SALLEN KEYSALLEN KEY is our tribute of the legendary MS 20 filter. We've tried our best to honor this unique and iconic filter. Its composed of a 2 Poles Low Pass and a 1 Pole High Pass. Unlike the original we add a crossader allowing you to blend the Low Pass and High Pass filters to create complex filtering. What make this filter special it is non linear feedback path. This design avoid the filter to clipping when self oscillating, but also give it is unique