Yamaha CP60M Technical Information download pdf (Page 13)

MIDI

Understand

..

ingThe

Four

Basic MIDI

Modes.

By

Tom

Darter.

Here

is

a

basic

setup

using MIDI

Mode

3

with

the

TX8r6.

Each

module

of

the

TX8r6

should

be

sec

(in

Mode

3)

so

that

its MIDI

channel

matches

the

MIDI

channel

of

the

QXI

MIDI

OUT

rerminal

to

which

it

is

a>rmectaL

AS

INFORMATION

travels

down

a

MIDI

.n.

cable,

it

may

be

sent

to

(or

through)

a

number

of

instruments;

but

each

instrument

may

respond

to

this

information

differently,

depending

on

how

it

has

been

set

to

operate. In

other

words,

MIDI

instruments have a

number

of

different

modes

of

operation,

and

these

modes

determine

how

the

instrument

will react

to

MIDI

information.

Along

with

MIDI

chan-

nels

[explained

in

last

month's

MIDI

article],

the

MIDI modes are the

most

important

ele-

ments

that

contribute

to

MIDI's ability

to

per-

form

musical sleight-of-hand.

Most

basic

MIDI

information

(such

as a

"note-on"

or

"note-off'')

comes complete with

an

informational "flag"

that

assigns

it

to

one

of

the

16

MIDI

channels.

For

instruments receiv-

ing this information,

there

are

two

possibil-

ities-either

the

instrument

will

be

assigned

to

recognize

and

respond

to

information

on

one

specific

MIDI

channel,

or

it

will

be

assigned

to

respond

to

all

MIDI

information, regardless

of

channel.

This

second

condition

is

called

"OMNI."

When

an

instrument is not set

up

in

OMNI,

it

responds

only

to

information

on

the

MIDI

channel

to

which

it

is assigned.

In

addition,

it

may

respond

to

this

channel

information

in

different ways, depending

on

whether

it

is set

up

to

act

like

a

POLYphonic

instrument

or

a

MONOphonic

instrument.

All

in

all, there are

four

MIDI

Modes-four

different ways

that

an

instrument

may

respond

to

incoming

MIDI

information.

These

four

modes

are specified

by

different

combinations

of

the

three

MIDI

mode

messages

outlined

above:

OMNI,

POLY,

and

MONO.

The

com-

binations

are

pretty

obvious,

based

on

two

simple

conditions:

An

instrument

can

be

in

OMNI

or

not,

and

it

may

be

either POLY-

phonic

or

MONOphonic.

With

these condi-

tions

in

mind,

the

four

MIDI

modes

are easy

to

understand. Here they are:

Mode

1:

OMNI

ON,

POLY.

An

instrument

in

Mode

1

will

respond

to

MIDI

information

sent

over

any

of

the

16

MIDI

channels.

This

mode

is sometimes called

OMNI

mode.

Mode

2:

OMNI

ON,

MONO.

This

mode

assigns

MIDI

information

sent

over

any

of

the

16 MIDI channels

to

one

voice.

When

set in this

mode,

an

instrument

will always play

mono-

phonically

(one

note

at

a time},

no

matter

how

much

information is being

sent

over

the

various

MIDI

channels.

Mode

3:

OMNI

OFF, POLY.

In

this mode,

an

instrument

will

only

respond

to

the

MIDI

information being sent

on

the

channel

to

which

it

is

assigned.

Mode

3 is

also

known

as

POLY

mode.

Mode

4:

OMNI

OFF,

MONO.

In

this

mode,

an

instrument

will only

respond

to

MIDI

information being sent

on

the

channel

to

which

it is assigned,

and

it

will

respond

to

that infor-

mation

monophonically.

Mode

4,

also

known

as

MONO

mode,

is

most

often used in multi-

timbral

instruments,

where

each

voice

can

be

assigned

to

a separate

MIDI

channel.

Since

most

synthesizers

today

are

poly-

phonic,

Mode

2

(OMNI

ON,

MONO)

is

the

least

common

of

the

four.

Mode

3 ( 0

MNI

OFF,

POLY)isthemostcommon,

especially

when

a

number

of

instruments

are

being

used

with

a

sequencer.

The

basic

operation

of

the

TX816

with

the

QX

1,

for

example,

will

most

often involve

Mode

3.

In

the

early days

of

MIDI, many instruments

were

programmed

so

that

they

were

in

OMNI

mode

when

turned

on.

This

basic

"default"

setting

is

still

quite

common,

though

not

as

much

as

it

was

at

the

beginning

of

MIDI.

The

DX7,

for

instance,

functions

in

POLY

mode

(MODE

3

},

and,

when

turned

on,

is

initially

assigned

to

MIDI

channell.

As

mentioned

above,

Mode

4

(ONMI

OFF,

MONO)

is usually reserved for use with multi-

timbral

instruments

such

as

the

Oberheirn

X

pander.

Each

of

the

X

pander's

six

voices

operate like a complete

monophonic

synthe-

sizer. By assigning each voice

to

a different MIDI

channel,

it

is

possible

create

multi-timbral

polyphony

by

controlling

the

X

pander

with

a

multi-channel

MIDI

sequencer.

So,

there

is

the

story

of

the

four

MIDI

Modes.

They

determine

how

any

given

MIDI

instrument

will

respond

to

information sent

on

the

16MIDichannels.

Vol. 1

No.3/

AFfERTOUCH

13

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