Microdesignum MIDI Agente Relay Loop

The Microdesignum MIDI Agente Relay Loop is a programmable MIDI switcher for guitar effects and amplifier channels. It responds to incoming MIDI Program Change, Control Change or Note On messages by switching up to 8 loops of guitar effects and up to 4 channels of a guitar amp, and any combination of loops and switches can be programmed onto each of its 128 program numbers¹². It is built by Microdesignum, a Czech maker of MIDI switchers and retrofit MIDI modules, and it sits at the center of a MIDI pedalboard or rack: one MIDI controller can drive the loops, the amp channels and any other MIDI gear from a single source.

The full-featured configuration offers 8 effect loops, 4 switch relays (A to D) for amp channel switching, and a preamp relay¹. Some variants include a Hi-Z preamp and some do not, so the variant matters when comparing listings².

Programs, buttons and modes

At power-on the switcher enters common mode and jumps to its default program, normally program 1, closing the relays set for that program. The default program can be changed through the Default pgm setting, which accepts any value from 1 to 128⁴.

Editing a program follows a short sequence¹⁵:

1. Use the Program down and Program up buttons to select the program number to use or edit (1 to 128).
2. Use the buttons for the individual loops (1 to 8) and relays (A to D and Preamp) to set the required combination.
3. Press the Save button briefly. The display shows SAV and the combination is permanently stored for that program.

The switcher has three modes¹:

• Common mode: the working mode active at power-on, where programs are selected and recalled.
• Global mode: entered by pressing and holding Save (the display shows GLB); it configures MIDI communication, with items selected using buttons 1 to 5.
• Individual mode: assigns a Control Change number (0 to 127) to each loop or switch for individual control, entered by holding that loop's or switch's button for about 5 seconds until the display shows IND, then saved with Save⁵.

One wiring quirk is worth knowing: because of the internal wiring, when a button is pressed in global mode the corresponding loop or switch relay also closes together with its LED⁵.

Global parameters

MIDI input, thru and phantom power

The switcher receives Program Change, Control Change and Note On messages, and dots in the upper part of the display indicate when one has arrived⁴. It resends all data from MIDI IN to MIDI OUT, so other MIDI devices can be controlled from one source¹.

The device provides phantom power on pins 6 and 7 of the MIDI IN and MIDI OUT DIN7 sockets, which lets a MIDI controller be connected with a single 7-pin DIN cable¹.

On the 8L4R1D variant there are two MIDI inputs, one on the front panel and one on the rear, and the signals are merged in software so both inputs can be used at the same time without risk of damage. Data from the front MIDI IN goes to the front MIDI OUT, and data from the rear MIDI IN goes to the rear MIDI OUT⁶. A foot MIDI controller connects to MIDI IN with a five-pin or seven-pin cable⁵.

Amp channel switching and the preamp

The switch relays A, B, C and D can be used for switching the channels of a guitar amplifier; A+B and C+D share a common ground¹. On the smaller variants, the switch relays replace the amp's own footswitches: they are connected to relays and galvanically isolated from each other and from the whole device, generating no signal themselves, only closing two wires⁵. The maker notes that amps with paired channel switching on TRS jacks need an appropriate Y-cable⁷.

Within each program you can switch the preamp on, but only its on/off status is saved, not its gain¹.

Loop and relay versions

The Agente Relay Loop family is sold in several configurations, and Microdesignum states it can fit a variant with exactly the number of relays and connectors a customer asks for, with the price adjusted accordingly⁶.

The 8L4R1D Plus is described by the maker as an extended mono variant of the eight-loop MIDI switcher in a 1U aluminum rack box, for eight guitar effect loops and four amplifier channels with preamp¹⁰. The 8L4R1D can be configured either through its display in edit mode or from a computer using the MIDI Config application, which runs in a web browser with the Jazz plugin⁶.

Related products in the range include the MIDI Agente Relay Plus, a relay switcher without loops for amplifiers and effects, and the MIDI Agente Relay Uno, which can also switch signals other than amp channels. For background on the category generally, see MIDI pedals⁷¹¹.

Questions