Zlob Modular – Dual VCO – Full DIY Kit


Powerful & stable dual VCO/LFO in a small footprint

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SKU: Kit_Zlob_Dual_VCO Categories: , , , , ,


The Dual VCO is a 4hp dual voltage controlled analog oscillator. Each VCO has square, triangle, and sine wave out, coarse and fine tuning controls, a control voltage input, and a switch for selecting between exponential or linear CV in. When a control voltage is inserted, the fine tune control becomes an attenuator for the incoming voltage. In exponential mode, when the attenuator is fully clockwise, the VCO will track around 5 volts per octave.

Note that there are two main quirks with this 8038 oscillator design:

Below 300hz the waveform symmetry is slightly off. Triangle waves get a little uneven in the LFO range, the sine is not completely perfect to begin with in the bottom trough and in the LFO range it slopes slightly, also the square turns more trapezoidal above 1khz. The VCO also doesn’t track 1 volt per octave perfectly – usually the 2nd and 4th octave will be a couple cents off. Other than these idiosyncrasies, it is a powerful, stable dual oscillator in a small footprint with no cross talk between oscillators. It’s great for: drones and beating sine or triangle waves, cross modulating itself for interesting clocks/LFOs, creating complex waveforms/timbres through lin/exp frequency modulation.

Dual VCO Build Document – Assembly Guide

(pcbs come with smd matched transistors pre-soldered)


  • Each VCO runs from 0.2 hz (5 seconds a cycle) up to 18k hz
  • Very Stable, Temperature compensated circuit
  • Waveform outputs: 10vpp
  • Width: 4HP
  • Depth: 45mm
  • Current consumption: +12v 20mA, -12v 38mA


Additional information

Weight 0.102 kg

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