What Is General MIDI Level 1 Sound Set Arrangement?

The General MIDI Level 1 (GM1) sound set bank arrangement is a standardized specification established in 1991 by the MIDI Manufacturers Association (MMA) to ensure that MIDI compositions sound consistent across different hardware synthesizers, sound cards, and playback devices. Before this standard, sending a MIDI program change for an acoustic piano to a different brand of synthesizer could mistakenly trigger a flute or a synthesizer lead. GM1 resolved this interoperability problem by establishing a fixed list of 128 melodic instrument sounds organized into 16 distinct instrument families, alongside a designated drum kit layout mapped to MIDI Channel 10.

Melodic Instrument Families

The GM1 melodic sound set encompasses 128 instrument patches (numbered 1 through 128 in user-facing numbering, or 0 through 127 in zero-indexed digital representations). These patches are grouped into 16 functional families containing eight instruments each:

  1. Piano (Patches 1–8): Acoustic grand, bright, electric, and honky-tonk pianos, plus harpsichord and clavinet.
  2. Chromatic Percussion (Patches 9–16): Celesta, glockenspiel, music box, vibraphone, marimba, xylophone, tubular bells, and dulcimer.
  3. Organ (Patches 17–24): Drawbar, percussive, rock, church, and reed organs, as well as accordion and harmonica.
  4. Guitar (Patches 25–32): Nylon, steel, jazz electric, clean electric, muted, overdriven, distorted, and guitar harmonics.
  5. Bass (Patches 33–40): Acoustic, finger, pick, fretless, slap, and synthesizer basses.
  6. Strings (Patches 41–48): Solo violin, viola, cello, and contrabass, plus tremolo, pizzicato, orchestral harp, and timpani.
  7. Ensemble (Patches 49–56): String ensembles, synth strings, and various vocal choir patches.
  8. Brass (Patches 57–64): Trumpet, trombone, tuba, muted trumpet, French horn, brass section, and synth brass variants.
  9. Reed (Patches 65–72): Soprano, alto, tenor, and baritone saxophones, alongside oboe, English horn, bassoon, and clarinet.
  10. Pipe (Patches 73–80): Piccolo, flute, recorder, pan flute, blown bottle, shakuhachi, whistle, and ocarina.
  11. Synth Lead (Patches 81–88): Common synthesizer lead waveforms, including square, sawtooth, calliope, chiff, charang, voice, fifths, and bass-plus-lead.
  12. Synth Pad (Patches 89–96): Ambient synthesizer textures including new age, warm, polysynth, choir, bowed, metallic, halo, and sweep pads.
  13. Synth Effects (Patches 97–104): Rain, soundtrack, crystal, atmosphere, brightness, goblins, echoes, and sci-fi sound effects.
  14. Ethnic (Patches 105–112): Traditional world instruments including sitar, banjo, shamisen, koto, kalimba, bagpipe, fiddle, and shanai.
  15. Percussive (Patches 113–120): Tinkle bell, agogo, steel drums, woodblock, taiko drum, melodic tom, synth drum, and reverse cymbal.
  16. Sound Effects (Patches 121–128): Real-world acoustic effects including guitar fret noise, breath noise, seashore, bird tweet, telephone ring, helicopter, applause, and gunshot.

The GM1 Percussion Map (Channel 10)

In addition to the melodic instrument arrangement, the GM1 standard reserves MIDI Channel 10 exclusively for non-pitched percussion. Unlike the melodic channels, where incoming note numbers determine the pitch of the selected patch, note numbers on Channel 10 trigger specific drum and percussion sounds.

The percussion map defines 47 standard drum sounds spanning from note number 35 (Acoustic Bass Drum) through note number 81 (Open Triangle). Standardized placements within this range include:

The standard also dictates exclusive groups (choke groups), ensuring that triggering a closed hi-hat (Note 42) automatically cuts off any ringing sound from an open hi-hat (Note 46), replicating physical drum playability.

Hardware and Playback Requirements

To fully support the GM1 sound set bank arrangement, compliant sound modules and synthesizers must adhere to strict minimum performance standards: