Please note: in order to use the Expander, your MST MIDI to CV Converter must have code version 1.3. If you have an older version of the software on your Converter, you will need to purchase a new PIC18 chip for the Converter in order to use it with the Expander; the software is not available for download. The version is written on the PIC18 chip itself, you can see it if you pull your module out of your case and look at the back.

The MST MIDI to CV Expander module is a tiny but extremely powerful expansion module for the . The Expander includes an arpeggiator and allows you to have additional CV, gate, velocity, modulation and aftertouch outputs on a separate MIDI channel. You can also set it to the same MIDI channel as the Converter and use one of the three note priority selections, which will allow you to do duophony/pseudo-polyphony. You can daisy-chain Expanders together to add even more channels.

The Expander really shines when it is used with a DAW. Multiple Expanders can be set to different MIDI channels in any sequencer (like Ableton for example), making live performance with your Eurorack simple.

The Expander connects to the MIDI to CV Converter using an  (included).

  • Three note priority modes: high note, low note or last note
  • Arpeggiator modes: Forward, Ping-pong, Random, and Order Played ()
  • Arpeggiator latches when a sustain pedal is held on a MIDI keyboard (once the arpeggio is established)
  • Control the arpeggiator with a modular or MIDI clock
  • Manual MIDI Reset Button
  • Volts-per-octave trimmer accessible from the front panel
  • Velocity, Modulation and Aftertouch CV output jacks function independently but can be used simultaneously
  • Pitch CV and gate outputs
  • Select MIDI channels 1-16 with an internal DIP switch
  • Gate / Note Priority LED indicator
  • Polarity protection

  • Current draw:
    • +12V: 55mA
    • -12V: 15mA
  • Module Depth: 48mm
  • Width: 2HP
Please note: the Expander will not work without the .

Product Specs

Brand New (New)
MST MIDI to CV Expander
Made In
United States


About The Seller

Joined Feb 2016
Moscow, ID, United States


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Ships from Moscow, ID, United States to:

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Shipping time -- Orders usually ship within 1 business day.

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Return Policy

Return Window

This product can be returned within 30 days of receipt.

General Terms

Items must be returned in original, as-shipped condition with all original packaging and no signs of use. Buyer assumes responsibility for all return shipping costs unless the item was not received as described.


Buyer receives a full refund in their original payment method less any shipping costs and a 5% restocking fee.

Special Conditions

We accept returns on all products in their original packaging. Kits and PCBs can also be returned, but ONLY if they are not soldered/built. There is a 5% restocking fee on all returns.


If you are missing a component from your kit, please email us immediately. Our kits are handpicked and errors, although rare, can occur (we're only human). We'll send you out what you need immediately and we'll make sure to hook you up.

If you are having any difficulty building your kit, or if you have any questions, feel free to call us or email us, we are happy to help!

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Moscow, ID, United States
Joined: Feb 2016

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Synthrotek MST MIDI to CV Expander
+ $4 Shipping