filters inside the QAAF. Each -24dB/octave Butterworth filter runs at exactly the same frequency. The Butterworth filter has a small amount of resonance and a great sound. Each input jack is normaled from the expansion header that connects to the PDO, but any signal can be filtered by plugging in.

The frequency control circuitry uses a vactrol to control the clocking speed of each filter, slowing down the response to transient signals. This brings life and character to the sound.

https://www.wmdevices.com/collections/eurorack-modules/products/quad-anti-aliasing-filter-qaaf