Eurorack dual analog VCO 16HP module with through zero FM - Precision tracking triangle core

Dual analog triangle core voltage controlled oscillator (VCO) 16HP Eurorack module with through zero FM modulation based on SSI2130 ICs; features precision analog exponential converters, triangle oscillator cores, waveshapers as well as high quality voltage controlled amplifiers for wave mixing.

Each VCO in the module outputs sine, triangle, saw and square/pulse waves,also voltage controlled mix of them with sub oscillator an octave below controlled with integrated crossfader mixer.

Both oscillators can be modulated with exponential and linear FM, as well as through zero FM/PM, wave shape and pulse width CV. To ease modulation for each oscillator we have added separate sine outputs with variable gain controlled with modulation knob.

Module also offers master crossfader to mix the outputs of the two oscillators, octave selector switch for each oscillator, as well as knobs for shape, pulse width, pitch and fine tuning. Module is designed using precision voltage reference and other high quality components to achieve +/-1ct (+/-0.01 semitone) tuning across 10 octaves- well below human ear pitch sensitivity which is around 3-5ct.

All inputs and outputs are ruggedized, protected when signal is connected to the wrong input - able to handle rail to rail voltages +12V..-12V.

All potentiometers are precision Alpha variety, module is made using high quality electronic components, features rubber knobs with soft touch for easy grip and pleasant tactile feedback.

Module is available with and without 1kΩ compensation. Compesation is required when used with pitch CV modules with 1kΩ impedance such as Moog Mother 32, MST '07 Buffered Multiple and others. Doepfer and other new modules have buffered 0kΩ impedance on pitch CV, non compensated version should be used in this case

Revision 2.0: Newer OpAmps and gold plated contacts.

Revision 2.1: Improved Pitch stability, tracking and TZFM precision. Removed octave switch trimmers for easier tuning - instead used precision parts for fixed octave switching accurate within 1ct. Burr-Brown audio opamps on all outputs.

Revision 2.2: octave switch changed from 6 to 8 positions for more modulation options, added startup circuit to prevent VCO lockup on start for those with asymmetric power supplies, modern JFET/CMOS OpAmps - slightly improved accuracy and reduced power consumption, extra components for accurate sine outputs with virtually no offset, high end trimmers for even more accurate pitch tracking.

• Power consumption: +12V - 175mA, -12V - 150mA, +5V - 10mA
• Module width: 16HP
• Module depth: 3.8 cm
• Modulation: 1 volt/octave - +5V..-5V or 0..10V
• Tuning precision: 10 octaves - +/-1ct (+/-0.01 semitone)
• Frequency range: 0.5Hz - 20kHz
• Noise level: -90dB
• Input impedance: 100kΩ
• Output impedance: 1kΩ 0.1%