If you have been around a keyboard or digital piano within the past few years, you probably have heard references to General MIDI and General MIDI 2. How does that fit in with MIDI? Is there a difference, and should you care? The answer depends on if you plan to share your MIDI work with other musicians or if you will be saving the data just for your own use. If it is the latter, then you really can save the file in any format you want since you will be the only person using the file.
If you would like to take a MIDI file of one of your performances and share it with others, then you will want to follow the basic rules of General MIDI, usually referred to as GM or GM2, which is short for General MIDI 2.
Just about any keyboard, digital piano, or organ made over the past couple of years will be GM aware, and more than likely will be GM2 capable. To verify that your keyboard supports GM or GM2 first, look in your owner’s manual. You should also be able to find the GM or GM2 logos on your keyboard.
Both GM and GM2 formats are nothing more than a standard that allows any piece of equipment displaying the GM or GM2 logo to understand and share data in those formats. That means if you record a song and you select an Acoustic Bass, Piano, and Standard Drum Set, you can expect the file to playback on any GM/GM2 instrument with the same instruments – Acoustic Bass, Piano, and Standard Drum Set. While those instruments’ sound quality may vary from vendor to vendor, you can expect them to be reasonably close.
General MIDI, created back in the 1980s, is still in use today. There are 128 instruments in the General MIDI patch map. The instruments are grouped into various instrument families.
General MIDI Level 1 Instrument Families
|Program Number||Family Name||Program Number||Family Name|
General MIDI Level 1 Instrument Patch Map
|Program Number||Instrument Name||Program Number||Instrument Name|
|1||Acoustic Grand Piano||65||Soprano Sax|
|2||Bright Acoustic Piano||66||Alto Sax|
|3||Electric Grand Piano||67||Tenor Sax|
|4||Honky-tonk Piano||68||Baritone Sax|
|5||Electric Piano 1||69||Oboe|
|6||Electric Piano 2||70||English Horn|
|17||Drawbar Organ||81||Lead 1 (square)|
|18||Percussive Organ||82||Lead 2 (sawtooth)|
|19||Rock Organ||83||Lead 3 (calliope)|
|20||Church Organ||84||Lead 4 (chiff)|
|21||Reed Organ||85||Lead 5 (charang)|
|22||Accordion||86||Lead 6 (voice)|
|23||Harmonica||87||Lead 7 (fifths)|
|24||Tango Accordion||88||Lead 8 (bass + lead)|
|25||Acoustic Guitar (nylon)||89||Pad 1 (new age)|
|26||Acoustic Guitar (steel)||90||Pad 2 (warm)|
|27||Electric Guitar (jazz)||91||Pad 3 (polysynth)|
|28||Electric Guitar (clean)||92||Pad 4 (choir)|
|29||Electric Guitar (muted)||93||Pad 5 (bowed)|
|30||Overdriven Guitar||94||Pad 6 (metallic)|
|31||Distortion Guitar||95||Pad 7 (halo)|
|32||Guitar harmonics||96||Pad 8 (sweep)|
|33||Acoustic Bass||97||FX 1 (rain)|
|34||Electric Bass (finger)||98||FX 2 (soundtrack)|
|35||Electric Bass (pick)||99||FX 3 (crystal)|
|36||Fretless Bass||100||FX 4 (atmosphere)|
|37||Slap Bass 1||101||FX 5 (brightness)|
|38||Slap Bass 2||102||FX 6 (goblins)|
|39||Synth Bass 1||103||FX 7 (echoes)|
|40||Synth Bass 2||104||FX 8 (sci-fi)|
|46||Pizzicato Strings||110||Bag pipe|
|49||String Ensemble 1||113||Tinkle Bell|
|50||String Ensemble 2||114||Agogo|
|51||SynthStrings 1||115||Steel Drums|
|53||Choir Aahs||117||Taiko Drum|
|54||Voice Oohs||118||Melodic Tom|
|55||Synth Voice||119||Synth Drum|
|56||Orchestra Hit||120||Reverse Cymbal|
|57||Trumpet||121||Guitar Fret Noise|
|60||Muted Trumpet||124||Bird Tweet|
|61||French Horn||125||Telephone Ring|
In the percussion sounds, each will be located at the same note location. For example, note number 35 would be the bass drum. When you play note 35 on MIDI channel 10, and you are in GM mode, you will always hear a bass drum.
General MIDI Level 1 Percussion Key Map
|Note Number||Percussion Sound||Note Number||Percussion Sound|
|35||Acoustic Bass Drum||59||Ride Cymbal 2|
|36||Bass Drum 1||60||Hi Bongo|
|37||Side Stick||61||Low Bongo|
|38||Acoustic Snare||62||Mute Hi Conga|
|39||Hand Clap||63||Open Hi Conga|
|40||Electric Snare||64||Low Conga|
|41||Low Floor Tom||65||High Timbale|
|42||Closed Hi Hat||66||Low Timbale|
|43||High Floor Tom||67||High Agogo|
|44||Pedal Hi-Hat||68||Low Agogo|
|47||Low-Mid Tom||71||Short Whistle|
|48||Hi-Mid Tom||72||Long Whistle|
|49||Crash Cymbal 1||73||Short Guiro|
|50||High Tom||74||Long Guiro|
|51||Ride Cymbal 1||75||Claves|
|52||Chinese Cymbal||76||Hi Wood Block|
|53||Ride Bell||77||Low Wood Block|
|55||Splash Cymbal||79||Open Cuica|
|57||Crash Cymbal 2||81||Open Triangle|
Although you have access to 128 instruments in General MIDI mode, you will only have access to one drum kit, the standard drum kit.
This is a perfect lead-in for GM2 or General MIDI 2. Introduced in 1999 as an extension to the original GM format, GM2 allows both MIDI channels 10 and 11 for percussion parts along with the essential MIDI bank change command.
Let’s go back to the Bass Drum example. In General MIDI, we mentioned that you could only access the standard drum kit. You probably have multiple drum kits on your instrument. Depending on the type of music you are performing, selecting the correct drum kit can make or break the performance. To access a different drum kit, you need to issue a bank change command and the program number of the desired drum kit. In GM2 mode, nine drum kits are available.
GM2 Drum Kits
The same thing is true for your instrument patches. You will be able to select additional banks of instruments by using the bank select command. In GM2, the number of instruments you will have access to grows to 256 instruments compared to only 128 in GM mode. The additional instruments fall under the same instrument families found in GM. For example, in the piano family, you will find Detuned Electric Piano located in Bank 1 Program Number 5 and Detuned Electric Piano2 located in Bank 1 Program Number 6. This is in addition to the Electric Piano 1 and Electric Piano 2 piano offered in GM mode, located in Bank 0 in the same program number locations (5 and 6).
To summarize, GM2 files will offer a wider palette of sounds and supporting effects, along with additional control features allowing more editing of the final musical performance.
So what does all this sound like? Take a listen to a short sample of a jazz arrangement of Bach Prelude XV, which is a General MIDI format sequence using the instruments mentioned earlier, Acoustic Bass, Piano, and Standard Drum Set.
Since this file is saved in General MIDI format, it will play the correct instruments regardless of the manufacturer of the GM capable MIDI device it is played back on. That could be the sound card in your computer or your multi-thousand dollar keyboard. The only difference in the final listening experience will be the quality of the sampled instruments your MIDI device offers.
Cited from https://immusic.co/gm_gm2_overview/