Midi Functions; What's Midi - Yamaha DD-55 Owner's Manual

MIDI Functions

The MIDI IN and MIDI OUT terminals, located on the DD-55's right side panel, offer
broadened musical possibilities through use of MIDI. What is MIDI? What can you do
with MIDI? And how can you use MIDI with the DD-55? Here are some answers to
those questions...
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. 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?
● 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 information
received from the pads and pedals. So then what is the information from the pads and pedals 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 keyboard.
Unlike an acoustic instrument that puts out a resonated note, the electronic instrument puts out infor-
mation 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)

What's MIDI?

● Digital instrument note production
Sampling
Tone Generator
Note
Playing the
pads
Based on playing information from the pads and
pedals, a sampling note stored in the tone genera-
tor is played through the speakers.
01 (grand piano)
60 (C3)
Timing expressed numerically
(quarter note)
120 (strong)
(Electronic
circuit)
Sampling
Note
21