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MIDI Part Deux

Last month’s article was a basic introduction to MIDI. This month’s article concerns how different MIDI instruments and gear communicate with each other. Just about every piece of musical gear now comes with MIDI ports and whether they be the old school round connectors or the newer USB type, they both perform the same functions. 1) transferring MIDI data and control messages from a keyboard to a synthesizer (either hardware or software), 2)controlling remote gear including lighting, recording gear and other keyboard and modules, 3) enabling software updates and backups and 4) synching up MIDI recording and playback devices. .

Let’s look at the most common use for MIDI—hooking up a MIDI keyboard or device to outboard sound modules such as synthesizers or drum modules. Each MIDI device has MIDI in and out ports and sometimes’ MIDI through ports. The MIDI out port for the keyboard or device is connected to the MIDI in port for the sound module. TA– DA! You should be able to play a note on the keyboard and the sound module will respond by sounding the note. The cool thing is that you can daisy chain sound modules using the through ports and MIDI channels. For instance, you’ve got keyboard workstation like Roland’s Fantom that transmits data on 16 midi channels. You can play a piano part on the Fantom, while transmitting MIDI data to another sound module on channel 2 and to a drum sampler on channel 10 and control the lighting for your gig on another channel. The out port from the Fantom is connected to the in port of the sound module and the sound module is set to receive on channel 2 so it only plays back the data transmitted on channel 2. The through port on the sound module echoes the data sent to the sound module’s in port and is connected to the in port on the drum sampler that only receives and plays back data on channel 10 but it echoes the data to it’s through port and sends the information on to the lighting rig on channel 16 or whatever channel you choose. You can also differentiate gear by assigning it a unique device number. In effect, the keyboardist can play the keyboard, horn parts, drums and control the lighting.

The next most common use for MIDI data is to synchronize recording and playback devices to a common time code. There are several formats including SMPTE, MMC and MTC. SMPTE is a format developed by the Society for Motion Picture and Television Engineers to sync up film and sound by referring a common frame number. Regular movie film uses 24 frames per second and American television uses 30 frames per second. It got co-opted by audio recording studios to sync up two 24 track recorders, for instance, and is utilized in hardware and software sequencers to sync up to outboard recording and playback gear. MMC or Midi Machine Control is a format that allows control of playback and recording by remote devices. MTC or Midi Time Code is very similar to SMPTE but instead of using frames to synchronize to, it divides each musical measure by 24 and uses that to sync each device..

The least most common use for MIDI is to update the software of a piece of gear such as a guitar effects rig. By using a computer and an archiving program, you can dump the patches you’ve programmed on your Line 6 POD, etc onto your computer’s hard drive or tweak your settings in real-time from your computer. In practice, a guitar tech can change patches on the lead guitarist’s rig in between songs so that he (or she) only has to concentrate on playing.

Next Month—How sound modules and samplers work

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