God’s Box ‘Humpback’ Filter. FULL DIY KIT

£105.68 (Excl. VAT)

A full DIY kit for a 2-pole multimode filter reminiscent of the classic ‘SEM’ style state variable VCF. Special features include a hot rodded resonance circuit and increased frequency range.

Latest PCB version – All SMD components are already professionally reflow soldered in – This project requires a small amount of through-hole soldering only.

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The Humpback VCF is a fat 2-pole state variable filter which invokes the classic sounds of the synthesiser ‘golden years’, twisted and mutated to reflect the future. Multi-mode, state-variable topology and ‘hot-rodded’ resonance for self oscillation. Humpback is made with high quality components including silver mica capcitors.

Humpback has a sound all of its own. Low input levels will give you a traditional 2-pole filter sound – warm, but clean. As the filter is driven and resonance increased, the distinctive character of the filter is revealed – a ‘rubbery’ resonance which seems to pluck out harmonics. The MK2 version adds a ‘dirty’ resonance on the bandpass output and a green LED for input level indication.

Humpback – Build Document


  • Filter cutoff – a hardwired DC voltage frequency control
  • CV inputs – two frequency CV inputs are included on the panel and controlled by attenutators.
  • Outputs – lowpass, bandpass, highpass and notch are available simultaneously
  • Signal input – one signal input is available on the panel
  • Resonance – variable control is included and ‘hot-rodded’ to allow self-oscillation. In self oscillation the filter will produce a sine wave output.

Additional information

HP Size