Seconding confusion about what exactly is being referred to . . . I did no filtering or boosting of low frequencies from the 2.0 soundtracks of any kind. Those I left strictly alone, except for minor alterations such as getting rid of the breaking glass in SW, etc. The '93 tracks have some cool bass in places, and I left them just as they were in the main channels where they belong. My LFE is derived from the special edition dvd 5.1 tracks and synchronised to the GOUT, and thus are true low frequency effects. I haven't done a frequency analysis but a lot of the content is definitely quite low, 30-40 hz range. By contrast what appears in the '93 mixes is largely mid/upper bass, more like 60-120 hz.

Just how much of the special edition LFE can be said to be original and how much was created anew, I'm not sure. Nearly all of it blends in very well with the main channels--it seems likely that at least some of it would have been in the 70mm soundtracks, beyond what already appears in the '93 mixes. The most obvious new effects were the ones that accompanied changed CGI shots--those I had to tone down significantly to get them to blend--and a few others had to be reduced as well, but less drastically. A couple times I actually boosted the volume, but those were less common.

Given how well the LFE integrates overall, I'm pretty sure that in many cases they simply took the original sound elements, pitch-shifted them downwards an octave or two, then amplified the hell out of them. I like to think that my results achieve a "70mm-ish" feel for the three movies, but I don't claim that this exactly represents those versions. It just sounds really cool. :)