Doepfer A-110 VCO
Four-waveform analog VCO with PWM and hard sync
8 HP Eurorack module
The Doepfer A-110-4 is a Thru-Zero Quadrature VCO that outputs pure sine and cosine waveforms simultaneously. Unlike most VCOs that derive sine waves from sawtooth via waveshaping, the A-110-4 uses a true sine/cosine oscillator core, producing exceptionally clean waveforms with minimal distortion. The "thru-zero" capability means the oscillator can pass through zero frequency and continue in reverse, enabling FM synthesis spectra impossible with conventional VCOs. It features both exponential (XTune, 1V/Oct, XFM) and linear (LFrq, LFM) frequency control sections. The linear section is key to thru-zero operation: sweeping LFrq through center causes the waveform to decelerate, stop, and reverse direction. Output level is approximately 10Vpp. Width: 8HP, current: +90mA/−30mA.
Features
- Four simultaneous waveform outputs: sawtooth, square, triangle, sine
- Frequency range of approximately ten octaves
- Hard Sync input for locking slave VCO to master VCO
- Two CV inputs (CV1 and CV2) summed for pitch control, following 1V/octave standard
- CV1 normalled to internal System Bus for keyboard tracking without patch cables
- CV2 with attenuator knob for FM depth control
- Manual Pulse Width control for square wave shaping
- Two PWM voltage control inputs (PW CV1 and PW CV2) summed, PW CV2 level adjustable via attenuator
- Range switch with five octave/footage positions
- Fine tuning Tune knob with approximately plus/minus half octave range
- Exponential FM response
- Warm-up time of approximately 20 minutes for full tuning stability
Controls & Jacks (10)
- XTune
- XFM Amount
- LFrq
- LFM Amount
- 1V/Oct In
- XFM CV In
- TZ Control LED
- LFM CV In
- Sine Out
- Cosine Out
How-To Guides
- Basic VCO Keyboard Tracking Setup
- LFO Pulse Width Modulation
- LFO Frequency Modulation Vibrato
- Hard Sync Timbral Sweeping
- Two-Oscillator Detuned Chorus
- Audio-Rate FM Bell and Metal Tones
- Sub-Octave Layering with Divider
- Soft Flute or Vibraphone Tone
- VCO Sync Tone Colour Morphing
Explore the interactive A-110 VCO panel on BleepDex — tap any control to learn what it does.
