Movies in 70mm & 6 track magnetic Dolby Stereo

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atrocity

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(might be useful to determine if the DD/DTS 5.1 home video release is likely from the 6 track original or remixed)
I assume the "SS" notation means "Split Surround". I thought that by the 1980s pretty much any 6-track mix employed split surrounds
(i.e., 5.1) rather than five screen channels + mono surround, yet the titles marked "SS" seem to be in the minority'. Am I wrong/crazy again?
 

kfbkfb

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I don't know much about the surround sound methods and systems associated with movies, mainly just Dolby Stereo, DD, DTS et al.

Early in the Quad era (1972/73), the Disney "roadshow" presentation of Fantasia was often mentioned in articles to illustrate that surround sound wasn't an early 1970s idea, Fantasia was released in the early 1940s.


Kirk Bayne
 

MidiMagic

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I assume the "SS" notation means "Split Surround". I thought that by the 1980s pretty much any 6-track mix employed split surrounds
(i.e., 5.1) rather than five screen channels + mono surround, yet the titles marked "SS" seem to be in the minority'. Am I wrong/crazy again?

Why does everyone think the mono surround is a point source that can't be panned. I have panned sounds to one side or the other of the mono surround using DS matrix encoding.

I don't know much about the surround sound methods and systems associated with movies, mainly just Dolby Stereo, DD, DTS et al.

Early in the Quad era (1972/73), the Disney "roadshow" presentation of Fantasia was often mentioned in articles to illustrate that surround sound wasn't an early 1970s idea, Fantasia was released in the early 1940s.

Kirk Bayne

I have photos of the sound film from the original Fantasia in 1940. There were four variable width film soundtracks that used the entire width of the film. The DVD version I have is in Dolby Surround.
 

Owen Smith

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I have photos of the sound film from the original Fantasia in 1940. There were four variable width film soundtracks that used the entire width of the film. The DVD version I have is in Dolby Surround.
There were also notches cut into the edge of the soundtrack film to steer the 3 channels of actual music to different speakers. This was done manually in some theatres and automatically with the notches in others.

I have the Blu Ray of Fantasia and the original soundtrack is on that in DTS HD-MA 7.1
 
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atrocity

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Why does everyone think the mono surround is a point source that can't be panned. I have panned sounds to one side or the other of the mono surround using DS matrix encoding.
But I'm talking about soundtracks that were specifically mixed with separate surround channels. Cinerama had it early on, but other than that, surround was generally single-channel until the 1978 "Superman". Originally, 70mm tracks had five channels behind the screen (because screens were big in those days!) and mono surround. At some point after screens began shrinking, what we now think of as 5.1 came along.
 

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I did a quick Google search for compression/expansion NR systems, it seems that Dolby A was the first (in ~1965), I was wondering if Disney thought of developing/using something like the dBX wideband, high NR system to quiet the Fantasound optical soundtracks.


Kirk Bayne
 

Owen Smith

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I did a quick Google search for compression/expansion NR systems, it seems that Dolby A was the first (in ~1965), I was wondering if Disney thought of developing/using something like the dBX wideband, high NR system to quiet the Fantasound optical soundtracks.
The film with the music on had four optical tracks. Three had actual content on, the fourth was a control channel that played tones. This operated TOGAD or Tone Operated Gain ADjustment which controlled the gain applied to the other three tracks so that they could have wide dynamic range while avoiding quiet passages being spoiled by optical soundtrack noise. That sounds like a noise reduction scheme to me.
 
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Owen Smith

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Ironically what we have of Fantasia soundtrack now is not as high fidelity as the original soundtrack film. In the 1950s it was transferred to 4 channel magnetic surround and that was done across a road over telephone lines which lost high frequencies. What we have today is a painstaking restoration of an old 4 channel magnetic print. If we could find the original optical soundtack film it could be scanned and processed by computer to produce a better quality copy.
 

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Yes, the control tones, modern NR systems use the signal itself, that's what I was thinking about. I wonder why Disney didn't make the (IMHO) short leap to an NR system that used the signal itself.


Kirk Bayne
 

Owen Smith

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Yes, the control tones, modern NR systems use the signal itself, that's what I was thinking about. I wonder why Disney didn't make the (IMHO) short leap to an NR system that used the signal itself.
Because 1) they were innovating all this from scratch themselves starting from low fidelity mono audio and 2) all the hardware had to be made using valves (tubes in US English). Frankly it is amazing what Disney achieved with Fantasound given where things were when they started.
Note Disney also considered widescreen for the Fantasia picture format but they dropped it due to expense. They were decades ahead of the curve on ideas and innovation.
 

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I just sent in70mm.com an email requesting they add a related links section and include a link to QQ.


Kirk Bayne
 
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abby normal

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i suspect the losses in the sountrack quality [re: fantasia] were not so much in the treble RANGE [generally, optical soundtracks were limited to below 10k at best] but in other additive distortions that mag tape brought [additional and concatenated wow and flutter, modulation noise et al] on top of the distortions in the optical stripes.
 

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The Dolby 70mm process went through a number of changes, with many co-existing at the same time.

The first Dolby 70mm system was format #40 in the Dolby format code directory (*). Five channels across the screen with one surround channel combined with roll off curves at the low and high end. Almost identical to the 70mm theatrical layout of that of the 1950s and 60s as used by Todd-AO and others.

Format #41 added Dolby A noise reduction and ditched the more aggressive filtering.

Format #42 added what were called baby booms, later referred to as low frequency effects tracks, put in place of the mid left and mid right channels. True five channel up front mixes had become exceedingly rare by the mid-70s, while low frequency effects had become popular at the time thanks to the Sensurround process, and Universal wasn't allowing it to be used by other studios without a hefty price tag. So in steps Dolby. (There's actually a great back story on the creation of format #42).

Format #43 added split surrounds, but the layout was an interesting space saving process. As the mid left and rights had already been designated as baby booms in format #42, Dolby opted to share the two baby boom channels with the split surrounds. The split surrounds would be filtered in the low end, as the low end of those two channels continued to feed subwoofers, via dedicated low end content, per format #42. And a sixth mono surround track still went along for the ride, providing mono surrounds for 70mm theaters who had not upgraded to split surrounds. Split surround equipped theaters were rare at the start and took some time to build a bigger base. Many 70mm theaters never switched over.

(*) The Dolby coding itself is worth noting as they of course wanted theaters to play each print correctly. And with the projectionist having said information, and 70mm itself being considered a classier event.. this helped reduce running a given print in the wrong format.
 
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