The first thing you need to know about is MIDI. MIDI is the Musical Instrument Data Interface - a common control signal between musical instruments, effects, sequencers, samplers, etc... |
There are several different types of MIDI signals that certain units can and cannot send or receive. The four main ones we're concerned with here are: Program Change Messages, Note Trigger Messages, Control Change Messages, and SYSEX Messages.
MIDI Program Change Messages
Program Change Messages are used to switch banks and patches on intstruments and effects. Program Change Messages transmit two pieces of data (MIDI Channel [1-16] and Bank/Patch Number [0-127]) All of the listed MIDI control pedals have the capability to send Program Change Messages. This will allow you to switch patches on the fly, with the press of your foot.
MIDI Note Trigger Messages
Note Trigger Messages are used to play notes or samples from sound units, or to change the key, scale or tonal quality of effects settings. Basic Note Trigger Messages transmit three pieces of data (MIDI Channel [1-16], Note Number [0-127], and Velocity [0-127]) - some units can send or receive additional pieces of data such as Note Aftertouch and Sustain. All of the listed MIDI controllers can send Basic Note Trigger Messages, however, the Roland PK-5 and PK-7 go far beyond Basic Note Triggering. They offer 1-octave and 2-octaves respectively of piano-style foot pedals. With the PK series, you can trigger synthesizer basslines with your feet, ranging a full chromatic scale of notes. When used with vocal You can change the tonal quality or scale degree of effects on the fly. For example, say you are using a Vocoder Vocal Effect - with the PK series pedals, you can switch the synthesis source to the vocoder as you sing, and perhaps simultanaeously trigger an arpegiated bass line.
MIDI Control Change Messages
Control Change Messages are used to switch on and off effects, to change levels of effects, and change the levels of several basic functions (volume, pan, pitch) Control Change Messages transmit three pieces of data (MIDI Channel [1-16], Controller Number [0-127] and Control Value [0-127]) Control Change Messages can be a single message sent with a specific value, or can continuously transmit a message with changing values. Continuous change messages are typical for expression pedals, faders, and rotary dials... they send ultra fast, continuous messages to gently alter the effect level up or down.