Evolution

Rossum Electro-Music 16HP
VCF FILTER OSCILLATOR WAVESHAPER

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Analog variable-character ladder LPF. Re-engineered E-mu 1100 core adds voltage-controlled pole count (3–6), Q-level compensation and Species distortion-drive. DC-coupled · >10-octave range · precise 1V/oct self-oscillation.

Patch Ideas · 8

★ Slope-morphing bass
Genus modulated by slow LFO ±2.5V · Q ~noon (no oscillation) · bass oscillator into INPUT · cutoff at 150Hz · filter slope morphs between 18 and 36 dB/oct cyclically, breathing the low-end character without changing pitch or resonance
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: Evolution, LFO, VCO, Output. Signals: 2 audio, 1 cv.EvolutionLFOVCOOutputFrequency: ~150HzQ: ~noonGenus: noonGenus CV2 attenuverter: ~3 o'clockINPUTaudioGENUS CV2cvOUTPUTaudioOutcvOutaudioInaudioaudiocv
Pole-count arpeggio
no input · Q maxed (continuous oscillation) · Frequency set to A4 · square LFO into GENUS CV1 · Evolution jumps between four oscillation pitches (+10, 0, -6, -10.5 semitones of cutoff) as Genus steps across pole counts — self-generating arpeggio
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 2 connections. Modules: Evolution, LFO, Output. Signals: 1 audio, 1 cv.EvolutionLFOOutputQ: maximumFrequency: A4Genus: sweep rangeGENUS CV1cvOUTPUTaudioOutcvInaudioaudiocv
Precision sine VCO
no input · Q just at oscillation · Genus at 4 poles · sequencer 1V/oct into 1V/OCT · Evolution becomes a clean, 10-octave-tracking sine VCO — use as a fifth voice or sub when your VCOs are maxed out
▸ Show diagram
Patch diagramPatch diagram with 3 modules and 2 connections. Modules: Evolution, Sequencer, VCA. Signals: 1 audio, 1 pitch.EvolutionSequencerVCAQ: at oscillation thresholdGenus: 4 polesFrequency: base pitch1V/OCT1v/octOUTPUTaudioPitch1v/octInaudioaudiopitch
★ Through-zero filter FM
Genus 5 poles · Q high · audio-rate VCO into FREQ CV2 with attenuverter swept through noon · bipolar FM crosses zero · harsh metallic inharmonic tones built from ladder-filter self-oscillation
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: Evolution, Modulator VCO, Audio VCO, Output. Signals: 2 audio, 1 cv.EvolutionModulator VCOAudio VCOOutputGenus: 5 polesQ: high (near oscillation)INPUTaudioFREQ CV2cvOUTPUTaudioOutcvOutaudioInaudioaudiocv
★ Fat resonant bass
Q ~3 o'clock · Q LEVEL COMPENSATION fully CW · cutoff 200Hz tracked with keyboard · Species at ~1 o'clock for warmth · the low body stays full under high resonance instead of thinning — aggressive acid bass without the classic ladder thin-out
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: Evolution, Bass VCO, Keyboard, VCA. Signals: 2 audio, 1 pitch.EvolutionBass VCOKeyboardVCAQ: ~3 o'clockQ Level Compensation: full CWSpecies: ~1 o'clockFrequency: ~200HzINPUTaudio1V/OCT1v/octOUTPUTaudioOutaudioPitch1v/octInaudioaudiopitch
Species ring-mod
self-oscillating · audio-rate sine into SPECIES CV1 · Species now amplitude-modulates the oscillator output (inverse to Q feedback) · combine with a carrier signal into INPUT for ring-mod-like sum-and-difference tones
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: Evolution, Modulator, Carrier, Output. Signals: 2 audio, 1 cv.EvolutionModulatorCarrierOutputQ: maximumSpecies: noonGenus: 4 polesINPUTaudioSPECIES CV1cvOUTPUTaudioOutcvOutaudioInaudioaudiocv
Generative slew
CV source into INPUT (DC-coupled) · Q low · Genus 3 poles · Frequency ~100Hz · Evolution acts as a gentle slew limiter on the CV · modulate Genus from another LFO to dynamically shift smoothing character from soft (3 poles) to sharp (6 poles)
▸ Show diagram
Patch diagramPatch diagram with 4 modules and 3 connections. Modules: Evolution, S&H, Shape LFO, VCO. Signals: 2 cv, 1 pitch.EvolutionS&HShape LFOVCOGenus: 3 poles (start)Q: lowFrequency: ~100HzINPUTcvGENUS CV1cvOUTPUT1v/octOutcvOutcvV/Oct1v/oct121. CV processed2. dynamic glidecvpitch
Dual CV envelope LPF
keyboard 1V/oct into 1V/OCT · envelope into FREQ CV2 with attenuverter noon→CW for positive sweep · LFO into FREQ CV3 with attenuator low for vibrato · three-source CV sum via the three independent frequency inputs with no external mixer
▸ Show diagram
Patch diagramPatch diagram with 6 modules and 5 connections. Modules: Evolution, Envelope, LFO, Keyboard, Source, VCA. Signals: 2 audio, 2 cv, 1 pitch.EvolutionEnvelopeLFOKeyboardSourceVCAQ: ~2 o'clockFrequency: ~500HzINPUTaudio1V/OCT1v/octFREQ CV2cvFREQ CV3cvOUTPUTaudioOutcvOutcvPitch1v/octOutaudioInaudioaudiocvpitch

Behaviors

Voltage-controlled pole count GENUS knob or GENUS CV

Steers current through individual ladder stages in an analog continuous manner between 3 and 6 poles. LEDs show current integer pole count; two adjacent LEDs indicate the control is mid-transition. Modulating at LFO rates reshapes the filter's slope dynamically; at audio rates produces entirely new timbres not available from classic ladder filters.

