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Author
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Topic: 6 Track Magnetic vs 6 Track Digital
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Manny Knowles
"What are these things and WHY are they BLUE???"
Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002
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posted 12-29-2010 12:10 PM
In defense of the current digital systems:
1. They made it practical to deliver 6-track mixes to everyone.
2. No special handling required in projection.
3. They are far superior to analog optical which, for most of us, is what they replaced.
AFAIK it was never the intention of the studios to bring 6-track magnetic to the masses, so I don't want people to read this thread and think "Gee! If only digital hadn't come along - we'd have better sound today." Because that is just not the case. If digital had not come along, we'd still be listening to analog optical through uncalibrated A-chains. Maybe in stereo. Maybe.
Mag was a format that was created and used for select (upscale) markets. The limitation was due to (a) the expense of the sounding process, (b) added cost of shipping, and (c) the special handling required in projection. It just wasn't practical or cost-effective to ship a 70mm mag striped print to every market.
So, I'm sorry if digital came along and ruined it for everyone living in the big cities. But, this "island boy" is VERY happy that digital came along and thinks it made movies sound better than they otherwise would sound for millions of people.
I would also argue that just as Dolby A made it possible for Ben Burtt to do everything he did with the "Star Wars" soundtrack, DTS made it possible for Gary Rydstrom to do what he did with the sound of "Jurassic Park." It is also worth raising the point that, given the transition to a digital post-production process (and now an all-digital workflow), a digital release provides an exact copy of the original whereas an analog copy would be something else.
Digital sound also helped to bring order to what was turning into a hot mess - look at all those different mag formats (see previous pages) and the dual-inventory (triple inventory if you also count 35mm).
Parting shot - I drove over an hour to see "Willow" in 70mm in its opening weekend when I lived in Detroit. The final reel had dropouts during the big climax when the evil queen is defeated. Very disappointing. As with CDS (previously mentioned) 70mm/mag has a great potential problem in that there is no backup track.
...and now, we wait for the flames! ![[evil]](graemlins/evil.gif)
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Bobby Henderson
"Ask me about Trajan."
Posts: 10973
From: Lawton, OK, USA
Registered: Apr 2001
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posted 12-29-2010 02:00 PM
quote: Manny Knowles
It is also worth raising the point that, given the transition to a digital post-production process (and now an all-digital workflow), a digital release provides an exact copy of the original whereas an analog copy would be something else.
Excellent point. I forgot all about generational loss. A 70mm Dolby SR mag audio track can sound fantastic, but its quality may be slightly different from the master mix tape and the master stems.
quote: Manny Knowles
Mag was a format that was created and used for select (upscale) markets. The limitation was due to (a) the expense of the sounding process, (b) added cost of shipping, and (c) the special handling required in projection. It just wasn't practical or cost-effective to ship a 70mm mag striped print to every market.
Standard 35mm release prints are produced at high speed. The image and audio is all duplicated in one shot. That's not the case with a mag striped 35mm or 70mm print. The image is duplicated to the print, the mag striping is added (and it has to cure, which takes more time), and then the print has to be "sounded," which is done in real time, not high speed.
The cost for producing the mag stripe print is really high, but the extra time required to produce the print is very costly as well. It's one thing to create a couple dozen or so 70mm mag stripe prints for key movie theaters. It's asking too much to create 2500 or more such prints for a general release. Some movie releases did have a lot of 70mm prints. Dick Tracy, Hoffa, Indiana Jones & the Last Crusade and Far and Away are a few movies I remember having 70mm engagements in many theaters.
Still, a movie with a couple hundred 70mm prints never was going to get its 6-track mix into as many theaters as a movie using one of the 35mm oriented digital processes.
