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50 Years Ago in the Journal

The May 1954 Journal reported in “Progress Committee Report” by Charles R. Daily: “...The four magnetic stripes used on CinemaScope tremendously expanded the use of striped magnetic sound films. Reeves Soundcraft produced a new striping machine for Twentieth Century-Fox Film which applies the four magnetic soundtracks to the color release prints at 150 ft/min. The machine uses the familiar method of flowing a suspension of magnetic oxide onto the film from a properly shaped and calibrated orifice. Reeves Soundcraft have made available pre-striped raw stock in a variety of combinations including 35mm and 16mm sound-recording negative, Panchromatic and certain reversal color films. The sound recording material is used by Columbia and others to record simultaneously an optical track and a magnetic track on the same film. The optical track is then used in editing and the final mix is made from the magnetic stripe, thus preserving the quality advantage of the magnetic system for the final mix.”

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Posted by David Graham Rose (Member # 1450) on 06-14-2004, 02:02 PM:
 
Greetings to you Stephen

Not entirely sure where one would go for his type of service in the UK, but one could try Bell Theatre Services. They seem to have a great deal of equipment available whenever I need any specialist loops recorded. They can be found at 9b Chester Road, Borehamwood, England, WD6 1LT. Tel 020 8238 6000.

I'm sure that if Graham there can't assist then he will inevitably know someone who does, or will tell you in detail about facilities that were able to offer this service in the past.

From a warm Summers Eve in Cambridge, I bid you Good Evening

David
 

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Posted by Michael Schaffer (Member # 1204) on 06-14-2004, 03:28 PM:
 
Somebody told me that they can`t make magnetic striped film in california anymore for environmental reasons, but I don`t recall the details. Am I confusing this or is it true?
 

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Posted by John Pytlak (Member # 331) on 06-14-2004, 04:05 PM:
 
It's not that you can't, it's just that the cost of recovering the solvent vapors to meet current environmental standards is cost-prohibitive, and the small volumes of striping just didn't justify the capital investment required.
 

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Posted by Frank Angel (Member # 248) on 06-14-2004, 07:49 PM:
 
Steve is right, the ref tones on mag test film were really to balance everything out, not to actually eq anything as is done with the Dolby 1/3rd eq Cats in the analog CP playback.

Which brings up another question: am I correct in saying that the 1/3rd octave eq on the analog CPs is only applied to the optical sync sound? So this would mean that the mag tracks that are passed through the CPs are not 3rd octave eq-ed? Wouldn't this put the mag tracks at a decided disadvantage? Couldn't an outboard 1/3rd octave eq be employed to do what the 1/3rd octave eq does for the optical tracks?

In our house the system is already 1/3rd octave eq-ed for the B-chain as the projection system is only a subsystem of the entire audio system. The CP 1/3rd octave eq is only used to compensate for the optical playback anomalies in the A-Chain (very little is really needed -- almost all the controls except at the extremes wind up being pretty much at 0). The projection output is tweaked to flat for input to the main system and it is in the main system where the room is voiced at 1/6th octave digitally.

One of my friends was interested in getting pink noise into his mag system as he was using mag preamps from old Skully 4 track, 1in studio tape decks. They have high and low end eq as well as head-gap compensation. Without either a tone sweep test film or some pink noise film, there was no way to adjust these variables. What he did was, he took a unit designed to allow a portable CD to play in a car radio through its cassette deck.

Basically what it is, is a transducer head that the audio signal energizes and which is pressed up against the playback head of the cassette deck and thus the audio signal is induced into the head same as if the tape were inducing it. My friend used a regular pink noise generator to input the signal to this induction unit and then pressed the induction head against the mag playback heads, each in turn, in the penthouse. I wasn't there to actually see the results, but he was ecstatic and claimed it was a great help in adjusting the head levels and setting the mag preamp eqs. Steve, maybe could rig something like that. It might be easier than hunting around for old test film that probably isn't much more reliable for retaining accurate reference levels of flux across the tracks than your old stuff is. Magnetism is an elusive property....sometimes it sticks, sometimes it doesn't.

In the early days of CinemaScope 4trk mag prints, there were tales of prints getting their mag levels attenuated merely by shipping them back and forth across the Rockies; supposedly the earth's magnetism over a number of passes could actually act as a giant degausser. I don't know if this could actually happen or it was just a lab's excuse for sending out a print that had below spec low levels, but I heard this from a number of old timers. Seems to me tapes are sent back and forth cross country all the time without such dire consequences. But I repeat the story here because it was told to me as a green kid, and now that I am on the verge of old-foggie-ism, I get to tell these tall tails to the younguns.
 

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Posted by Rick Hunter (Member # 1606) on 06-14-2004, 08:05 PM:
 
There is the tale from the 'old days' where the projectionist managed to partly erase a mag print by transporting it from the exchange to the theatre here in Melbourne by tram.
The magnetic fields from the traction motors did the dastardly deed.
A lesson well learnt.

Regards,
Rick
 

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Posted by Steve Kraus (Member # 476) on 06-15-2004, 12:29 AM:
 
Likely an urban legend. How many transit systems use mag stripe fare cards? What about all those credit cards with mag stripes in people's wallets? I think the frame structure of the motor would mostly contain the high strength field just as it does on a transformer. Close contact perhaps...but sitting meters away with intervening structure which is likely ferrous? Doesn't seem likely although one never says never.
 

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Posted by Rick Hunter (Member # 1606) on 06-15-2004, 04:07 AM:
 
Alas, Steve, it is true.
I am talking of the early sixties where we only had money, not credit cards, and with the film cans sitting on the wooden floor of the tram the motor is was only a foot or so away.
I am not talking of complete erasure but major loss on what were the outer layers of film on the 'motor' side of the reels.
The print had to be sent back to the states for re-recording.

Rick
 

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Posted by Steve Guttag (Member # 268) on 06-15-2004, 07:04 AM:
 
Frank,

You are only partially correct...

Depending on the analog optical processor, EQ is applied to all formats or only the optical soundtrack.

For instance, the CP-50 only applied processing to the optical soundtrack and allow magnetic to pass-through. The CP-50 was always considered an add-on processor to an existing system. Note, if you didn't order the CP-50R, you didn't even get the ability to control volume either since many theatres had existing volume controls.

However with full-fledged processors like the CP-100, CP-200, CP-55 and later...EQ is applied to all formats.

In the days of magnetic sound prior to Dolby, things were much more wild. The system depended on the room response to set the tonal qualities. Back then, most any quality theatre was using an Altec A-4 (or A-5 if smaller) and most of them were barns. As such, speaker wise there was more uniformity then than THX has ever had now. When the films were mixed, they were mixed to such rooms. Any emphasis that was needed was done at the recording stage since they were mixing to the old rooms, sans EQ.

This subject has caused great problems with people that see the lack of a specified response curve to mean everyone should not apply any pre-emphasis and thereby not de-emphasize the track on playback. The truth is when you are mixing a film to a non-EQed system, you are going to sweeten the sound until it sounds natural to you. As such, if the playback speakers are rolled off by the screen and their natural response, the recording engineer is going to compensate by ear to make it sound natural.

If you play back that track in a like environment...it too will sound natural.

If you take that same track, play it back on a system tuned to today's specs (ISO 2969/X-curve) it will sound quite harsh and hissy. BTW...the same sort of effect will occur in the bass region too.

In Dolby's CP-200, when you select format 40 (or 20/22), it will apply a bit of an HF roll off to mimick the response of an old theatre sans-EQ. Even on the CP-55, on the Mag inputs, there was a 4.5K LPF to tone down the HF response. Even though the Cat. 242 never received a suffix of A or B...etc...when the CP-65 came out, the roll off was removed since 4-track mag was more rare than needing the extra input for something else.

Now this would lead some to believe that all they need to do is nix the EQ for playing back old films...nope...two of the missing parts of the equation are the Altec speakers and the old room response.

I recently was afforded the opportunity to work with an old 1950s/1960s system (70mm) that was essentially unmolested except for the Solid State amps had replaced the Altec Tube amps. Listening to a 1957 film through the system did NOT have much if any apparent hiss or spittiness. The vocals sounded clean and natural. The music had that 1950s sound.

What was nifty was that this is a back-to-back theatre with identical theatres running the same film on both sides.

