Perhaps the most compelling reason to equip a pipe-organ with MIDI is to permit the recording of organ performances. Of the many uses for a record/playback device or sequencer, perhaps the most valuable use of this feature is its use as a teaching tool. An organist can easily record a performance and then, while it is playing back, walk around the building an listen to the performance exactly as the audience would hear it. Since many sequencers are, in fact, personal computers, it is possible to transcribe a musical performance onto paper, given the appropriate software on the computer. Some sequencers such as the Viscount RD-70 or Yamaha MDF3 are ideal record/playback devices, partly because they save the recordings on 3.5-inch floppy discs, using what is known as “Standard MIDI Play Files”. These disks can be read directly on Windows-type computers, where the recordings can be edited or transcribed using whatever sequencer or transcription software the user is comfortable with.

MIDI record/playback devices or sequencers record every aspect of the performance, including all the note on/off data, the manuals used, the swell-shoe operation and all the stop changes. Since the control of an organ is rather different from the control of most MIDI sequencers and expanders, in keeping with its philosophy of providing maximum flexibility to the organist, Classic Organ Works provides sequencer-MIDI support completely separately from its expander-MIDI support.

The Classic Console Control Computer has at least two sets of MIDI in/out sockets or ports – one for expanders and one for a sequencer. For the sequencer, the note and expression data of each keyboard is on a separate MIDI channel: Great is on Channel-1, Pedal is on Channel-2, and so on (there are 16 channels available on GM-MIDI). Stop data is transmitted as a block of data known as a MIDI “System Exclusive” (SysEx) message whenever there is a major change as in the pressing of a General piston. When an individual stop is turned on or off manually, a MIDI “controller” message is transmitted to the sequencer. When the recording is played back, all notes, swell shoe movement, and all pipe, electronic and MIDI-stop changes are reproduced exactly as recorded previously.

A very useful feature of the Classic system is that, while a recording is being played back, the organist can actually play along or change registration on the organ at the same time. To further enhance this feature, a “MIDI Registration Off” control can be installed so the organist can prevent the organ from reproducing all the registration changes that were in the original recording.