Genus shifts resonant pitch GENUS change with Q near or at self-oscillation

The 180° phase-shift frequency differs per pole count: at 3 poles resonance sits 10 semitones above cutoff, 4 poles equal to cutoff, 5 poles 6 semitones below, 6 poles 10.5 semitones below. Modulating Genus during self-oscillation sweeps the pitch between these anchor points — arpeggiator-like patterns from a single CV.

Oscillation continuity vs break Q at maximum vs just at onset · moving Genus

With Q maxed, oscillation is continuous through all Genus transitions. With Q set just at self-oscillation threshold, moving Genus causes Evolution to stop oscillating between pole settings (the Q needed for oscillation differs per pole). Pick threshold-Q for gated arpeggios, max-Q for smooth pitch sweeps.

Q Level Compensation Q LEVEL COMPENSATION knob

Classic ladders attenuate the passband as Q rises, giving the familiar thin resonant wah. CCW preserves that behavior. CW progressively mixes the pre-ladder signal back in, keeping body and low-end intact under high resonance — useful for resonant pads and fat bass that would otherwise sound gutted.

Species drive vs oscillation SPECIES knob · with Q high

Because Q feedback lives inside the drive VCAs, Species does not affect resonance height but does inversely control self-oscillation amplitude. When self-oscillating, higher Species = quieter oscillator; Species CV thus amplitude-modulates the oscillator output. Combining audio-rate Species CV with an input signal produces ring-mod-like cross-modulation.

Sine-wave VCO mode Q ~4V+ · no input

Self-oscillation produces a clean high-fidelity sine. 1V/OCT tracks accurately over 10+ octaves (better than many Eurorack VCOs). Purest sine with Genus at 4 poles and Q just barely into oscillation. Evolution doubles as a sine-only VCO with filter FM/AM capabilities via Species.

DC-coupled CV processing CV patched to INPUT

DC-coupled throughout. Patching an LFO or envelope into INPUT lets Evolution smooth, slew or amplify CVs. With Genus at 3 poles the response is a slow RC-style lag; at 6 poles a steeper response. Self-oscillating with CV in causes quadrature-like behavior useful for complex modulation shapes.

Three frequency CVs sum 1V/OCT + FREQ CV2 + FREQ CV3 all patched

1V/OCT is full-level fixed. FREQ CV2 has an attenuverter (sign-flippable). FREQ CV3 has a plain attenuator (positive only). All three sum with the FREQUENCY knob. Gives simultaneous key-tracking, bidirectional envelope and scaled LFO modulation without external mixers.

Controls

Global FREQUENCY Initial cutoff frequency. Summed with all frequency CVs.
~22Hz – 22kHz (knob alone) · 0.02Hz – 40kHz with CVs
Frequency FREQ CV3 attenuator Conventional attenuator for FREQ CV3 input.
CCW: no CV · CW: full amplitude at 1V/oct
Frequency FREQ CV2 attenuverter Attenuverter for FREQ CV2 input.
CCW: full inverted · noon: 0 · CW: full direct · both ends at 1V/oct
Resonance Q Initial resonance height. ~4V enters self-oscillation.
0 – 7V effective range · approximately linear VCA-controlled Q
Resonance Q LEVEL COMPENSATION Restores passband level lost as Q rises. CCW: classic ladder thinning. CW: full pre-attenuation body preserved.
Continuous mix between thin/resonant-only and full-body signal
Resonance Q CV2 attenuverter Attenuverter for Q CV2 input.
CCW: invert · noon: 0 · CW: unity
Pole count GENUS Initial number of active poles in the ladder. Continuous analog current-steering, not switched.
3 poles (18dB/oct) – 6 poles (36dB/oct) · 5V swing covers full range
Pole count GENUS CV2 attenuverter Attenuverter for GENUS CV2 input.
CCW: invert · noon: 0 · CW: unity
Drive SPECIES Signal level into ladder. Controls distortion of frequencies near/above cutoff.
0 – 10V range · up to noon: subtle · past noon: audible grit
Drive SPECIES CV2 attenuverter Attenuverter for SPECIES CV2 input.
CCW: invert · noon: 0 · CW: unity

I/O

IN · 10

  • INPUT up to 20Vpp CV
    DC-coupled audio/CV input
  • 1V/OCT 1V/oct · 100kΩ CV
    Calibrated full-level pitch CV for cutoff · 10+ octave tracking
  • FREQ CV2 1V/oct at extremes · 100kΩ CV
    Attenuverted frequency CV (sign-flipping)
  • FREQ CV3 1V/oct at max · 50kΩ min CV
    Attenuated frequency CV (positive only)
  • Q CV1 summed with Q knob · 100kΩ CV
    Full-level Q control voltage
  • Q CV2 100kΩ CV
    Attenuverted Q CV
  • GENUS CV1 5V swing covers 3→6 poles · 100kΩ CV
    Full-level pole-count CV
  • GENUS CV2 100kΩ CV
    Attenuverted pole-count CV
  • SPECIES CV1 100kΩ CV
    Full-level drive CV
  • SPECIES CV2 100kΩ CV
    Attenuverted drive CV

OUT · 1

  • OUTPUT up to 20Vpp without clipping AUDIO
    Filtered audio · DC-coupled · 1kΩ