W. J. Melvin
W. J. Melvin Musician, producer, sound engineer, music director, composer, director of MIDI technology @beat_bars

How to control MainStage 3 with a foot controller

How to control MainStage 3 with a foot controller

After a brief introduction on controlling Amp Sims using foot controllers, let’s move on to the details. In this blog post, I will describe how to control Apple MainStage 3.

I will start with a very simple example to demonstrate the standard approach, and then show you how to use the minimum amount of equipment (only 2 buttons and one pedal) to set and control any number of effects in MainStage 3.

Approach 1

Suppose you only have the overdrive and wah‑wah effect on your pedalboard. You want to turn each one on and off using the footswitch and control the wah‑wah effect with the pedal.

As for hardware, you need one regular expression pedal, one double footswitch, and one USB MIDI adapter.

Once you have your MIDI foot controllers ready, open your MainStage Concert in “Edit” mode.
MainStage Edit View

Now add a New Assignment:
New Assignment

Make sure you have the “Selection follows incoming MIDI” option selected.

Click on the newly created Assignment to make the “Assign & Map” button enabled. Click on this button to activate “MIDI Learn” mode (the button turns red):
Assign and Map - MIDI Learn

Press the button on the footswitch - this way you will assign a MIDI event to this Assignment.
Click the red “Assign & Map” button again to deactivate “MIDI Learn” mode.
Assign and Map - Unmapped

You are done with the “Assign” operation, now let’s move on to the “Map” procedure.

In the “Control Inspector” view below the “Assignments & Mappings” view, under the “Unmapped” tab, there is a list of possible parameters to be mapped:
Control Inspector
Click: Your strip name ► Pedalboard ► Wah‑Wah Slot ► Pedal Position

The new Assignment is now fully configured:
Assign and Map - Mapped

From this moment, each time you depress your pedal, you will hear the wah‑wah effect.

Proceed in the same way by assigning and mapping both footswitch buttons to toggle the wah‑wah and overdrive effects on and off.

Approach 2

Add the whammy pedal to the Approach 1 configuration. We also want to turn it on and off and control it using the pedal. In the standard approach described above, we would have to buy a second expression pedal, a second footswitch, and an additional MIDI adapter.

To avoid this and use only the equipment we have, we can apply one simple trick - switch between entire Programs.
A Program, i.e. a Patch, is a whole group of effects and their settings.

After adding the whammy effect to the Patch, duplicate it.
Patch Duplicate

Then, in the Patch Settings, change the Program Change number that will activate this Patch:
Program Change
(I described the “Program Change” message in more detail here)

Proceed in the same way as in Approach 1, assigning the expression pedal to different effects in each Patch - wah‑wah or whammy, while setting one of them on and the other off:

Patch       wah‑wah       whammy      
1 on off
2 off on


In addition, you can duplicate these Programs again, and in each Program set whether overdrive is enabled or not:

Patch       wah‑wah       whammy       overdrive      
1 on off on
2 off on on
3 on off off
4 off on off


(Don’t forget to set the subsequent “Program Change” number for each Patch)

Having these four programs defined, we can move between them up and down, thanks to the function available in the MIDI controller:
beat bars config

This way, having only two buttons physically available, we can use any number of configurations switching between the entire groups, not just turning individual effects on and off.

In the next blog posts, I will describe how to configure other Amp Sims.
Stay tuned.

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