You find out who performed those parts from the AFM (Some of them may well still be around so you can ask them questions)
Ford A. Thaxton
I thought Goldsmith did the synth parts himself at home on a couple of ARPs and a 4-track, a la Logan's Run. I'd bet those old tapes still exist somewhere long forgotten at the bottom of a box... unless his entire personal collection has been professionally archived by now. In which case they should have turned up.
I suppose both versions could be included; with and without synths.
How long does the existing orchestral parts of the score last for?
Could both with and without synths be included on one CD, or would it need two?
It's quite a short score, only around 26 minutes, so there would be plenty of room for alternatives. Could be that's the drawback to taking the effort to restore it - the CD would be too short. They'd have to consider taking on another title to add to it, at additional expense. Shamus was another short score, maybe that could be paired with it. I seem to recall that Prometheus intended to release Shamus years ago, but did Contract on Cherry Street instead when they found the tapes to Shamus to be in bad shape. Not missing, just in need of restoration, which perhaps is more possible now than it was then. Or is Shamus in fact altogether missing?
There are some obvious synth effects on the track 'After The Holocaust' from the Varese Goldsmith box. So presuming all the electronic effects were recorded the same way, and at the same time, it's strange that they appear on this track but are missing for others.
