The award-winning MF-101 Lowpass Filter is a direct descendant of the original Moog modular synthesizers. It contains two complete modular functions: a voltage-controlled lowpass filter and an envelope follower. It can be used with any instrument-level to line level-signal.The moogerfooger filter’s control parameters are signal mix, cutoff frequency, resonance amount, and envelope amount. All of the Lowpass Filter’s parameters can be controlled with expression pedals or external control voltages as well as by great feeling knobs which beg to be tweaked. Panel switches select filter mode and envelope follower speed. 1/4 jacks are provided for audio input and output, pedal/control inputs and envelope follower output. A heavy-duty, yet smooth-acting bypass switch allows tabletop or foot operation. A lowpass filter removes high frequencies from a tone. It makes the tone sound more mellow or muted. The lower the Cutoff, the more muted the tone sounds. Imagine a window shade. As it is pulled down, it cuts out the higher light, then the light from the middle of the window, then finally all the light. The MF-101 Lowpass Filter does the same sort of thing to the sound spectrum with it’s Cutoff Control.As you turn up the Resonance control, the overtones near the cutoff frequency are boosted. Resonance gives the moogerfooger filter the same classic Moog filter sound as the Minimoog; and Moog modular synthesizers. The envelope follower tracks the loudness contour (envelope) of a sound, and produces a voltage that follows the dynamics of your playing. Every time you play a note, the envelope voltage goes up and then down. The harder you play, the higher the envelope voltage goes. The envelope follower opens and closes the lowpass filter. Think of the envelope voltage as an invisible hand that turns the CUTOFF knob up and down every time you play a note. Since the envelope follows the dynamics of your instrument’s signal, you actually play the filter as you play your instrument.