What is midi – Yamaha PORTATONE PSR-OR700 User Manual

Page 174

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Using

Your Instrument with

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PSR-OR700 Owner’s Manual

174

What is MIDI?

What is MIDI?

Put simply, MIDI is a data transfer standard that allows
easy and comprehensive control among electronic/digi-
tal music instruments and other devices. To get a better
idea of what MIDI does, let’s first consider acoustic
instruments, such as a grand piano and a classical gui-
tar. With the piano, you strike a key, and a hammer
inside hits some strings and plays a note. With the gui-
tar, 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 sampled note (previously recorded note)
stored in the tone generator section (electronic circuit)
is played based on information received from the key-
board.

Now, let’s examine what happens when we playback a
recording. When you play back a music CD (for exam-
ple, a solo piano recording), you’re hearing the actual
sound (vibration in air) of the acoustic instrument. This
is called audio data, to distinguish it from MIDI data.

In the above example, the actual acoustic sounds of the
pianist’s performance are captured in the recording as
audio data, and this is recorded to CD. When you play
back that CD on your audio system, you can hear the
actual piano performance. The piano itself is not neces-
sary, since the recording contains the actual sounds of
the piano, and your speakers reproduce them.

n

In the case of digital instruments, the audio signals are sent
through output jacks (such as [AUX OUT]) on the instrument.

The “controller” and “tone generator” in the illustration
above are equivalent to the piano in our acoustic exam-
ple. Here, the player’s performance on the keyboard is
captured as MIDI song data (see illustration below). In
order to record the audio performance on an acoustic
piano, special recording equipment is needed. How-
ever, since the PSR-OR700 features a built-in sequencer
that lets you record performance data, this recording
equipment is unnecessary. Instead, your digital instru-
ment allows you to both record and play back the data.

However, we also need a sound source to produce the
audio, which eventually comes from your speakers. The
tone generator of the instrument fills this function. The
recorded performance is reproduced by the sequencer,
playing back the song data, using a tone generator
capable of accurately producing various instrument
sounds — including that of a piano. Looked at in
another way, the relation of the sequencer and the tone
generator is similar to that of the pianist and the piano
— one plays the other. Since digital instruments handle
playback data and the actual sounds independently, we
can hear our piano performance played by another
instrument, such as guitar or violin.

n

Even though it is a single musical instrument, the PSR-OR700 can
be thought of as containing several electronic components: a con-
troller, a tone generator, and a sequencer.

R

L

Acoustic guitar note
production

Digital instrument note pro-
duction

Pluck a string and the
body resonates the
sound.

Based on playing information
from the keyboard, a sampled
note stored in the tone generator
is played through the speakers.

Playing the key board

Internal amp

Internal amp

Tone generator
(Electric circuit)

Recording

Playback

Recording and playing back the performance of an
acoustic instrument (audio data)

Recording and play back the performance of a digital
instrument (MIDI data)

Controller (keyboard, etc.)

Recording

Playback

USB storage
device

USB storage
device

Tone Generator

Sequencer

Tone generator

Sequencer

Keyboard performance (MIDI data)

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