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MIDI Functions
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In the rear panel of your PSR-550, there are MIDI terminals (MIDI IN, MIDI OUT), a TO HOST terminal,
and a HOST SELECT switch. By using the MIDI functions you can expand your musical possibilities. This
section explains what MIDI is, and what it can do, as well as how you can use MIDI on your PSR-550.
● If you don’t know what MIDI is, make sure to read these sections:
• What’s MIDI?.............................................................................................. page 106
• What You Can Do With MIDI ......................................................................page 108
• MIDI Data Compatibility .............................................................................page 109
● If you want to use your PSR-550 with a computer, read this section:
• Connecting to a Personal Computer.......................................................... page 110
● The PSR-550 lets you make the following MIDI-related settings:
• MIDI Template............................................................................................ page 112
• MIDI Transmit Setting.................................................................................page 114
• MIDI Receive Setting .................................................................................page 115
• Local Control.............................................................................................. page 116
• Clock ..........................................................................................................page 116
• Initial Data Send......................................................................................... page 117
What’s 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 acous-
tic 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 playing a note?
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 information 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-550 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) 01 (grand piano)
Note number (with which key) 60 (C3)
Note on (when was it pressed) and Timing expressed numerically (quarter note)
note off (when was it released)
Velocity (about how strong) 120 (strong)
Sampling
Note Sampling
Note
Tone Generator
(Electric circuit)
Playing the keyboard
RL
● Acoustic guitar note production
Pluck a string and the body resonates
the sound.
● Digital instrument note production
Based on playing information from the keyboard, a
sampling note stored in the tone generator is played
through the speakers.