Quad AAF (BLACK)

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 separate 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