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

£95.00 (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.

Out of Stock


The God’s Box ‘Humpback’ kit is produced exclusively in collaboration with Thonk. This kit includes everything you need to build the module apart from tools and solder. The module is 8hp wide and is skiff friendly; 38mm deep. The kit is packed to the same high standards customers have come to expect from all Thonk kits.


  • Aluminium 8hp Eurorack panel – High Quality two colour Aluprint process
  • Red PCBs with ENIG gold traces
  • All electronic components required including matched transistor pair
  • Genuine and new/unused Rochester CA3080AE chips
  • Knobs, power cable, M3 rack screws


The Humpback multimode voltage controlled filter is a 2-pole, CA3080 based implementation of the classic state variable architecture. The controls of the filter are as follows:

  • 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-resonance control is included and is hot-rodded to allow self-oscillation. In self oscillation the filter will produce a sine wave output.

Build Documentation

BUILD DOC, SCHEMATICS, BOMhttp://thonk.co.uk/documents/gbox/humpback/

Muffwiggler Build thread – https://www.muffwiggler.com/forum/viewtopic.php?p=1949692

Additional information

HP Size

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