The E440 is an analog discrete low pass filter with three simultaneous filter types (-12dB, -18dB & -24dB).
It also offers overdrive and voltage controlled resonance. The E440´s audio input has a drive control that one one hand is a signal attenuator but on the oter hand it can also amplify signals with the factor 2. You can amplify line level signals and distort the filter´s input. Unity gain is approximately at the "4"-position. A jumper on the modules back activates the bass boost enhancement. The E440 has three filter outputs with slopes of -12dB, -18dB and -24dB/octave, each of them is phase shifted 45° from the prior one.
Mixing the filter outputs will generate different slopes, mixing with inversion will result in different frequency response. For controlling the cutoff frequency there are three CV inputs, the first one working with a characteristic of 1V/octave and tracks over 4 octaves (trimmabla nad temperature compensated), CV input FM1 has an attenuator, FM2 has a polarizer.
The resonance can be voltage controlled as well and the filter can self oscillate at potentiometer position 9. The voltage generated by the resonance pot will be mixed to the external CV.