The Moog 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 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 the knobs. Panel switches select filter mode and envelope follower speed. Made in the USA.