MIDI specifies sixteen channels. Sometimes those channels are numbered 1–16 and sometimes 0–15. It can be confusing, so make sure you know your software’s channel numbering convention. This manual will number channels from 1 to 16.
MIDI channels exist so that you can separately control different parts of the music. For example, you can change the instrument on one channel while leaving the other channels alone. Or you can change the volume on only one channel to make it louder (or softer). Or you can mute a channel, or solo a channel (mute all the others).
You can create music for Gloria that only uses one channel. For example, if you connect a MIDI keyboard to your computer and record a musician playing a song then the entire song will typically be recorded on a single channel (say, channel 1), stored on a single track in a MIDI file (say, track 1). The computer software will probably add a tempo track (track 0) with nothing in it other than an initial default tempo that probably bears no relation to the actual tempo of the song. And it will most likely work in Gloria with no further modifications.
However, there are advantages to using multiple channels. While creating the music you can independently assign a different instrument to each channel. Flute for the melody part, acoustic bass guitar for the bass line, strings for the orchestra, for example. Also, users can themselves assign a different instrument to each channel in Gloria using the track keys (Melody, Alto, Tenor, Bass, Accompaniment) and the instrument keys. Users can also turn each channel on or off, or alter its volume relative to the other channels.
By MIDI convention, percussion lives on channel 10. Gloria has a complete General MIDI percussion set. All music commands on channel 10 are interpreted as percussion events (drums, cymbals, etc.). Instrument changes are ignored on channel 10.
This table shows how MIDI channels are used in Gloria:
| MIDI Channel | Gloria Key | User can change instruments |
|---|---|---|
| 1 | Melody | Yes |
| 2 | Alto | Yes |
| 3 | Tenor | Yes |
| 4 | Bass | Yes |
| 5 | Accompaniment | Yes |
| 6 | Accompaniment | Yes |
| 7 | Accompaniment | Yes |
| 8 | Accompaniment | Yes |
| 9 | Accompaniment | Yes |
| 10 | Percussion | No |
| 11 | Melody | Yes |
| 12 | Alto | Yes |
| 13 | Tenor | Yes |
| 14 | Bass | Yes |
| 15 | Accompaniment | Yes |
| 16 | Accompaniment | Yes |
A typical MIDI file created to accompany congregational singing will use six channels: melody, alto, tenor and bass on channels 1–4, accompaniment on channel 5 and percussion on channel 10. Simpler arrangements will sometimes skip accompaniment and percussion (channels 5 and 10).
You’ll note that two channels (1 and 11) are assigned to the Melody key, two channels to the Alto key, two to Tenor, two to Bass and seven channels to the Accompaniment key. Having two channels for Melody means you can use two different instruments simultaneously on the melody line for that song. MIDI only allows one instrument per channel at any given time. You can change instruments as often as you like on each channel, but each channel can only play using one instrument at a time. Multiple channels allow multiple instruments, which allow richer, more complex arrangements.
Keep in mind that those richer, more complex arrangements favour listening (a passive activity) but hinder singing (an active engagement). So consider your goals as you create the music: is it primarily for people to listen to, is it for backing tracks for professional, technically competent singers, or is it for accompanying the congregation at large? Gloria is often used at informal gatherings (e.g. hospital visits, retirement homes), so keep in mind the singing talent (or lack thereof) at such events.
A good arrangement is to record a single line of notes (monophonic) on each channel 1–4, chords of up to four notes (polyphonic) on channel 5, and (optionally) one to four percussion instruments at a time on channel 10. This allows users to listen to just one channel at a time (say, Alto) and learn their part.
A further consideration is that if you do use two melody channels to enable two different simultaneous instruments, if the user presses the Melody key on Gloria followed by an instrument key then both channels will be changed to the same user-selected instrument. The same applies to the other Gloria track keys, and most of all to the Accompaniment key: seven different channels using seven different instruments, suddenly all playing the same instrument. Having sixteen channels gives you a lot of flexibility in arranging your music, as long as you understand the limitations of Gloria’s user interface.