The System80 810 is a 30 HP Eurorack module consisting of a standard subtractive analog synthesizer voice: Voltage Controlled Oscillator (VCO), Voltage Controlled Filter (VCF), and Voltage Controlled Amplifier (VCA).  While not strictly a clone, the design of each sub-module is inspired by the golden age of Japanese analog, featuring elements of the System 700, System 100m,  and the Jupiter-8.  Add some modulation and an envelope generator to create a complete patchable analog voice with a distinctively vintage character.

VCO

• Discrete Voltage Controlled Oscillator with temperature compensated exponential converter
• 1 V/octave tracking over 8 octaves
• Sync input with weak and strong oscillator sync modes
• 1 V/octave CV input + two attenuated exponential CV inputs for pitch/frequency modulation
• Five position octave range switch
• Selectable waveform output: Pulse, Ramp, Triangle, or Sine
• Pulse Width Modulation CV input

VCF

• Cascaded OTA design inspired by classic Roland topologies with selectable 12 or 24 dB response
• self-oscillating with 1 V/octave tracking (3-4 octaves, normalized to VCO KYBD CV input)
• VCO output and sub-oscillator normalized to two log attenuated inputs
• Two frequency CV inputs, one unipolar and one bipolar
• Voltage controlled resonance

VCA

• Traditional single OTA design
• Three log attenuated audio inputs with IN 1 normalized to VCF output
• Two CV inputs with selectable exponential or linear response