MIDI Channels MIDI Reception Modes Multi-Timbral Instruments

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MIDI Channels

All MIDI devices receive MIDI information at the MIDI In port. All MIDI channel message information has an identification of a specific MIDI channel. The second nibble of a MIDI byte has sixteen possibilities that identify the MIDI channel. In the example below, the first four digits (1100) represent a program change and the last four digits (1111), refer to MIDI channel 16.

Consider the analogy of a television set that has sixteen channels. All sixteen may be viewed, but only one channel may be on the screen at any given moment. A MIDI device may be set-up to respond in a similar fashion. It may receive information on all sixteen channels, but it only responds to one MIDI channel at time. The MIDI device will ignore all channel messages that do not correspond to the same MIDI channel. This type of reception mode is called Omni-Off Poly. Now, let's look at the four types of MIDI reception modes.
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MIDI Reception Modes

Mode 1 - Omni-On Poly - The receiving device listens and responds to all incoming MIDI channel data. The device will ignore the channel destination of each status byte and attempt to play all MIDI messages. Poly, is dependent on the number of voices that a MIDI device can play at any given moment in time. Some devices may only have eight note polyphonic capabilities, while other devices may play up to sixty-four voices simultaneously.

Mode 2 - Omni-On Mono - The receiving device listens and responds to all incoming MIDI channel data in the same fashion as Mode 1, though the instrument will only play one note at a time. The mode is not very practical and has little use in most MIDI applications.

Mode 3 - Omni-Off Poly - This is the most frequently used mode. The MIDI device will listen to all incoming channel data but only responds to information set to one particular channel. Poly is dependent on the number of voices that a MIDI device can play at any given moment in time. Some devices may only have eight note polyphonic capabilities, while other devices may play up to sixty-four voices simultaneously. If a device is multi-timbral, then it may be set-up to have more than one instrument playing simultaneously, and each instrument will play the notes polyphonically up to the device's limit.

Mode 4 - Omni-Off Mono - The MIDI device will listen to all incoming channel data but only responds to information set to one particular channel. It will only play one note at any given moment. A typical use for this mode is a MIDI Guitar Controller, where each string of the guitar is assigned to a separate MIDI channel and each string will play only one note at a time.

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Multi-Timbral Instruments

A multi-timbral MIDI device is able to respond to two or more different sounds simultaneously. It is like having two or more synthesizers combined into one device. A multi-timbral instrument can be set-up to play a piano sound on channel 1, a bass sound on channel two, a string sound on channel 3, and a solo instrument sound on channel 4. This type of device works well with a sequencer program that has specific information assigned to separate tracks, because each timbre ( program) will only respond to a specific MIDI channel.

In the example on the left, a sequencer application in the computer can send multiple tracks of MIDI notes on channels 1 through 10. The keyboard is set-up to respond to MIDI information on channels 1 through 3, while the multi-timbral device on the right is responding to MIDI information on channels 4 through 10.

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	What is MIDI?	MIDI Connections Java Enabled	MIDI Connections Non-Java
	Understanding Decimal Binary & Hexadecimal	The MIDI Language	Types of Data Transmitted through MIDI
	MIDI Channels and Modes	MIDI Controllers	General MIDI
	Standard MIDI Files	Using MIDI on a Web Site	Applications that use MIDI
	Audio vs. MIDI Files	MIDI Timing Concepts	Author Info and Comments

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