How the film is mastered will make the biggest difference. The bad thing about most 70mm mag prints is that those 4.2 and 5.1 mixes were largely derived from the 4 track master used to make the optical 35mm matrix stereo track. You don't get very much dynamic range from that.

Generally the 70mm mix differs substantially from the SVA mix in terms of stereo "width" and dynamic range. This varies of course from title to title depending on the mixers and on how much time was put into it. Less so on those films where there were only a couple of blowups made. I wouldn't make a blanket statement that the typical 70mm printmaster probably lacks oomph. Quite the contrary!

It is true that DolbySR magnetic has 22db of headroom versus the 20db of 16-bit digital. But the format is only going to be as good as the mix being recorded to it. If it is hamstrung already by compromises over the 35mm matrix, then that mix is not something appropriate for use on DVD.

When a film's source stems and other original elements are revisited, chances are far better in a really good 5.1 remix being possible. The source stems are not affected by release mix limitations. For instance, "Dances With Wolves" has a really great sounding 5.1 mix (in DTS or Dolby Digital) even though the film was originally released only in Dolby SR optical. But it did have 6-track SR stems and other material in mind for a potential 70mm release (that never was ordered). That source material was revisited to create a really powerful 5.1 mix.

A primary goal with the 80's-era 70mm blowups was to achieve better sound quality than the 35mm optical systems of that era could deliver. If the filmmakers knew they were going to release in both 35mm optical and 70mm mag (and assuming they are cutting costs by creating a single 4-track master mix), it seems like all they would have to do is create the highest quality 4-track master possible and use that for the 70mm mag. I mean, this should be no extra effort at all -- it's the master stems (or whatever they are called) mixed for 4-track. There's your superior mag release and everybody's happy. Then for 35mm optical, take that mix and run it through some kind of dynamic range limiter and filter to achieve a more conservative result that optical can deal with. Why would they have "processed" the 4-track mix for optical first, and then apply that compromised result to mag? Makes no sense.

It would be very interesting to see/hear some of those 70mm blowups today, delivered exactly as they were back then, and compare their sound quality against modern mixes and digital theater systems that we are now accustomed to. I suspect they would not fare well. I remember the editor of "The Absolute Sound" magazine used to rave about the superior sound quality of 50's and 60's roadshow movies with mag sound. I just don't believe it. If the sound was that good, how come the DVDs and laserdiscs of those movies always sound so "dated", as Widescreen Review likes to say.

The quality of 50's and 60's roadshow films may have been great, but I'm guessing some DVDs or laserdiscs could not get a great soundtrack. Mag must be cared for, or it will erase, suffer print-through, drop out, etc. I bet there are several titles where the orginal stems are bad, and there are no surviving mag prints from which to get a sound equal to the orginal quality.

Not true. In that period film mixes were made to separate 4-track DME stems which were then mixed down to a 2-track Lt Rt printmaster and, if 70mm prints were to be made, separately used to produce a 6-track print master with the addition of LF info for tracks 2 and 4.

"Since most major studios are recording their master mixes as separate four-track music, effects and dialogue stems, the dynamics of each section can be separately controlled during the print mastering step..." --- Larry Blake, sound mixer in "Recording-Engineer/Producer" June 1985.

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Did the print have any signs of "vinegar syndrome"? Mag striping may accelerate the onset of vinegar syndrome, and the acids released typically accelerate dye fading:
http://www.kodak.com/US/en/motion/support/technical/vinegar.shtml
http://www.kodak.com/US/en/motion/support/technical/molecular.shtml

That is NOT correct!

The technical paper "Color Negative and Color Positive Film for Motion Picture Use" by Wesley T. Hanson Jr., published in the March 1952 SMPTE Journal introduced the Eastman Color Film System. It was originally presented at the SMPTE Technical Conference on April 27, 1950. This film technology was unique to Kodak, and a great advancement over the German technology:
http://www.kodak.com/US/en/motion/about/chrono2.shtml

Kodak print film with greatly improved dark keeping was introduced in 1979:

EASTMAN Color LF Print film, 7378. Improved cyan dye post processing keeping. Process ECP. Markedly improved cyan dye dark-keeping stability. Discontinued January, 1982.
EASTMAN Color LFSP film, 7379. Same as 7378 except for Process ECP-2. Markedly improved cyan dye dark-keeping stability.1 Discontinued 1983.
http://www.kodak.com/US/en/motion/about/chrono3.shtml

And in 1982:

EASTMAN Color Print film, 7/5384 Improved cyan dye dark keeping and red sensitivity to process variations. Process ECP-2A. Replaced 7/5381, 7/5383, 7378, 7379. In SMPTE Journal December 1982 and BKSTS Journal August 1983.
http://www.kodak.com/US/en/motion/about/chrono4.shtml

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

We have break-out spacers that allow you to mount either a 35mm or 70mm reader on the same bracket (not at the same time, of course). We put a skinny spacer one on the 70mm and a fatter one on the 35mm. Then, a hefty thumb-screw to secure the reader to the bracket. All you have to do is then redjust the offset and you're ready to roll in a few minutes.

You only have to position the bracket on the projector once and that really saves time!

More information can be found in the online techcenter at www.dtsonline.com/cinema Look at DTS 70mm.

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Anyway, here's what Terry Beard said in 1993:

"One of the things that we want to happen when filmmakers start mixing movies for this format is to have them mix the movie without watching little red lights which indicate that they are crashing the Dolby Stereo matrix. As you know when people now mix a Dolby how they must often compromise. They manage the levels so that it will work for an optical release. They monitor through the 4-2-4 matrix while they are doing the mix. They mix this way because that is the way movies are released in the optical format. But with the format change to digital discrete release, the pictures are going to be mixed primarily for discrete digital playback.

For the new format the prime mix has almost no dynamic range restrictions. We developed and are providing equipment to the studios that will take the multichannel discrete digital mix and push it down in a very agreeable way to fit the dynamic range restrictions of stereo optical. It uses multiband limiters to compress the dynamic range. This piece of equipment does this in a very elegant way that is easy for studios to use.

Motion pictures are mixed now into the six-track release format intially in a four track discrete format (left, center, right and mono surround). This four track mix is spread to six tracks by splitting the surrounds and some additional effects and subwoof. The 35mm stereo optical is made by putting a dynamic range restricted master of the four-track discrete through a 4-2-4 box which encodes the four tracks down to two tracks which is decoded by the theatre's matrix decoder back to four tracks. That's the way things are normally done. What's going to happen is if they know they are going to do a 5.1 discrete release they will mix to that initially. That's what they did for "Jurassic Park." Afterwards they crunched it down to get it into the Dolby Stereo optical format. Universal Pictures had already licensed the Dolby logo to be used on "Jurassic Park" and the optical mix was matrixed the Dolby matrix.

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