Microdesignum MIDI Agente Relay Plus

The Microdesignum MIDI Agente Relay Plus is a MIDI-controlled relay switcher for guitar amplifiers and effects. Instead of stomping an amp's mechanical channel switches, you send it a MIDI command (Program Change, Control Change or Note On) and it closes or opens its relays to change channels, and it can switch other signals besides amp channels¹². It is built around a display and control buttons, so you can set up and store relay combinations on the unit itself².

The relays are the key to what it does: up to 8 relay outputs on 6.3 mm jacks, wired to your amp's channel switching jacks the way the amp's own footswitch would be². Each of the 128 programs stores any combination of relays, saved permanently in memory².

A MIDI-controlled relay switcher

The Relay Plus sits in the MIDI chain and reacts to incoming data by switching its relays according to the MIDI command it receives². Microdesignum positions it as a replacement for mechanical switches used to control guitar amplifiers². Because the relays are simple contact closures, they behave like the amp's own footswitch: no special jack or protocol on the amp side, just a cable from the relay output to the amp's switching input.

The relay outputs are flexible in how they are wired. Each relay can be brought out individually as a mono jack, or in pairs (1 and 2, 3 and 4, 5 and 6, 7 and 8) as stereo jacks, so one TRS cable carries two relay contacts².

The unit also works as a MIDI hub: it resends all data from MIDI IN to MIDI OUT, so other MIDI devices can be controlled from one source¹. That means a single foot controller can run the Relay Plus and, chained through its MIDI OUT, other switchers or MIDI pedals in the same rig.

Within Microdesignum's range, the Relay Plus is the pure relay switcher. The MIDI Agente Relay Uno is a smaller multi-switcher that controls up to 7 relays from Program Change or Control Change commands, sold as a bare module, a boxed miniaturized unit, or a 1U rack product³. The MIDI Agente Relay Loop adds effect loops to the same idea: it is a programmable switcher of guitar effects and amp channels, aimed at players who want to control pedal combinations during a live performance with a single press of a foot MIDI controller⁴.

Programs, modes and the Save button

Programming happens on the unit itself. The Program down and Program up buttons set the program number you want to use or edit, from 1 to 128¹. You then set the relay combination for that program and store it:

1. Select the program number with the Program down and Program up buttons (1 to 128)¹.
2. Set the required combination of relays¹.
3. Shortly press the Save button. The display briefly shows SAV and the combination for the selected program is permanently stored in memory¹.

Holding the Save button instead takes you into the global menu, where MIDI communication is configured⁵⁶⁷. The switcher works in three modes: common mode, which it enters whenever power is switched on; global mode, the configuration menu reached through the held Save button; and individual mode, where a Control Change number is assigned per relay¹.

One global parameter worth knowing is Default pgm, the program number set when the device is switched on, with values 1 to 128. It appears only on models with more than 4 relays¹.

Power and connections

The Relay Plus runs on a wide power range: 7 to 15 V, AC or DC². Boxed versions include a power adapter, with voltage and polarity depending on current stock; bare modules ship without an adapter².

The MIDI side is one MIDI IN and one MIDI OUT². Both DIN sockets carry phantom power on pins 6 and 7, which lets a foot MIDI controller connect with a single 7-pin DIN cable and draw its power from the switcher, with no separate supply at the board¹.

Versions: module or 1U rack

The Relay Plus comes in two forms²:

• Bare module: no enclosure, for building into a controlled device such as an amplifier, configured to the customer's wishes².
• 1U rack box: the module built into an aluminum rack box with color printing².

For players comparing within the family, the Relay Loop line follows the same pattern, with variants such as the MIDI Agente Relay Loop 4L2R1D and the larger MIDI Agente Relay Loop 8L4R1D adding effect loops and, on some variants, a Hi-Z preamp⁴.

Questions