Synthrotek is pleased to offer a complete line of eurorack synthesizer modules, power, cases and accessories in both complete units kits and panels & pcbs. We now offer a very complete analog modular monophonic voice with many accompanying utility modules. This new complete voice is the product of a collaboration with synth guru George Mattson, who now joins us in releasing our new MST (Mattson – Synthrotek) line of premium modules.



The MST Low Pass Filter is a precision analog dual slope output 2 & 4 pole filter. Simultaneous -12 DB and -24 DB outputs with CV control over all parameters. Can be used as a 1V/O sine wave oscillator


Manual control of cutoff frequency

Manual Control of Resonance (Q)

1V/O input for clean sine wave output

CV Frequency input w/ attenuator

Resonance CV input w/ attenuator

Audio input

Simultaneous -12 db and -24 db/octave outputs


Current draw: V+ max 23.5mA, V- max 15.5mA

Width: 6HP  Depth: 3.5cm (1.75 in)


MST VC Low Pass Filter 1v/o Tuning Instructions


Things you will need:

  • 1v/o cv source (midi-cv with a keyboard, oscillator with a Hz readout)
  • The MST VC Low Pass Filter
  • Patch cables
  • Chromatic tuner (we use Pitchlab Pro, its free for Android and IOS)
  • Small flathead screwdriver

Patch Setup:

  1. Plug your 1v/o source into the 1v/o jack in the MST VC Low Pass Filter
  2. Plug the -24db output of the filter to an amp or speakers, something where you can hear it.
  3. Turn All Knobs to the Full CCW position.

Tuning Instructions:

  1. Set your 1v/o source to 0v, which we will call C1.
  2. Turn the Resonance knob all the way CW.
  3. Slowly turn the Cutoff knob CW until you can hear the Filter self oscillating, and keep turning until the pitch reads ~32.7 Hz, C1.
  4. Set your 1v/o source to 1v, which will be C2.
  5. Flip the Filter over and adjust the trim pot until the pitch is ~65.4 Hz, C2.
  6. Set your 1v/o source to 2v, and check that the filter is now at C3, 130.8Hz.

Congratulations on your tuned Filter!


  1. Chris says:

    i don’t really understand how to set the 1v/0 source to 0, 1 or 2v.
    Could you give me more details before i decide to buy it in kit?
    thanks a lot

  2. Steve Harmon says:

    Hey Chris,
    There’s a couple ways to achieve particular voltages for calibration. I use a multimeter to check the voltage regardless of tactic. You can use a midi to converter and focus on the proper note (A C1 will be 0v, C2 is 1v, C3 is 2v, etc..) to just send a static voltage. If you have an attenuverter that just puts out a static voltage, measure the cable you’d be plugging into the filter and get it to your desired voltage, then do you filter adjustments. A sequencer without a clock making it run is also a great way to get a steady voltage that can easily be adjusted. Let us know if you hit any snags or want any clarification on the processes and we’ll help out as best we can!

  3. Matt says:

    Is there any way to just get a couple of, I know, boring filter sweeps on a square wave. Just to hear the basic character of the filter. All the bleeps are great and all, but I’d rather hear the tonal character of the filter.

  4. Synthrotek says:

    Good idea! We should certainly add that

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