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17
KeyRig 25 User Guide
MIDI Messages In-Depth
Program & Bank Changes
When the MIDI standard was first established, it enabled the user to access only 128 different sounds using program change messages
(0-127). As MIDI devices grew to be more sophisticated and contain more sounds, bank change messages were included in an updated
MIDI specification to allow for more than 128 sounds to be accessed.
The language MIDI uses to communicate between
musical instruments only allows for program change
commands 0-127, for a total of 128 possible
programs (127 pr program “0” = 128
programs total). Because of inherent limitations
of the MIDI communication protocol, the number
of directly accessible programs (using program
change messages) cannot easily be expanded
beyond 128. Thus, a system of banks, with 128
sounds in each, has been created that enables
manufacturers to overcome the 128-sound MIDI
limit.
128 Banks with 128 sounds in each bank is the
basic principle used to expand the number of
accessible sounds. However, to avoid reaching the
new limit of the resulting 16,384 possible sounds
(128 banks x 128 programs) accessible using a
bank change combined with a program change,
another layer of banks was added. The result is a
system of 128 banks that can contain 128 sub-
banks in each of them, which, in turn, can contain
128 sounds (programs) within them.
Bank change messages are useful when calling
up sounds from a large library that may exist in a
particular sound module or software synth. For
example devices that are built with Roland’s GS
specification or Yamaha’s XG specification require
you to specify a bank change in order to access the
extra voices and effects that these devices provide.
MIDI CC 0 is the bank select MSB (Most Significant
Byte) message. This MIDI message is 7-bit in size
and can be used to select any of 128 banks. This
message can be used in conjunction with MIDI CC
32 which is bank select LSB (Least Significant
Byte): a separate 7-bit message allowing additional
selection of any of another 128 sub-banks. The
combination of Bank MSB and LSB messages
gives a 14-bit message that can select any of a
possible 16,384 banks. Each bank can in turn
contain 128 possible sounds selected via a separate
program change MIDI message. This enables a user to theoretically recall over two million programs directly, using only MIDI commands.
However, most devices only use a few different banks, and allow you to access them with either a Bank LSB message or a Bank MSB
message. Please consult your synthesizer’s or software’s documentation for more information on which type of bank change messages
they can process.”
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