What is MIDI ?
Simple MIDI
Turn on your Lightmaster XLS, plug in a MIDI
cable from a keyboard to the MIDI ‘IN’ socket,
ensure that the Mode switch is set to Presets.
Any note played on the keyboard will turn a
channel on. Yes it’s that easy!
If this doesn’t work, someone has been
experimenting with MIDI on the desk, go into
Super User and perform a desk Reset. See Page
20.
To use MIDI to link desks for Master / Slave
operation or for transferring desk memories, see
page 22.
The introduction to MIDI below will help if you
need or want to know the technical details.
Introduction to MIDI
MIDI (Musical Instrument Digital Interface) was
originally designed as a means of communication
between electronic musical instruments. Some of
the concepts involved are important to
understand before starting to program the desk to
respond in a particular way to MIDI commands.
Communication
MIDI is a means of communication between
musical instruments. Most MIDI devices have
three MIDI connectors known as ‘ports’ - ‘IN’,
‘THRU’, and ‘OUT’; Some have ‘IN’ and ‘OUT’
only. Data is only sent out from the out port and
only received on the in port.
Transmit and Receive Channels
MIDI has separate Transmit and Receive
channels each numbered 1 to 16.
By setting receive to a particular channel, only the
signals that are wanted will be received.
Alternatively, Receive may be set to respond to
all channels so that any MIDI information
transmitted will be received, this may be good or
bad .
The Transmit channel must be set to a specific
channel (1 to 16).
For two MIDI instruments to communicate with
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each other in a system with many other
instruments connected, they must be set up to
use Transmit and Receive channels that are not
used by other instruments.
Note Numbers
The MIDI standard assigns ‘Note Numbers’ to
musical notes. Middle C is number 60. C on the
octave below is 48 and so on.
Associated ‘note
on’ data is sent when a key is pressed, the action
caused by the ‘note on’ will continue until ‘note
off’ data is received when the key is released.
Voices (Program Changes)
Most MIDI musical instruments have ‘voices’ such
as Piano, Harpsichord and so on. Changing these
clearly changes the type of sound that is played.
When a voice is changed, a signal called a
Program Change is sent on the Transmit channel
assigned to the instrument. Any device which has
been set up to receive data on this channel will
respond to the Program Change. Program
Changes values can not be greater than 127.
Bank Select.
Is very much like Program Change except that it
is used to access numbers greater that 127,
which is the limit for Program Change.
Velocity Sensing
Some keyboards have this function. It enables the
musician to control the loudness of the music by
playing notes and chords delicately for soft music
or hard for loud music. The MIDI signal that is
transmitted by such instruments includes a
Velocity in the range 1 to 127.
If the instrument does not have Velocity sensing,
the Velocity is fixed by the manufacturer, often at
63 rather than 127 so that the music that is being
played is not too loud.
Summary
MIDI instruments send a stream of signals from
their ‘OUT’ port. The signals sent principally
consist of Note On messages, to turn Note on,
and Note offs, to turn a note off. A Note on
consists of a Note On command followed by a
variable number of pairs of Note Numbers and
Velocities.
There may be the occasional Program Change
signal if the voice is changed.
MIDI Transmitted
MIDI is transmitted continuously except in
Program and MIDI Setup In / Slave modes.
MIDI and the Lightmaster XLS
The Lightmaster XLS is designed principally to
receive MIDI information, mainly note on, note off
and program Changes. It only transmits
information that is of use to another XLS or a
computer.
The Lightmaster XLS uses note numbers to
select Faders / Auxiliary Memories to be turned
on and off.
Velocity Sensing is used to set the level of the
faders.
Only a group of 24 channels / memories can be
accessed at one time, but the start of the group
can be moved from page 0, channel 1 to any
page any channel. Selection of the 1st in a group
is achieved by use of the Program Change
command.
Some of the ways the Lightmaster XLS uses MIDI
to achieve clever effects such as foot switch and
desk linking may not be compatible with other
MIDI equipment.
What is MIDI ?
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