Strumbringers midi noob guide

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The Noob's Guide to MIDI

When I first started playing the Axe-FX, I didn't know the first thing about controlling a unit with MIDI. My prior experience had been limited to analog gear and a short foray into modeling with a Boss GT unit. People here were super helpful when I needed it, so I thought I'd return the favor by putting a quick primer together that people can use before they start watching videos / reading manuals / tutorials. The information here won't get you going without your device's manual or tutorials, but hopefully it will help you understand what you're doing and how to achieve what you want to do.

A lot (all?) of this will be obvious to the pros, but I'd have found it very useful when I was getting going :-)

The four things everyone must know:

  1. Most pedal controllers have buttons that do three things (some have a fourth I won't go into):
    • Change presets (i.e. send "Program Change" MIDI messages)
    • Send control messages (a.k.a CC's or Continuous Controller messages)
    • Change the behavior of other buttons (e.g. change banks on the pedal board, make a given button do double duty, etc). The most common type of "change behavior" button cycles through banks on the pedal. In MIDI-controller-land, a bank is a set of messages you have access to without pressing the "Bank up"/"Bank Down" buttons. This is not the same as an Axe-FX preset bank, which is 127 presets. For example, the GC Pro can be set up to have 10 or 4 programs per bank. This varies by pedal board.
  2. The first thing you need to know is how to set up your pedal board to send program change messages. Doing so often means telling it which MIDI Channel your Axe-FX is listening to. There's an excellent tutorial here (sticky) that describes how to do this with a Ground Control Pro, so I won't repeat the instructions. However, basically what happens is that when you press a button, the MIDI footcontroller sends a program change message on the selected MIDI channel, which selects a given preset. To figure out what MIDI channel the Axe-FX is listening to, go into the MIDI tab in the I/O menu.
  3. Once you have the pedal board sending program change messages and controlling the Axe-FX, that's when the real fun starts. Many pedal boards can be set up to send "IA" (or Instant Access) messages. This essentially involves sending a 0 (off) or 127 (on) value for a controller. There are two ways to use IA messages:
    • Pre-assign IAs to control specific effects. Whenever you have that given effect in a preset, sending that IA message will have the exact same result. You can do this from the Ctrl tab in the I/O menu. Pressing [Enter] for a given item here will put the Axe-FX into learning mode. Then, just hit the button that sends the IA message on your controller, and you're done. To me, this is the less interesting way to use IAs
    • Assign preset-specific IAs to change behavior on one or more blocks in a preset. This is the most flexible way to control the Axe-FX from a MIDI pedal board. In order to do so, you need to assign "External" controllers to MIDI CC numbers. These could be IAs or these could come from a real continuous controller (e.g. expression pedal plugged into the pedalboard) - it doesn't matter. Once you've set an "External" controller to be tied to a given CC, you can use that controller as a modifier for any of the controllable parameters in your preset, and you can use the same external controller to do multiple things (e.g. raise the gain on an amp and lower the level, as someone talked about earlier). You use the same menu to set this up (I/O->Ctrl). Select the desired External 1-8, hit enter, wiggle the pedal, and you're set.
  4. If you want to control the wah/volume/drive or any other continuously variable parameter using MIDI, you need to use a device like an expression pedal. This expression pedal sends continuous integer values from 0(0%)-127 (10%) for a given CC to the Axe-FX. Once you've assigned the CC to an External Controller (the same way as you'd do to for an IA), you can then assign that External Controller to the parameter you want to vary continuously. For controlling the Wah, for example, you'd assign the controller to the "Frequency" parameter in the Wah block. The possibilities are virtually endless.


Some other helpful tips:

  1. Pressing [Enter] on any modifiable parameter brings up the modifier screen where you can select the external controller you want to use to control the parameter. The graph settings control what happens when you press the button. If you're using IA, the only two values that matter are 0% and 100%. If you're using an expression pedal, the entire graph matters because it defines how the controlled parameter changes.
  2. You can press [Enter] on the "bypass mode" to assign an external controller to bypass an effect.
  3. You can assign an external controller to do whatever you want, and you can have it behave differently for every effect/parameter you set it to control.