The modular system once developed by Robert "Bob" Moog, including its development process, went through a long production period between 1964 and 1981, when the new electronic instrument was a pioneering avant-garde work that still had to be explained to the public, but eventually found more and more interested parties. Behringer transferred the generously dimensioned decide to the compact Eurorack format and took great care to ensure that sound and function were in no way inferior to the cult object.

The Behringer 904A VC Lowpass Filter is a classic, resonant lowpass filter with a slope of 24 dB/octave and THE famous Moog sound. The Range switch sets the operating range in three steps: 1 (1 Hz - 5 KHz), 2 (4 Hz - 20 KHz) 3 (16 Hz - 80 KHz). Three CV inputs provide control voltages such as keyboard tracking, envelope or LFO. It is recommended to include some attenuators in this module.