Microdesignum MIDI Expressione

The Microdesignum MIDI Expressione is an expression pedal with a built-in miniature MIDI controller. Instead of, or in addition to, working as a conventional expression pedal, it converts the position of its potentiometer into MIDI Control Change messages, so it can drive any MIDI-equipped pedal or rack unit that accepts a CC value. Microdesignum describes it as an expression pedal with a built-in miniature MIDI controller with a potentiometer converter¹.

The range includes versions with a microswitch under the toe of the pedal. That switch is sent as its own Control Change message, with the pedal position reported as values from 0 to 127 and the switch state as 0 or 127². Microdesignum positions this for guitar effects such as the Line 6 M13, which has no input for an external switch under the expression pedal¹.

MIDI connections and setup

The pedal carries one MIDI IN and one MIDI OUT for connecting to an effect¹. The MIDI OUT is where the expression and toe-switch data leave the pedal on their way to the controlled device. On the 1F variant the MIDI IN is used only for incoming configuration messages¹; on the 1A variant it does more, described below.

Power is unusually forgiving. The supply can be anything from 6 to 15 V, alternating or direct current, with any polarity, because the built-in MIDI module has its own rectifier and stabilizer¹. That removes the usual center-negative requirement of most pedals and means an AC output from an older supply will also work.

The 1A and 1F versions

The MIDI Expressione line splits into two main circuits, each also sold as a standalone module for building into a customer's own expression pedal¹⁴⁵.

The 1F is built on Microdesignum's smallest MIDI module, the Sardonyx 8 Mikron¹. It is offered both as a complete pedal and as the MIDI Expressione 1F Module, a miniature controller for building into an expression pedal with a microswitch under the toe, a variant Microdesignum also lists as designed for the Line 6 M13³.

The 1A, by contrast, works as a MIDI merger: it safely forwards MIDI messages arriving at its MIDI IN, merged with the messages generated by the potentiometer converter¹. This means a second MIDI source can sit upstream of the pedal and its messages still reach the effect. The MIDI Expressione 1A is a MIDI expression pedal in this configuration⁷, and its module version, the MIDI Expressione 1A module, converts the analog value of an expression pedal's potentiometer to a MIDI Control Change command⁸.

There is also the MIDI Expressione 1A1F, a MIDI expression pedal with a switch under the toe, one analog input, and a built-in MIDI module sending Control Change for both pedal position and switch state². Its module variant, the MIDI Expressione 1A1F module, does the same conversion of pedal value and toe button status to Control Change⁹. Microdesignum states that the 1F1A converter variant is based on the more powerful Sardonyx 20 Direttore MIDI module¹. The standalone modules are sold programmed, with connectors, tested and fully functional⁴.

Configuration: MIDIConfig and SysEx

The MIDI channel and the CC numbers can be changed two ways. One is the MIDIConfig web application, a browser-based configuration interface that sets the MIDI channel and the CC numbers for the toe switch and the expression pedal⁵. The other is a SysEx message, which Microdesignum publishes as:

``` F0 4D 69 63 00 00 00 03 kk cc pp F7 ```

¹

On some versions the MIDI channel can also be changed by DIP switches on the front panel⁵. For a player who just wants the pedal on a different channel, the web interface avoids hand-assembling a SysEx string.

Questions