Midi Functions; What Is Midi - Yamaha PortaTone PSR-450 Owner's Manual

MIDI Functions

The PSR-450 is MIDI-compatible, featuring MIDI IN and MIDI OUT terminals and providing
a variety of MIDI-related controls. By using the MIDI functions you can expand your musi-
cal possibilities. This section explains what MIDI is, and what it can do, as well as how
you can use MIDI on your PSR-450.

What Is MIDI?

No doubt you have heard the terms "acoustic instrument" and "digital instrument." In the world
today, these are the two main categories of instruments. Let's consider an acoustic piano and a
classical guitar as representative acoustic instruments. They are easy to understand. With the
piano, you strike a key, and a hammer inside hits some strings and plays a note. With the guitar,
you directly pluck a string and the note sounds. But how does a digital instrument go about play-
ing a note?
● Acoustic guitar note production
Pluck a string and the body reso-
nates the sound.
As shown in the illustration above, in an electronic instrument the sampling note (previously
recorded note) stored in the tone generator section (electronic circuit) is played based on infor-
mation received from the keyboard. So then what is the information from the keyboard that
becomes the basis for note production?
For example, let's say you play a "C" quarter note using the grand piano sound on the PSR-450
keyboard. Unlike an acoustic instrument that puts out a resonated note, the electronic instrument
puts out information from the keyboard such as "with what voice," "with which key," "about
how strong," "when was it pressed," and "when was it released." Then each piece of information
is changed into a number value and sent to the tone generator. Using these numbers as a basis,
the tone generator plays the stored sampling note.
[ Example of Keyboard Information ]
Voice number (with what voice)
Note number (with which key)
Note on (when was it pressed) and
note off (when was it released)
Velocity (about how strong)
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PSR-450 Owner's Manual
● Digital instrument note production
Tone Generator
L
Sampling (Electronic circuit)
Note
Playing the keyboard
Based on playing information from the keyboard,
a sampling note stored in the tone generator is
played through the speakers.
001 (Grand Piano)
60 (C3)
Timing expressed numerically (quarter note)
120 (strong)
R
Sampling
Note