Microdesignum MIDI Expressione 1A

The Microdesignum MIDI Expressione 1A is a MIDI expression pedal from Czech maker Microdesignum. Instead of sending an analog signal down a TRS cable like a conventional expression pedal, it has a miniature MIDI controller built in that converts the pedal's position, the analog voltage on the potentiometer, into MIDI Control Change messages¹. That means it can drive any MIDI-equipped effect that accepts expression data, without needing a dedicated expression input on the effect itself.

Microdesignum sells it two ways: as a complete pedal with the MIDI controller built into a pedal you supply, at 3 600,00 Kč including VAT, or as a standalone programmed MIDI module with connectors, tested and fully functional, at 1 500,00 Kč including VAT¹. The complete pedal weighs 0,700 kg².

From pedal position to MIDI Control Change

The core of the product is a conversion: the module reads the analog value of the expression pedal's potentiometer and turns it into a MIDI Control Change message⁵. In the 1A1F variant, the pedal position is sent across the full MIDI range of 0 to 127, and the range can be calibrated so the pedal's own travel maps onto that full range⁶. The 1A1F also has a switch for calibrating the pedal range to the full 0 to 127 MIDI values⁷.

For a player, this is what makes the pedal useful with rack units and multi-effects that speak MIDI but have no analog expression jack: the pedal becomes a source of continuous controller data on the MIDI chain¹⁵.

The 1A, 1F and 1A1F versions

The MIDI Expressione line comes in three variants, and the differences are straightforward:

The 1A1F is a MIDI expression pedal with a microswitch under the toe of the pedal: the built-in module sends Control Change messages for the pedal position from 0 to 127, and a separate message of 0 or 127 for the switch closure⁷. Its module version is sold as a standalone programmed unit with connectors, tested and fully functional³.

The 1F takes the opposite approach: it has no analog input at all⁸ and is intended for guitar effects such as the Line 6 M13, which lacks an input for an external switch under its expression pedal¹. It is an expression pedal with a built-in miniature MIDI controller and a microswitch under the toe⁸, and its MIDI IN is used only for configuration messages⁸.

Each variant is also sold as a bare module for building into a customer's own expression pedal, described by the maker as an assembled, programmed, fully tested miniature module with connectors⁹.

MIDI and analog connections

The MIDI Expressione pedals carry one MIDI IN and one MIDI OUT, for connecting into an effects setup¹. On the 1F variant the MIDI IN accepts only configuration messages¹.

The MIDI channel and the CC numbers can be changed through the maker's MIDIConfig web application, so the pedal can be set to whatever channel and controller numbers a player's rig expects⁶.

The Sardonyx 20 Direttore module

The 1A's converter is based on Microdesignum's Sardonyx 20 Direttore MIDI module, which uses a 16-bit microcontroller¹. The 1A1F variant is likewise based on the Sardonyx 20 Direttore, while the 1F uses the maker's smallest module, the Sardonyx 8 Mikron¹⁶.

The Direttore sits within a broader family of Microdesignum MIDI modules. Some of these replace a pedal's mechanical footswitch with an electronically controlled relay that responds to MIDI Program Change or Control Change messages¹⁰: for example, the one-footswitch 4PDT relay module maps Control Change number 1 to the relay, with values 0 to 63 switching it off and 64 to 127 switching it on¹⁰. Others let some guitar pedals be controlled by MIDI by electronically simulating the turning and pressing of control knobs or encoders¹¹. The Expressione pedals apply the same idea to a continuous pedal position rather than a switch.

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