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.
