Variable Character Ladder Filter

Dave Rossum's enhancement of the iconic Moog ladder filter from the original E-mu Systems 2100 LPF module

A Genus control that allows continuous voltage control of the number of filter poles (from 3 to 6 poles), essentially allowing real-time variation of Evolution's effective cutoff slope from 18dB/oct to 36dB/oct. LEDs give continuous indication of the current slope.

A Species control that lets you vary the signal level into the ladder, letting you control the intensity of the filter's characteristic distortion. When in self-oscillation mode, this control modulates the amplitude of Evolution's output.

Voltage controlled resonance with a variable Q Level Compensation control that controls the balance of the resonant peak and the frequencies below the cutoff frequency (which would otherwise be attenuated as the resonance is increased).

An extremely accurate and temperature-stable frequency control exponential generator (accurate over 10 octaves), rivaling the specifications of the best analog VCOs.

Features

• CONTROLS : Initial Frequency, Initial Q, Q Level Compensation, Initial Genus (# of Poles), Initial Species (Ladder Input Level)
• SIGNAL INPUT : 1x 3.5 mm mono socket  – 100 kΩ Input Impedance
• SIGNAL OUTPUT : 1x 3.5 mm mono socket – 1 kΩ Output Impedance
• Frequency CV Inputs : 1x Attenuated - min 50 kΩ Input Impedance, 1x w/Attenuverter - 100 kΩ Input Impedance, 1x 1V/OCT Full Level - 100 kΩ Input Impedance
• Q CV INPUTS : 1x Full Level - 100 kΩ Input Impedance, 1x w/Attenuverter - 100 kΩ Input Impedance
• Genus CV Inputs : 1x Full Level - 100 kΩ Input Impedance, 1x w/Attenuverter - 100 kΩ Input Impedance
• Species CV Inputs : 1x Full Level - 100 kΩ Input Impedance, 1x w/Attenuverter - 100 kΩ Input Impedance

In the Box

• The module itself
• Eurorack Power Cable, screws, nylon washers