Frequency Central – PRODUCT – Full DIY Kit

£162.50 (Excl. VAT)

Analog Synth Voice based on XVCO2 / Raging Bull VCF / System X Envelope

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Product is a full featured modular synth voice in 26HP which can be used without any patching or as the heart of a modular system. Each component part is fully modular, but also features pre-patched normalised signal paths for fast set up of new and exciting sounds.

Product features a motherboard on which all pots, switches and sockets are mounted, this is also where the pre-patched normalising happens. So the onboard LFO is available for both FM and PWM of the VCO. The three VCO waveforms are available at the three VCF signal inputs. 1V/oct input, LFO and ADSR are available at the three VCF signal inputs. By some cunning switching, the VCA can be operated by either ADSR or gate input, alternatively it can be set to drone position. Also available are signal outputs from the LFO and noise generator. All pre-patched connections can be broken simply by inserting a jack into the relevant socket.

Product is a combination of three individual Frequency Central modules:

  • XVCO TWO (based on the Roland System 100M)
  • Raging Bull 3.0 VCF/VCA (based on the Moog Taurus Mk I VCF and VCA)
  • System X Envelope (Based on the Roland System 100M)
  • Onboard LFO for PWM and FM
  • Onboard noise source

To simplify the building process, there are three daughterboards that plug into the Product motherboard: the VCO daughterboards, the VCF/VCA daughterboard, and the ADSR/noise daughterboard. First you can build and calibrate the VCO, plug it into the Product motherboard, get it running and have some fun with it. Then build the VCF/VCA daughterboard, and add it to your expanding modular synthesiser. Finally you can build the ADSR/noise daughterboard, and your synth is complete.


Roland 100M VCO adapted to Euro. The hard-to-find/easy-to fake ua726 diff pair has been replaced with a UL1111.

  • A six position rotary switch for octaves gives plenty of range. The PITCH pot is fine tune.
  • Individual outputs for ramp, square and triangle – an improvement on the original.
  • built in chip heater to keep you nice and stable in this topsy turvy World!
  • Onboard LFO! Yes that’s right, an onboard LFO (thanks MC202) for introducing FM and/or PWM. Super!


Based on the legendary Moog Taurus Mk I VCF and VCA. It has a lovely, thick Moog-like quality, which is further enhanced by the drive you can get out of its VCA at higher settings. A big part of the sound of the Taurus was the way in which the VCF interfaced with the VCA, so on Raging Bull the VCA is always in the audio path. A toggle switch allows you to select ‘always open’ or CV control of the VCA

Build Document – Assembly Guide

Current Draw:

  • 75ma +12V
  • 45ma -12V
  • 0ma +5V

Additional information

HP Size

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