But, really, SO WHAT? I can not imagine any real need to do such a thing, except to show that you can. (EDIT: Read on, I think I get it a little later.)
If you write the song on a computer, it's practically essential, at least to me. Then again, it forms the basis of my entire workflow. Maybe if I explain how I use it, it will make sense. This is how I do it - there are other options. If you do a lot of live playing, you can, as I think you said at the end, use 7 tracks for live instruments and also have the computer play along at mixdown. That does work, but that's not how I work.
Firstly, I always write my songs on the computer first. I use a MIDI sequencer and I have it control a collection of about 6-8 synthesizers. Okay, at a pinch I could probably record all the synthesizer tracks to a stereo pair, but that would mean no subsequent mixing would be possible.
There are two other limiting factors. Firstly, I have a couple of synthesizers that have quite limited polyphonic capability. A monophonic synthesizer which I like to use in both lead and bass roles, and an MVS-1 which has 28 notes of polyphony. Some of the voices are multi-layered so it doesn't actually take much use before it starts to run out. At this point, you have to multitrack it.
The other factor is the amount of MIDI traffic involved in driving all the synthesizers at once. I have three MIDI busses, but with the whole composition running at full tilt (and they can use 16-20 MIDI tracks at once) it starts to drop packets and the timing goes out of whack. It also makes it more difficult for the sequencer software to cope if you have a slower computer. Again, the solution to both is to split it up into segments and record them track by track.
So. You have a song with a bunch of tracks, say 6 instrument groups. It's being played automatically by the computer, especially if like me, you can't actually play an instrument yourself
If you lay it down track by track, it
has to start precisely on queue, and it has to remain in perfect sync or the tracks will drift apart from each other. That's where the sync box comes in, and believe me, I tried to do it without
At the end of the session, I have a tape with something like the following tracks:
1. Backup vocals
2. Bass (Pulse Monosynth)
3. Organ (Synth module)
4. Mellotron (Synth module)
5. Lead synth (Pulse again)
6. Drum machine
7. Lead vocals
8. timecode
...and that means that not only can I use the Pulse for two different purposes, but I can also independently control all those instruments at mixdown, rather than programming the mix in at tracking. It also means I can add effects and processing tailored to each track as they're recorded. If they were all done at once I'd have to have several independent delays if I wanted a different delay time on the lead synth as opposed to drums etc.
Anyway, that's what I do, and it would not work as well as it does if I didn't have the ability to lock the sequencer tracks up to tape via MIDI sync. Does it help?
EDIT:
If you want a real-life case scenario, I can show you one of my track layouts when I get home if you're interested.
