Alesis SR-16 User Manual - Page 67
About Sequencing, MIDI CHANNEL MESSAGES, Voice Messages, Note On, Note Off, Velocity
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16's MIDI out jack can be switched to a thru function that merges MIDI in data with SR-16 MIDI data. 9.1B About Sequencing Sequencing, the computerized equivalent of tape recording, is a very common and popular MIDI application. The SR-16 is a special-purpose sequencer optimized for drum machine applications. Sequencing takes advantage of the fact that MIDI data can be time-stamped with rhythmic data and recorded in computer memory. The computer acts like a recorder, but instead of recording audio, it stores digital data that represents the pads you played, the exact order in which you played those pads, and the pad dynamics. Once stored in memory, the performance can be played back. The principle is the same as a player piano, but instead of having keys triggered by holes in a roll of paper, drum sounds are triggered by data contained in the computer's memory. The SR-16 also works well as a drum sound expander module for separate stand-alone or computer-based sequencers. Each of MIDI's 16 available channels can carry a unique set of MIDI data. Since all this data travels over one cable, each piece of data includes its appropriate channel ID so that MIDI receivers can "tune in" to a particular channel and accept only that data. The SR-16 can tune in to the channel that plays drum notes, and respond by triggering sounds. 9.2 MIDI CHANNEL MESSAGES There are two main types of MIDI messages. Channel messages, which are channel-specific, consist of Voice and Mode messages. System messages, which do not have a channel number and are received by all units in a system, include Common, Real Time, and Exclusive messages. 9.2A Voice Messages Playing a pad on the SR-16 produces the following MIDI data: Note On Corresponds to the pad's assigned MIDI pitch; values can range from 000 (lowest note) to 127 (highest note). Middle C is 60. Note Off This indicates the end of the note. Velocity Corresponds to the dynamics of your playing; values range from 001 (minimum velocity) to 127 (maximum velocity). 63