Dolby was short-sighted in pricing and marketing 35mm Dolby Digital merely as a replacement for 70mm mag in "flagship" theaters. DTS had the philosophy that 6-track audio should be in every neighborhood theater. That gave the company a permanent foothold in the market. The downside to that philosophy is many neighborhood theaters couldn't present 6-track audio well. The 70mm equipped sites were able to do a better job with it. IMHO, many commercial movie theaters aren't doing their sound right today, even when the system is being fed an uncompressed 24-bit 5.1 d-cinema track.
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 12-29-2010 04:53 PM
I've come to the firm conclusion that the analog vs digital debate is best left alone (particularly on audio...where even analog vs analog or digital vs digital can take on violent arguments).
As a point of reference on the CDS 70mm...its "optical" sound area was INSIDE the perforations and wider than the inside mag track it replaced. As such, it encroached into the picture area. Since CDS was co-developed by ORC, which distributed Century projectors, at that time, they came out with a specail version of the 70mm runners that did not scuff the CDS track because they were milled thinner on the CDS side. Unless he has pitched it, Brad Miller had/has a fully functional CDS system. There would likely not be any patent issues with CDS, at this time as the patents have or will expire very soon (most likely have expired).
70mm in its modern form (5/70) always had 6-channels of sound available on the magnetic tracks. With the exception of an odd run of 2001 prints (or possibly one print) in the '90s, which had a 5.1 sound configuration (same track layout as on a 6-channel dubber), they all had the same track configuration. It was the processor that played those tracks differently. Track 1 (closest to the projectionist) was Left, track 2 was Left-Center, Track 3 was Center, Track 4 was Right-Center, Track 5 was Right and Track 6 was Surround.
Format 40 (all of the format NUMBERS were coined by Dolby for their CP200 processor that call up formats in that manner...yet the format numbers are still with us...long after the CP200's demise)...played the tracks in that way (5-screen channels and mono surrounds). Format 41 was the same but with NR applied (mostly type A but starting in the late '80s and into the '90s SR was used).
Format 42, which was probably the most popular Dolby Stereo format...aka baby boom...used the same track configuration as above but encoded a compressed bass track on tracks 2 and 4. If you have a non-Dolby theatre...aside from the lack of noise reduction, the compressed bass fed the LC and RC speakers. If you had a Dolby processor (CP100 w/Cat 105D or CP200), then LC and RC received the bass signals but the signal was expanded back to its proper dynamics and improved bass response as well as the LC/RC speakers could provide. In typical cinemas of the day, they would be Altec A4s...which could, with their bass-wings play reasonably flat down to 40Hz...with their 108dB 1-watt/1-meter sensitivity and by combining both speakers on just the bass, could decently augment the system with more bass level without distorting the dialog/music and also without blowing themselves up! With the CP200, the notion of a dedicated subwoofer channel came about though some had already started to connect subwoofers to the LC/RC outputs prior to the CP200 to extend the bass response below 40Hz.
Prior to the CP200's debut in 1980, format 43 came about which was 70mm's version of stereo surrounds. It was quite clever and fully backward compatible. It used tracks 2 and 4 for both Ls/Rs and for the "bass enhancement" or "baby-boom." Track 6 still contained the full mono-surround track. What allowed it to work was the Cat 158 which was really a purpose built crossover and summer. It took the signals below 250Hz on LC and RC and sent them to the LC/RC outputs and the signals above 500Hz (note the significant gap between the two cutoffs so little to no leakage between the channels) were sent to Ls/Rs (aka P and Q) respectively. However, the Cat 158 also took the mono-surround information off of track 6 and mixed that onto BOTH Ls and Rs for the frequencies below 500Hz (thus making them full-range but only stereo above 500Hz). So lets say this print shows up in a "non stereo surround" theatre. No problem, if it has a Dolby processor, LC/RC only play below 250Hz so the Ls/Rs information is ignored and track 6 plays as normal. If the theatre lacks any Dolby equipment...all one need do is disconnect the HF drivers on LC and RC since, at that time, all cinema crossovers were at 500Hz and again, only the bass information will play from the LC/RC speakers (though it will be compressed). It was quite elegant for what it was. They took advantage of the fact that we mostly hear higher frequencies directionally.
