High End VCO

Module A-111-1 (VCO 2) is a voltage controlled oscillator. The VCO has a range of about 12 octaves, and produces four waveforms simultaneously: pulse (rectangle), sawtooth, triangle and sine waves. The VCO's frequency is determined by the position of the range switch, tune and fine tune controls, and the voltage at the two pitch CV inputs, CV 1 and CV 2. Footage (the octave of the fundamental) is set by the Range control, which has seven octave steps. The Tune control is used for coarse tuning, and the Fine control for fine tuning of the VCO pitch. The A-111 can be modulated by both exponential and linear FM (frequency modulation). You can control the pulse width of the square wave either by hand, or by voltage control - Pulse Width Modulation, or PWM for short.

The A-111 has inputs for Hard Sync and Soft Sync.

For more detailed information please look at the English user's manual: Doepfer A-111

Technical remark:

The sine is derived from the triangle by a simple diode-based converter and the sine shape is not perfect (nothing but a rounded triangle). For a perfect sine wave the quadrature LFO/VCO A-143-9 is recommended (or a self oscillating VCF).

As the special circuit CEM3340 used in this module is no longer available the module has to be discontinued. Sale while stocks last !

Note: the Curtis CEM3340 is back in production as of 2018.


  • 40 mA +12V
  • 40 mA -12V
  • 0 mA 5V
  • 65 mm deep
  • Ø 4.30 (27 Votes) Average Rating

This Module is discontinued.

$349 Price in €
14 HP Oscillator
submitted Oct 6th 2012, 13:36 by MacroDX | last Change Apr 30th 2018, 16:14 by lpgeffen