hairy_hen said:

For anyone who's interested, take a listen to the '93 mix when R2 gets blasted by the Jawas, and listen to the rear-channel echo just after this. Now listen to the '85 and '77 stereo mixes: hey, that sound's not there! It isn't in the mono mix either, but it is in the SE's. Is it a '93 addition, or was it part of the 70mm version? I can't decide. The in-theatre 70mm recording doesn't seem to have it, at least not the one I have, but then that recording doesn't seem to have any of the surround effects at all, so that tells me nothing; also, the mono version completely omits everything that was in the surround channel of the others anyway, so again that's inconclusive. There's another sound like that during the shot of the Millennium Falcon in hyperspace, a sort of 'backdraft' or something in the surround, which is only heard in the '93 and no other. Again, I have no idea whether it was a part of the 70mm version or not. What to do, what to do . . .

Interesting, never noticed the difference before. When you describe them I know exactly what soundeffects you refer to. Damn, that's a tough decision on what to do, have you already checked David Morgan's audio files if any surrounds can be heard in those sequences? http://www.wideanglecloseup.com/starwarsaudio.html I'm not able to do so myself at the moment.