General MIDI Level 2 is a specification tat was released by the MIDI Manufacturer's Association in 1999. It is based on the earlier General MIDI specification, but includes many enhancements.
GM Level 2 mandates that all compatible devices support:
Level 2 builds on GM by adding another 128 instruments to the core set. These sounds are in "variation banks" with the same patch number as GM1. For instance, patch #1, "Acoustic Grand Piano" has the bank 1 variation "Wide Acoustic rand" and bank 2 variation "Dark Acoustic Grand".
The number of variation banks vary by instrument and some instruments such as the Celesta and Glockenspiel don't have variation banks specified.
Some instrument names have changed. For the most part they are the same instruments, but some have changed names enough that they might result in different sounds than a level 1 sound set:#5: Electric Piano 1 is now Rhodes Piano
Drum sounds are based on Roland GS.
These kits are:#1 Standard Kit (same as General MIDI 1)
These added drum notes are based on Roland GS.
#27 High Q
#29 Scratch Push
#30 Scratch Pull
#32 Square Click
#33 Metronome Click
#34 Metronome Bell
#83 Jingle Bell
#86 Mute Surdo
#87 Open Surdo
GM2 adds a few control change messages:#71 Filter Resonance
In addition to the added control changes, sysex messages have been added to control the parameters for reverb and chorus effects. It also added key-based instrument controllers so that the different drums in a drum map can have different pan, chorus, reverb, or volume settings.