The Stoel Music Systems Norton Filter is a 24db/octave voltage-controlled lowpass filter based on the later versions of the ARP 2600 filter. It uses a peculiar type of amplifier device known as a Norton amplifier, originating in the mid-1970s and finding applications in electronic music and analog video processing. The filter core consists of four Norton amplifiers and four precision-matched, German-made Wima film/foil capacitors to provide excellent stability and a sharp filter response. The iconic resonant sound of this filter is one of the main reasons it is still sought after today. Our version of this filter adds voltage-controlled resonance to expand and automate the creative possibilities. This module has an audio input and output jack, a 1V/octave frequency CV input, another variable CV input with a knob, and a variable resonance CV input with a knob. There is also a knob for input level control, filter cutoff frequency, and resonance amount.