Microdesignum MIDI Agente Relay Loop 8L4R1D

The Microdesignum MIDI Agente Relay Loop 8L4R1D is a configurable MIDI switcher for guitar effect loops and amplifier channels, built into a 1U aluminum rack box¹. It switches up to eight guitar effect loops, up to four channels on an amplifier, and includes a preamp (buffer) in the signal path¹. For a player running a MIDI-controlled rig, it is the box that puts every pedal and amp channel change under one Program Change message from a foot controller.

The name spells out the configuration: 8 loops, 4 switch relays, 1 display. Each of the 128 program numbers (1 to 128) holds any combination of loops (1 to 8) and switches (A to D), plus the preamp relay¹².

Eight loops, four amp channels and a preamp

The eight effect loops each have their own Send and Return connections for pedals, and the four switch relays (A to D) connect to the amplifier's channel-switching jacks. The preamp is a buffer, which keeps the guitar signal strong at the start of a long switched chain¹.

The unit has two MIDI inputs, one on the front panel and one on the rear. The signals from both are merged in software, so both can be used simultaneously without risk of damage; data arriving at the front MIDI IN passes to the front MIDI OUT, and rear MIDI IN data passes to the rear MIDI OUT¹.

Programs, editing and MIDI response

The looper responds to incoming Program Change, Control Change or Note On messages, and resends all data from MIDI IN to MIDI OUT so other MIDI devices can be controlled from one source². The default response is to a chosen Program Change command, but individual relays can be set to respond to separate Control Change or Note On commands instead¹.

Editing works two ways: in edit mode using the display, or from a computer with the MIDI Config application, which runs directly in a web browser and requires the Jazz Plugin¹. On the front panel, the Program↓ and Program↑ buttons select the program number to use or edit (1 to 128), and the buttons for the individual relays (1 to 8, A to D and Preamp) set the required combination of loops and switches for that program².

On the related 4L2R1D, the manual documents the deeper editing options that the family shares: each loop or switch can be assigned its own Control Change number (0 to 127) 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 Save; the default is no Control Change assigned. A Channel setting chooses the receiving MIDI channel, values 1 to 16 or all (ALL), and a PC range setting switches the display of Program Change values between technical format (0-127) and user format (1-128), affecting only the display, not what is sent⁴⁵.

Other loop and relay versions

Microdesignum builds the Agente Relay Loop family in several sizes, so a player can match the switcher to the rig. The 8L4R1D sits at the top of the loop-count range alongside its siblings⁶³¹:

The MIDI Agente Relay Loop is the family's base product page, and the 4L2R1D is the compact four-loop, two-relay version in a 256×40×80 mm aluminum box without a preamp⁸. For players who need amp and effect relay switching without audio loops at all, the MIDI Agente Relay Plus is a MIDI-controlled relay switcher for guitar amplifiers and effects whose relays (in 4, 6 or 8-relay versions) can switch amplifier channels¹⁰, and the MIDI Agente Relay Uno is a further variant in the range. A loop switcher of this type, the MIDI Agente Relay Loop 8L4R, was used in the rack of a custom pedalboard system Microdesignum built in 2019¹¹.

The 8L4R1D Plus variant

An extended variant, the MIDI Agente Relay Loop 8L4R1D Plus, adds a Hi-Z preamp compared with the base variant³. It is described as an extended mono MIDI switcher for eight guitar effect loops and four amplifier channels with preamp, in a 1U aluminum rack box measuring Rack 1U (482×40) × 80 mm, with 8 loops, 4 relays with TRS connectors, 2 MIDI ports (front and rear), 1 display, and a preamp³.

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