For this example, we'll map the Expression Pedal of our KB37 to the Wah - Position parameter of the GearBox or POD Farm 1 or 2 Audio Units Plug-Ins. The steps are very similar for configuring MIDI control of a parameter in practically any Logic or Audio Units effects Plug-In as well.
• Create an Audio track in your Logic session, and record or insert an audio file so you'll have something to hear your Plug-In effect applied to. A nice clean guitar recording wold work nicely here.
• Click on an Effects Insert slot for this Logic Audio track and insert the GearBox or POD Farm Plug-In.
• In the Plug-In window, load a Tone preset, and click on the Wah pedal effect to make sure it is "on" and to show the Wah effect's edit settings in the edit panel (or, in POD Farm 1 Plug-In, bring up the Wah Edit Panel).
• For POD Farm 2 Plug-In - You need to first assign the Wah - Position knob parameter to one
of the POD Farm 2 Plug-In Automation Slots. Ctrl+click directly on the Wah Position knob and then click on an empty Slot to assign it, as we've done
here for Slot 1:
• Next, (before you click on anything else) go to the Logic > Preferences > Control Surfaces menu, and you want to select Learn Assignment for "Wah - Position" (or, for POD Farm 2 Plug-In, choose Learn Assignment for "Parameter 1").
• As you can see by the name of the "Learn Assignment..." menu command, Logic automatically detected the plug-in "Wah - Position" parameter since it was the last item you selected with your mouse in the previous step.
• When you select this "Learn Assignment..." menu command, it launches the Logic Controller Assignments dialog, and a message informs you that it is waiting for you to access your MIDI Controller so that it can "Learn" the MIDI command from it.
• Now move your Expression Pedal, and you should see the Controller Assignment dialog receive and "Learn" the MIDI Control message (which is configured to transmit MIDI CC 11, with a Value range of 0 - 127, as part of the MIDI Default preset we previously selected in the Line 6 Audio-MIDI Settings).
• Exit the Controller Assignments dialog and give the Expression Pedal a try. You should see the Position knob within the GearBox/POD Farm Plug-In window move in response. Press Play in Logic to hear your audio track play, and when you move the pedal, you should hear the Wah effect do its thing on your track!
• Note that you can also set your Logic Audio track to record automation for this Plug-In, Wah Position parameter, and you can use the pedal to record a Wah "performance" too. You should be able to repeat the above steps to access any mappable parameter in Logic with any of your KB37/UX2/UX8 MIDI Controllers - Mixer faders, Pan knobs, solo switch, Software Instrument knobs, other Plug-In parameters, etc. So free up your hands and start playing!