If you’re a guitar player using several effects, amplifiers, switchers, or loopers, MIDI can make your entire rig much easier to control. However, when you first start, terms such as MIDI channels, Program Change, Control Change, MIDI Out, and MIDI Thru can quickly become confusing.
Once you understand the basics, a single footswitch can recall a complete sound, change amplifier channels, switch effects, and control several devices at the same time. In this post, I’ll explain the main MIDI messages and connections in a simple and practical way, helping you build a setup that works reliably.
Connecting MIDI Devices
Most MIDI equipment uses female 5-pin DIN connectors and cables with male plugs. Connect MIDI Out to MIDI In or MIDI Thru to MIDI In. Compact pedals often use a 3.5 mm TRS MIDI connector. Type A and Type B wiring both exist, so check the device manual and use the correct adapter. The differences are explained in the official TRS MIDI wiring guide.
MIDI Controllers
MIDI controllers include foot controllers, computers, synthesizers, and guitar processors that send messages using buttons, footswitches, sliders, or expression pedals. For a flexible guitar rig, look for a controller with a display, an expression-pedal input, and the ability to send several messages with one footswitch.
MIDI Receiving Devices
Guitar effects, processors, amplifiers, switchers, and loopers that respond to MIDI messages are receiving devices. Some products can both send and receive MIDI.
What Is the Difference Between MIDI Out and MIDI Thru?
MIDI Thru reproduces the messages received at MIDI In. MIDI Out normally sends messages generated by the device itself. Some products can also retransmit incoming messages through MIDI Out using a Soft Thru or MIDI Merge function, but this must be confirmed in the device manual.
If a device has no physical MIDI Thru port, do not assume that MIDI Out will pass incoming data. Check whether Soft Thru or MIDI Merge is supported, or use a dedicated MIDI Thru box.
The MIDI Out on the N-audio 8X7 Amp Cabinet Switcher and 4X4 Amp Cabinet Switcher retransmits incoming MIDI messages and also sends the SysEx messages used to control the FX-Loop Extensions.
Connecting Multiple MIDI Devices
Place the MIDI controller at the beginning of the chain. Connect its MIDI Out to the first device’s MIDI In, then connect each MIDI Thru to the next MIDI In. If you need several parallel outputs, use an active MIDI splitter.
MIDI Channels
MIDI channel messages can use any of 16 channels on each MIDI port. The controller and receiving device must be set to the same channel to communicate.
Different channels allow you to control several devices independently. For example, if you have two identical delay pedals set to the same MIDI channel, both may respond to the same messages. Setting one delay to Channel 1 and the other to Channel 2 allows your controller to change their presets and parameters separately.
Some devices offer an OMNI mode that receives messages on all 16 channels. This is useful for testing or simple rigs, but separate channels provide better control in more complex setups.
Program Change (PC)
Program Change messages are commonly used to select presets, amplifier channels, and looper memories. MIDI provides 128 program values, numbered from 0 to 127. Some devices display them as 1 to 128, so MIDI program value 0 may appear as Preset 1. This is simply a one-number display offset.
Control Change (CC)
A Control Change messages are similar to the Program Change messages but includes an additional data byte called VALUE. While a Program Change message simply selects a program from 0 to 127, a Control Change message contains a controller number from 0 to 127 and a separate value from 0 to 127.
This additional value allows CC messages to control variable parameters such as volume, effect level, or expression-pedal position. For example, CC #7 commonly controls volume, where 0 represents minimum volume, 127 represents maximum volume, and the values in between provide gradual adjustment.
CC messages can also control on/off functions. Some devices interpret values 0–63 as off and 64–127 as on. The exact CC numbers and values depend on the device, so always check its MIDI implementation chart. A reference list is available on the MIDI Association CC page.
Note On Messages
A Note On message contains a note number from 0 to 127 and a velocity value. Values from 1 to 127 represent playing intensity, while velocity 0 is treated as Note Off in MIDI 1.0. These messages are mainly used by keyboards and drum controllers, although some guitar devices also use them as triggers.
SysEx Messages
System Exclusive (SysEx) messages carry device-specific data beyond standard PC and CC functions. They can be used for patch transfers, settings, firmware updates, and custom control. The N-audio 8X7 and 4X4 use SysEx messages to control their FX-Loop Extensions.
How to Control Your Devices
Start by reading the MIDI implementation section of the device manual. Most guitar equipment uses either a MIDI Learn function or fixed message assignments.
MIDI Learn: Put the desired preset or function into Learn mode, then send a supported PC or CC message from your controller. Some devices recognize only the first supported message in a sequence, so check the manual when using multiple commands.
Fixed message control: The manual lists the exact MIDI channel, message number, and value required for each function. Program your controller to send those messages.
Troubleshooting MIDI Problems
Most MIDI problems are caused by either the physical connection or an incorrect message setting. Start with the simple things: confirm that MIDI Out is connected to MIDI In.
Many MIDI devices have an activity LED that flashes when a message is received. This can be used as a simple MIDI tester. If the LED does not flash, the problem is probably related to the cable, adapter, MIDI output, or physical connection. The N-audio 8X7 and 4X4 amp switchers include this type of MIDI activity indicator.
If the activity LED flashes but the device does not respond, the physical connection is probably working. Check that both devices use the same MIDI channel, then verify the message type, PC or CC number, and CC value.
When the problem is still unclear, use a MIDI monitoring program such as MIDI-OX to see exactly which messages your controller is sending. This quickly reveals incorrect channels, unexpected message sequences, or missing values.
Useful Links
- Read my article about designing MIDI In and MIDI Out circuits.
- Visit the official MIDI Association website for specifications and reference tables.
- MIDI-OX for Windows is useful program for monitoring, filtering, and sending MIDI and SysEx messages from your computer.
Summary
Start with something simple: set both devices to the same MIDI channel and use a Program Change message to select a preset. Once that works, add Control Change messages and more devices. If something does not respond, compare the MIDI sections of both manuals and check the messages sent by your controller.
Niki Hristov