Synthrotek ‘Super Stoked’ To Intro Mattson Eurorack VCO Module


Synthrotek’s Steve Harmon says he’s ‘super stoked’ to release their new MST VCO Eurorack module.

Why’s he super stoked? Because it completes Synthrotek’s MST line, one of the only complete Eurorack monophonic voices that’s available in both kit and complete form.

The MST VCO is a 100% analog 6-octave 1V/O trackable precision oscillator with full pulse width and modulation controls and with 5 waveform outputs.

The VCO was the last of the modules needed to make a complete synth voice. Like most of the other modules in the MST line, the VCO was designed by synth legend George Mattson. And it’s available three ways: assembled, as a complete kit, or as minimal kit for the hardcore DIYers.

Here’s the official video demo:


  • Coarse and Fine tuning controls
  • Manual and CV controlled PWM (pulse width modulation)
  • 3-octave selector switch
  • 2 Modulation inputs; MOD1 can be attenuated with MOD 1 AMT knob
  • Pulse Width Modulation input which can be attenuated
  • 1V/O adjustment trimmer for making adjustments
  • 1V/O CV input jack
  • 5 waveform outputs (can be used simultaneously): Sine, Triangle, Sawtooth, Sawtooth +1 octave, Square
  • Frequency range: 2Hz-14.39 Khz (Sawtooth +1: 28.77 Khz)
  • Polarity protection

The Synthrotek MST VCO is available now, priced at $239.99 for the assembled version, $149.99 for the full kit and $39.99 for the panel/pcb minimal kit.

7 thoughts on “Synthrotek ‘Super Stoked’ To Intro Mattson Eurorack VCO Module

  1. In the bottom section it seems to color-code black to be input jacks and white to be output jacks, which is good, except that the CV input is in the white section.

    1. The color scheme isn’t really an indication of inputs and outputs. It is just an aesthetic choice.

      The Envelope module for example divides the two envelopes into white and black. On the filter, all jacks are white.

  2. Great news.

    I’ve just finished building up an LFO, Envelope, Filter, VCA, and Noise/SH from this range.

    They are excellent modules and I can’t find anything to complain about so far. Only issue really is that the knobs are pretty close, but that’s an issue with the Euro format itself and not the MST range specifically.

    Quick to build, worked first time with no problems…and cheap if you go the pcb/panel option and source parts.

    Hell, even buying the full kits is very cheap.

      1. I order pots form Tayda, because I really like the solid shaft alpha verticals they have, and they are cheap. The solid shaft makes a brass insert Davies 1900 knob sit nicely centered. They also have awesome prices on all your headers, sockets, trimmer pots, and switches.

        Jacks are from Erthenvar.

        The knobs, boards, panels, and Euro cables are all available from Synthrotek.

        Almost all of the parts are standard stuff from Mouser. These generally use standard 1/4 watt 5% resistors and ceramic caps. The electrolytics should all be 5mm shorts.

        There are a couple of odd items like Germanium diodes, that can be found at Digikey.

        The filter uses vactrols that Synthrotek also carries.

        Nothing is hard to find…all usual parts sourcing. If you know what you are doing then you can get the parts cost in at 50 to 70 % of kits prices, though you obviously need to order parts to build 5 or 6 at a time to save on shipping.

        That said, the kit prices are a good deal if you don’t want to bother with it.

        If you have a question on a specific part, let me know and I can point you in the right direction.

  3. One other note…I got a wrong panel pcb with my VCA but Synthrotek had a replacement to me very, very quickly. Patrick at Synthrotek is top-notch customer support.

    BE SURE you check the layout pictures and silk screen on your boards, and don’t just rely on the name/serial # written on them.

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