The origins of the Evolution Variable Character Ladder Filter extend all the way back to the Moog ladder filter, which in turn inspired Dave Rossum to create the E-mu Systems 2100 LPF.
With the Evolution, Rossum Electro-Music have implemented an array of brand new functions that harness all the power of the 2100 while imparting new characteristics alongside new filter types.
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