I wonder if it's really possible to rebounce. Once 4 tracks are bounced down to one or two, it can't be undone IMO. Only if all the original tapes are saved: then all the single tracks could be written onto a new track in a 32 or 64 track digital machine.
It would be possible in the following scenario:
It's 1967!!!
FOUR TRACK ONE - Tape 1
contains 4 recorded tracks
copy those 4 tracks to 2 of the tracks on
|
FOUR TRACK TWO - Tape 2
now contains 2 recorded tracks
the 'spare' 2 tracks are later recorded
Now it's 2005!
You return to Tape 1 and copy those 4 tracks onto 4 individual tracks of a digi-multi-tracker. You then get Tape 2 and copy those 2 'spare' tracks to the digi-multi-tracker - and hey presto, you now have 6 individual tracks to play with.
Of course, if back in 1967, those 4 tracks were mixed down to just one track on Tape 2, you would then have 7 tracks to play with!!
Easy huh?!