I upgraded one theatre to a modern 70mm processor and playback. All was tuned to THX perfection. The same 70mm film was nearly unlistenable with the new equipment. The moment the sound was unmuted on the film...HISS assaulted the ears and the dialogue was anything but natural and it was quite spitty.

Here we had a missmatch...old recording, new system. So I applied a roll-off that approximated the X-curve to the Magnetic A-chain...result...no-hiss, natural sound and more detail than ever before. All this with a non-Dolby encoded print. At this point one could compare the two theatres and the new system was considered to be an improvement now for ALL formats. The other theatre was similarly converted.

So there is your long winded answer...EQ is done to equalize a room, not a track...however both the recording and playback end of things MUST have a similar response (identical if possible) if the intended sound is to be reproduced properly.

Steve
 

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Posted by Frank Angel (Member # 248) on 06-15-2004, 10:15 AM:
 
Steve, as always, very enlightening. I guess the idea of referencing each system to a standard curve -- applying it in the recording system in the mixing studio and the same reference in the theatre playback system, regardless of the room acoustics in either place, was a very smart industry move. I suppose Dolby can take credit for it, but I do recall it was in an Altec brochure that I first saw their promotion for what they dubbed their "Theatre Voicing" that concept which was just an ungainly looking 1/3rd octave stand-alone equalizer. Of course not everything can be fixed with room eq, but they were on the right track and I imagine this was around the early 70s, before Dolby's entry into cinema sound.

We have one of those barns -- 2500 seats and, yes, the entire system back then was Altec. An Altec audio mixer (12 channel with those big round knobs on pots for faders instead of sliding faders), double Voice of the Theatres for each channel with additional multisectional HF horns in the center aimed at the far mezzanine and the balcony, all driven by those beautiful Altec tube amps, what were they 1580s? -- four 6L6s in parallel push-pull output and something like 100 watts each, if that. But by George, we got plenty of sound out of that super efficient system and best of all, the sound was meeelllllooooow. And everything was Altec green.

And what you are saying about mixing engineers mixing for the known, general acoustics of the existing rooms does hold true because I distinctly remember a 900 seat Century theatre in Fresh Meadows, NY where I frequented as a kid, and I recall that occasionally I would hear this fairly loud THUD, which I came to know later was the sound of a splice. But strangly, although today we do backflips to eliminate that occurrance, back then, even THAT sound had a warm, "friendly" character to it. I actually used to like to hear when it happened. So you are right, the combination worked well in those days. But the problem is, as you say, that uniformity of theatre and system design has gone the way of the movie palaces themselves.

We do play quite a number of mag prints and luckily our booth channel outputs run to a mixing console, so I have the luxury of parametrics on each channel and it is not an arbitrary reference but basically my ears that are the final determination of how to eq the tracks on a mag print. We can get almost any track, even the ones that sound like fingernails on a blackboard to sound, if not great, then at least listenable in that space.
 

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Posted by Stephen Furley (Member # 1277) on 06-15-2004, 10:26 AM:
 
Frank, What's happening to your place? Have you re-opened after the refubishment yet? Whereabouts in Brooklyn are you? I'll have to come and see you sometime.
 

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Posted by Frank Angel (Member # 248) on 06-23-2004, 06:17 PM:
 
Steve,

We are in central Brooklyn (the Flatbush section) and no, we are not opened yet for a regular a film program. The renovation is going on in phases. Before we get to the end of each phase, we run out of money and then they have to find more. A new sound system is going into place over the summer as is the seat refurbishment. We have a completely new lobby that has to go in during the fall and I think rugs and wall facing go in in the winter. I am told I can run film occasionally, but only during the breaks between each phase.

There are something like ten contractors all involved with this project and all are supposed to be synchronized so when one is done, the next one takes over -- if one delays everything gets screwed up. The administrations sees this nice calendar plan on paper and actually believes it is going to work. I look at it and recall what a nightmare just putting an extension on a garage was and I figure if I get to run a film here and there in this facility by next summer I will be lucky.

But you certainly are welcome to come visit. I am doing films in Prospect Park this summer which is a fun venue. Come by and climb up on our scaffolding booth....good stuff.
 

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