Purchase a generic MIDI trigger or MIDI output device. Audio equipment retailers such as Guitar Center, Musician's Friend and Sam Ash stock a variety of MIDI controller units. At its most basic capacity, your MIDI device must be able to output MIDI data to a computer or audio effects processor using a USB or MIDI cable.
Connect the MIDI output device to your computer or audio effects processor using the necessary USB or MIDI cable. If you plan on using your MIDI pedal in conjunction with a digital audio workstation, or DAW, open your preferred software package and access the "MIDI I/O" settings. If your MIDI device is properly connected, it should appear as a viable option within the listings for potential MIDI input devices. Select it within this menu. If you are using an external digital effects processor, access and activate the equivalent parameters. After adjusting these settings, your DAW or effects unit will assign the MIDI input device to a specific MIDI channel. If you have only connected one device, it will typically utilize channel one.
Create an audio effect such as distortion or reverberation within the DAW or effects processor. Within the parameter settings for that particular effect, select the MIDI channel corresponding to your device. If only one device is connected, it will typically be associated with channel one.
Assign the MIDI trigger, or switch, on the pedal to the on/off activation of the desired effect. Select this activation process from within the audio effect's list of programmable functions and routing the MIDI trigger to it within the menu of available MIDI switches. If your MIDI pedal only has one switch, button or pedal, there will only be one available MIDI switch within this menu.
Place the MIDI pedal on the ground, checking that the device remains securely connected to the computer or external effects processor you are using in conjunction with it. Test the device by connecting your external instrument or microphone using your preferred mixer or audio interface combination, beginning a performance and activating the MIDI trigger. The sound produced by your instrument or voice will now take on the characteristics of the audio effect before playing out through speakers or headphones.