Staff versus MIDI Channel
What is the relationship between staff and MIDI channel?
Each staff that you add to a NoteWorthy Composer song file must be assigned to a MIDI channel. When you start a new song, by default, the first staff of a song is assigned to MIDI Channel 1, the second staff is assigned to MIDI Channel 2, third staff to MIDI Channel 3, and so on.
Each MIDI device can support up to 16 MIDI channels. Each MIDI channel can only handle one instrument patch at a time. So, each unique instrument patch will need to be mapped to a different channel.
Sharing a MIDI channel
If you have more than one NWC staff that will use the same instrument, all of them can probably share the same MIDI channel. For example, if you have three staves that require a Violin instrument (Staff: Staff Properties, Instrument tab, Name: Violin), all three can probably be mapped to the same MIDI channel (Staff: Staff Properties, MIDI tab, Channel) with acceptable results. In this case, only the first staff should actually assign an instrument, since a MIDI channel is only capable of sounding one instrument at a time (although it can probably play multiple pitches at the same time).
In addition, the volume for all three staves must be the same in this configuration, since each staff is sharing the same MIDI channel. If you need independent volume control in each staff, this technique will not work. In this case, you should assign each staff to different, unique MIDI channels.
Reviewing your MIDI channel assignments
The Tools: Score Review command is an easy way to quickly review your MIDI channel assignments. When the Device and Channel columns are the same for two or more staves, then they are sharing a MIDI channel. In this case, only one staff should have a Patch assignment, and the others should show "---" in this column.
When things don't sound right
If you assign 2 staves with different instruments that are sharing the same MIDI channel, only one of the instruments will actually be played for both staves. So if you ever have a staff play back with a different instrument than you have assigned, check the staff to channel mappings.
Most sound cards have a percussion channel on Channel 10 (some have it on Channel 16). This channel will only play back percussion sounds and cannot be used for general instrument patches (the instrument patch command is often used to select different drum kits when sent on MIDI channel 10). The sample file drumref.nwc demonstrates the different pitches mapping to different percussion sounds for this channel.
When you have more than 15 staff parts
If you have a score with more than 15 parts, your primary option is to share MIDI channels using the technique described above. However, if you have more than one MIDI device in your system, an advanced option is to use more than one play back device to increase your number of available MIDI channels. This is configured from Tools: Options, MIDI tab, Devices used by play back, and then can be utilized in a staff using the Staff: Staff Properties, Midi, Play back device control. You should only try this if you are comfortable with this advanced technique, and are not planning to share your files with others that are not employing this technique.