ALESIS SR-16 - Manual (Page 67)

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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).