So yes, the modern 70mm (from 1954 onward) always had the option of 6-channels of sound (minimum). DTS-70 has, depending on the title offered 5.1 mixes or, in the case of films like Playtime the original 6-track mix.
As to panned dialog...it is severely lacking in modern movies but it was the norm in the '50s and '60s. I, personally, find it VERY distracting to have the sound separated from the actor (or object) by very much distance. I mostly fault Dolby with this as the hard-center dialog seemed to coincide with the arrival of the SVA system that could not pan dialog well. Dolby definitely discouraged its use. One problem panned dialog had/has is a lack of screen channels. With 5, the screen is pretty well covered. With three, the norm in most stereo movies, the holes in the coverage are pretty great. A phantomed LC/RC speaker will have issues and the effect will be greatly affected by where one is sitting, unlike when it is a physical speaker. Unfortunately, I don't think there are many out there now that know how to pan the dialog properly (there are techniques to panning dialog just like there are techniques on filming an image...like the 180-degree rule) to bring out its benefits without its issues. If you want good examples of panned dialog, listen to The Sound of Music and 2001:A Space Odyssey (the original 6-track mix). Heck the panned HAL into every channel! A good scene in 2001 to listen to is on the Orbiting space station while Heywood is in the phone booth talking to his daughter...you will see some cuts where the dialog does NOT suddenly shift since the character is off-screen...this keeps the timber constant and does not call attention to the shift...but, if the character is on-screen, the dialog follows.
-Steve
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Frank Angel
Film God
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 12-29-2010 05:33 PM
Full coat dual/interlock was used on any number of productions and with 35mm and as far back as THE HOUSE OF WAX (early 50s). True, these were not done in conventional houses, but only in certain markets and in flagship venues, but it is not a new idea and has been used through film history from the 50s on. All Cinerama presentations used 35mm full-coat interlock.
Also two points, the 12k trigger tone was used to turn ON the surround channel in 35mm mag prints -- not to turn it OFF. Nor was it used as a toggle as I have heard some (not here) claim. When the tone was present, the preamp was switched ON -- a HORRIBLE design. Horrible! as anyone who ever had to work with 35mm 4trk mag in a theatre will attest.
It could always be heard, no matter how good the 12kHz notch filter was, and if you DIDN'T hear it, that usually meant that the overall system wasn't reproducing the high end of the audio spectrum. To make it worse, it was recorded at full modulation - 0db. Even if you could filter it out of ch4, it would bleed into the coils of the adjacent heads in the playback cluster. Heads did get better, but not in the early penthouses. Later on 4trk mag's short life, the last of the 35mm 4trk releases did drop the trigger tone on the surround channel.
I have never heard it used to steer surround, although there is no reason why a Perspecta type system of tone controls couldn't easily have been adapted to steer track 4/surround on 35mm mag prints; but I never heard of the 12kHz tone being implemented in that way, and I have played many many Fox sprocket, 4trk mag prints.
And not to nit-pic, but it's called magnetic, not because the sound is "recorded on a magnetic strip" or because the film has "magnetic oxide stripes;" those stripes laid down on the film are IRON oxide - they are magnetically inert, if you will --they have no magnetism at all -- instead, they are a magnetism receptor. The soundtrack itself is imposed as magnetic variations onto the oxide in the recording process, magnetizing it as audio modulation. We call them mag stripes the same way we call recording tape "magnetic tape,' but to be clear, blank magnetic tape has no magnetism until something is recorded onto it -- same with the "mag" stripes on the film.
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Stephen Furley
Film God
Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002
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posted 12-29-2010 07:20 PM
quote: Mitchell Dvoskin
I am unaware of any 35mm mag stereo with surround steering, although I would not rule anything out. Many 35mm mag tracks had a tone on the surround track that caused the preamp to cut out the surround channel when present. This was done to eliminate hiss on that track, as mag stereo pre-dates Dolby by 2 decades.
