befaco-even-vco

Befaco Even VCO

Precision analog VCO with signature even harmonics output

8 HP Eurorack module

The Even VCO is a precision analog voltage-controlled oscillator by Befaco offering exceptional tuning stability and 1 cent tracking accuracy over 10 octaves. It features five simultaneous waveform outputs including the signature Even output which produces only even harmonics for a distinctive hollow, clarinet-like timbre. A redesigned temperature compensation circuit ensures stability against voltage and temperature fluctuations, and a linear through-zero FM input enables metallic bell-like timbres.

Features

  • 10-position octave rotary switch (32', 16', 8', 4', 2', 1', 1/2', 1/4', 1/8', 1/16')
  • 1 cent precision pitch tracking over full 10-octave range
  • Five simultaneous waveform outputs: Sawtooth, Even, Sine, Triangle, Pulse
  • Signature Even output containing only even harmonics (2nd, 4th, 6th, 8th...)
  • Two V/Oct inputs summed internally
  • Linear through-zero FM input for metallic and bell timbres without pitch drift
  • Hard sync input for harmonically rich timbred sweeps
  • PWM knob and dedicated PWM CV input for pulse width modulation
  • Redesigned temperature compensation circuit for voltage and temperature stability
  • Open-source hardware
  • Designed and assembled in Barcelona by Befaco
  • Eurorack 3U format, 8HP

Controls & Jacks (21)

  • Octave— Large 10-position rotary switch that selects the base octave/footage. Positions: 32", 16", 8", 4", 2", 1", 1/2", 1/4", 1/8", 1/16". The 8" p
  • PWM— Pulse Width Modulation control. Sets the pulse width of the pulse/square wave output. Center position produces a perfect square wave (50% du
  • Even— Signature output producing waveform with only even harmonics (2nd, 4th, 6th, 8th...). Creates distinctive hollow, clarinet-like timbre.
  • Saw— Sawtooth/ramp wave output. Bright, harmonically rich waveform containing all harmonics. Classic subtractive synthesis source.
  • Tune— Fine tune control with range of approximately -7 to +7 semitones. Center position is in tune with selected octave.
  • PWM CV— CV input for pulse width modulation of pulse output. Modulate with LFO for classic PWM animation effects.
  • Pulse— Pulse/square wave output. Width controlled by PWM knob and PWM CV input. At 50% width is square wave with odd harmonics only. Varying width
  • H.Sync— Hard sync input. Rising edge detected restarts oscillator waveform from beginning of cycle. Creates harmonically rich timbres tracking sync
  • Sine— Pure sine wave output. Fundamental frequency with minimal harmonic content. Useful for clean bass, FM carrier/modulator, and sub-oscillator
  • Triangle— Triangle wave output. Soft, mellow waveform with only odd harmonics at rapidly decreasing amplitudes. Useful for gentle sounds and modulatio
  • FM— Linear frequency modulation input for through-zero FM. Apply audio-rate or modulation signal for FM synthesis. Enables true through-zero FM
  • Octave— Large 10-position rotary switch that selects the base octave/footage. Positions: 32", 16", 8", 4", 2", 1", 1/2", 1/4", 1/8", 1/16". The 8" p
  • V/Oct 2— Second 1 volt per octave input, summed internally with V/Oct 1.
  • V/Oct 1— 1 volt per octave pitch tracking input. Connect keyboard, sequencer, or CV source to control oscillator pitch. Tracks with 1 cent precision
  • V/OCT— 1 volt per octave pitch tracking input. Connect keyboard, sequencer, or CV source to control oscillator pitch. Tracks with 1 cent precision
  • V/OCT (2nd)— Second 1 volt per octave input, summed internally with V/Oct 1.
  • Saw Output— Sawtooth/ramp wave output. Bright, harmonically rich waveform containing all harmonics. Classic subtractive synthesis source.
  • Even Output— Signature output producing waveform with only even harmonics (2nd, 4th, 6th, 8th...). Creates distinctive hollow, clarinet-like timbre.
  • Sine Output— Pure sine wave output. Fundamental frequency with minimal harmonic content. Useful for clean bass, FM carrier/modulator, and sub-oscillator
  • Triangle Output— Triangle wave output. Soft, mellow waveform with only odd harmonics at rapidly decreasing amplitudes. Useful for gentle sounds and modulatio
  • Pulse Output— Pulse/square wave output. Width controlled by PWM knob and PWM CV input. At 50% width is square wave with odd harmonics only. Varying width

How-To Guides

  • Basic Pitch Setup
  • Classic PWM Chorus Animation
  • Through-Zero FM Bell Tones
  • Hard Sync Harmonic Sweep
  • Even Harmonics Hollow Timbre
  • Dual V/Oct Sum for Interval Tracking
  • Pure Sub-Octave Bass
  • Detuned Unison Pair for Thickness
  • LFO FM Vibrato and Pitch Wobble
  • Live Octave Sweep Performance

Explore the interactive Even VCO panel on BleepDex — tap any control to learn what it does.

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