M-AUDIO 61 - Manual (Page 39)

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38 ProKeys Sono 61 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 programs + 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 synthesizer .
For example, devices that are built according
to Roland’s GS specification or Yamaha’s XG
specification require you to specify a bank
change in order to access the extra voices 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
you can often ignore the LSB message .
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