Roland Sound Canvas Digital SC-D70 Owner's Manual page 47

MIDI channels and multitimbral sound generators
MIDI can send numerous streams of performance data over a single MIDI cable. This
is made possible by MIDI channels. From the large amount of data that it receives,
the receiving device can select and use only the data that is intended for it.
MIDI channels are analogous to the channels on a television. By changing channels
on a television you can view programs from many different broadcast stations. You
can select the program you wish to view by setting the television to match the
channel of the desired broadcast station. In MIDI as well, messages are received
when the receive channel matches the transmit channel.
fig.25-02.e
Station A
Station B
Station C
The cable from the antenna carries the TV signals from many broadcast stations.
There are sixteen MIDI channels, numbered 1–16. Music data is received when the
transmit channel of the transmitting device matches the receive channel of the
receiving device.
If you set MIDI channels as shown below, playing the keyboard will cause only
sound generator B to produce sound; sound generator A will not produce sound.
This is because sound generator B is set to the channel the keyboard is transmitting
on, while sound generator A does not use a matching channel (figure 1). On the other
hand, if you set the transmit channel of the keyboard to match sound generator A,
sound generator A will produce sound (figure 2).
fig.25-03.e
MIDI OUT
Transmit Channel: 1
Fig. 1
MIDI Keyboard
MIDI OUT
Transmit Channel: 2
Fig. 2
MIDI Keyboard
Since the SC-D70 has one MIDI IN, it is able to receive 16 channels of messages. By
using 16 channels you can play a sixteen-part ensemble. (If you wish to use 32 parts
you must use a USB cable.) A sound generator like the SC-D70 that is able to play
many parts simultaneously is called a multitimbral sound generator. The term
"timbre" means "sound" or "tone."
There are two kinds of parts: normal parts and drum parts (p. 31). Normal parts are
used to play melody or bass. On a GM/GS sound generator, channel 10 is the drum
part channel.
MIDI IN MIDI THRU
Receive
Channel: 2
Sound
Module A
Receive
Channel: 1
MIDI IN
Sound
Module B
MIDI IN MIDI THRU
Receive
Channel: 2
Sound
Module A
Receive
Channel: 1
MIDI IN
Sound
Module B
The TV is set to the channel
of the station you wish to watch.
Appendix
47