Dave Smith Instruments DSM01 Curtis Filter Eurorack Module DSM01 Curtis Filter Module Taking its name from the filter designed by the late Doug Curtis, the DSM01 provides a switchable 2- or 4-pole low-pass filter and a VCA Standard 8HP wide, Eurorack-format device with interconnections made using 3 5 mm jacks Big Sound Comes In Small Packages Dave Smith's first-ever offering for modular synthesizer users is a big one-the DSM01 Curtis Filter, the very heart and soul of the Dave Smith sound