Fang Zei said:
Speaking of Empire and Jedi, there's something I've been wondering. Were the original six-track versions 5.1, or were they 4.2 like Star Wars? There's a featurette on the Apocalypse Now complete dossier about how it was the first movie to be mixed/played in 5.1 when it opened in '79. Did every other six-track release from then on do the same thing?
According to the lists on in70mm, all the Star Wars films used the 4.2 format with twin LFE's and mono surround. Apparently stereo surround channels were quite uncommon before 1989, and didn't always correspond with use of the dynamic increase provided by Dolby SR.
http://in70mm.com/library/process/dolby/index.htm
These newer 70mm magnetic mixes could be described as 5.2, because for the sake of backwards compatibility they still used twin LFE's as did the older variant. The stereo surrounds were mixed into the LFE channels, relying on crossovers in the signal chain to separate the bass frequencies from the rear effects. A mono rear channel was also included for theatres that didn't have stereo surround capability.
(Note that present day DTS cinema format also encodes the bass into the surround channels to eliminate the extra bandwidth a separate LFE would require, but the home video DTS codec does not do this.)
Indiana Jones and the Last Crusade is listed as using both Dolby SR dynamics and stereo surrounds. I wonder if the 5.1 mix on the dvd is the same as the 70mm or if it was redone. I'm pretty sure Raiders of the Lost Ark was remixed, due to occasional stereo surround use, but I couldn't say whether it was done from scratch or came from modifying the existing 70mm version. Some have commented negatively on the dvd mix compared to the 35mm stereo, which might indicate its having been redone, but I'm not familiar enough with either to speak of it with any authority.