Mitchell, haven't seen you for a long time. I was over there during the snow in February, but I didn't see you then.
It depends on what you mean by '35mm mag stereo with surround steering', are you talking about fullcoat or striped prints, but what about the mag striped 35mm prints of 'Around the World in 80 days' which used Perspecta on the mono surround track? I think that the infamous 34mm print of this film which ran at the Astoria Theatre Charing Cross Road in London also used Perspecta on the surround channel, but I'm not absolutely certain. There is a picture of the box as equipped for that film, and an integrator can be seen, but I'm not sure if it was used for that film. The 34mm print didn't leave enough room for conventional stripes, so the sound was run on interlocked sep-mag, but Idon't know if that was also 34mm, or 35mm.
Strangely, it seems that this wasn't used on the 70mm prints.
After many years as a night club that theatre was demolished a year or so ago.
quote: Frank Angel
Full coat dual/interlock was used on any number of productions and with 35mm and as far back as THE HOUSE OF WAX (early 50s). True, these were not done in conventional houses, but only in certain markets and in flagship venues, but it is not a new idea and has been used through film history from the 50s on. All Cinerama presentations used 35mm full-coat interlock.
Frank,
Some of the 3-D shorts shown in the 'Telekinema' at the Festival of Britain in 1951 originally had stereophonic magnetic tracks, but these are thought to no longer exist, and the films when occasionally shown now have only the mono optical backup tracks. Also, these were not feature films, and were basically just demonstration of the process.
quote: Frank Angel
Also two points, the 12k trigger tone was used to turn ON the surround channel in 35mm mag prints -- not to turn it OFF. Nor was it used as a toggle as I have heard some (not here) claim. When the tone was present, the preamp was switched ON -- a HORRIBLE design. Horrible! as anyone who ever had to work with 35mm 4trk mag in a theatre will attest.
I remember it well. One advantage of my hearing loss with age is that I probably wouldn't be able to hear it now.
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Tom Petrov
Five Guys Lover
Posts: 1121
From: El Paso, TX
Registered: Jan 2003
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posted 12-29-2010 08:08 PM
quote: Monte L Fullmer
Big thing being no upcharge for seeing either a 35 or 70mm release...and you got the better presentation with 70mm
Tiff Lightbox does charge an upcharge on tickets for 70mm presentations. $12 for 35mm, $15 for 70mm.
quote: Monte L Fullmer
Isn't this amazing that the world of the 70mm presentation still contains the wonder and awe after all these years compared if the same feature (if so available) is advertised to be presented in digital 3D,which now contain the "whatever" attribute?
Well, I won't lie. I was amazed by 2001 and Play Time re-affirmed my amazement. Last time I saw a 70mm was a blow up back in 1993.
I do have to add that part of the amazement and thrill was of the rarity, making a special trip and going down by train, having a projectionist run the show reel-to-reel, having curtains opening up while the theatre is dark and you are awaiting the first image etc. Also, like I mentioned earlier, the sound mix was impressive, or more important was the clear seperation of the channels, its been a long time since I heard a 35mm print sound as impressive.
Lastly, I should add that Tiff Cinema #1 is state-of-the-art and the closest thing it reminds me of is a classic THX sounding theatre, Tiff #1 is perhaps the best screening room in the GTA.
You notice right as you enter the cinema how all outside sound is non existent in the hallways of the theatre. The acoustics are impressive.
It is just the overall design that is impressive. To see every single seat pointed towards the centre of the screen is worth price of admission IMO, new stadiums seatings do not get this right. Also, the stadium rises very gently, its more like a slope with steps, very mild rise. All seats are fabric with no exposed plastic parts except for the the circle cupholder part. Armrests are padded.
All of these things (including 70mm) add up to an incredible movie going experience that a Silver City or Cineplex just can replicate.
I will be seeing two 35mm films at Tiff next week. I will let everyone know how they go.
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