This is a two pole multimode filter capable of high pass, low pass, band pass and notch output modes. All four outputs are available simultaneously. This very popular Oakley design is based around the classic two pole state variable filter as used in a variety of vintage synths including Oberheim SEM and OB-Sx. The Oakley SVF uses high quality linearised OTA ICs to create a clean, low noise filter. The filter will oscillate over most of the audio band and is temperature compensated.