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Quad Precision VCO

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A-111-4 contains four precision VCOs and has individual controls, inputs and outputs for each VCO available as well as a common control and output unit. After all the A-111-4 is very similar to four A-111-3 without LFO mode but built in output mixers for the three waveforms, and a master unit for all four VCOs.


Controls, inputs and outputs for each of the four VCOs:

  • 1V/Octave CV input

  • Octave switch (+1 / 0 / -1 octave)

  • Tune control (range internally adjustable by jumpers: ~ 2 semitones / ~ 1 octave / ~ 4 octaves)  

  • Modulation CV input

  • Modulation destination:

    • upper position: exponential frequency modulation (XM)

    • lower position: linear  frequency modulation (LM) or pulsewidth modulation of the rectangle (PM), selectable via internal jumper

  •  Frequency Modulation (FM) or Pulsewidth Modulation of the rectangle (PWM)

  • Modulation intensity

  • Triangle output

  • Sawtooth output

  • Rectangle output (about 50% without external PWM)

  • Sync input (hard or soft sync internally selectable via jumper, CEM3340 hard sync type)

  • min. 10 octaves range (with appropriate external CV)

  • CEM3340 based VCO (triangle core)

  • each VCO has it's own separate internal +/- power supply for each for best stability and the prevention of unwanted synchronisation of the VCOs

Controls, inputs and outputs of the master section:

  • 1V/Octave CV input

  • Octave switch (+1 / 0 / -1 octave)

  • Tune control (range internally adjustable by jumpers: 2 semitones / 1 octave / 4 octaves)  

  • Frequency Modulation CV input (FM)

  • FM intensity

  • Triangle sum output

  • Sawtooth sum output

  • Rectangle sum output

  • as soon as the single waveform output of a VCO is patched this waveform of the VCO in question is removed from the sum (this function can be turned off for each single output socket by means of solder brigdes on the pc board, i.e. the sum contains then all signals independent of the patching of the single output)

  • CV output (outputs the sum CV that is used to control all four VCOs)

  • bus CV (selectable via jumper)

Typical applications:

  • fat sounding monophonic VCO with the possibility to adjust any intervals

  • paraphonic patches in combination with the polyphonic CV interface A-190-5 (all four VCOs processed by one VCF/VCA)

  • full polyphonic patches in combination with the polyphonic CV interface A-190-5 and four complete VCF/VCA sections  

  • complex VCO patches with up to four VCOs by means of the frequency modulation features (exponential an linear) and the sync functions

The following document shows the positions and functions of the jumpers and trimming potentiometers of the module: A111_4_trimming_potentiometers_and_jumpers.pdf
Pay attention that faulty adjustments caused by the user are not covered by warranty. In this case the working time required to re-establish the correct adjustment has to be charged. This warning does not apply to the change of the jumper positions. 

Technical remarks:

The module is based on the CEM3340 circuit. The hard sync of the CEM3340 works different compared to most other VCOs. The excerpt from the data sheet shows the details:


The CEM3340 type of hard sync is also explained in the A-111-1 user manual on page 9: A111_man.pdf

Breite/Width:18HP / 90.3 mm
Tiefe/Depth: 40 mm (gemessen ab der Rückseite der Frontplatte / measured from the rear side of the front panel)
Strombedarf/Current: +120mA (+12V) / -100mA (-12V)


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