A voltage controlled filter on a chip, manufactured by Curtis Electromusic. This was a simpler IC than the more widely used 3320; it could only be configured as a 4-pole, low pass filter. For designers who did not need the multimode capabilities of the 3320, the 3328 offered the advantages of being physically smaller and requiring less external support circuitry. Despite this, it was not widely used. It is known mainly for being used in the Ensoniq Mirage; it was also used in the Bit One and Bit-99/01.