Sound follower

File:Shadow_telecine_(6498603509).jpg in the center of the image]]

Many motion picture cameras do not record audio sound on the film, so in professional film production, there is a need to have the sound recorded and played back on a device that has a double-system recording to tapes, or by any means, for example DAT or Nagra, SD or other audio recording media and then transferred to 16 mm or 35 mm sprocketed magnetic film. The sound recording would then be synchronized with a movie projector

The primary goal is to achieve perfect timing of the audio track in relation to the visual footage. This can be achieved in two ways: Traditionally by recording a pilot track in an area of the tape that serves as a "clock" upon playback. This can be 60 Hz (in the US) or 50 Hz elsewhere, where there is a power line frequency of 50 Hz. In the studio, the playback of the original tape "pilotone" is compared to the power line frequency, and servo locks the playback machine to that power line frequency, while the Mag Film recorder's motor runs synchronously, transporting the 16 mm or 35 mm magnetic film being recorded.

The newer methods take advantage of the timing of the microprocessor clock accuracy, and rely on playback timing that is nearly absolute, for the length of a typical "take" anyway. Most 16 mm film loads are limited to 11 min, as the magazines typically hold 400 ft of film. This second method requires that the camera's drive system runs at a nearly absolute speed. Typically, this is achieved using a crystal frequency standard, which runs the camera motor. The motor drives sprocketed film, so there is no error from slippage, as found in the recording tape process.

[http://www.abctvgorehill.com.au/assets/photos/telecine_telerecord/tc-mag-replay-w.jpg abctvgorehill.com.au] mag unit at ABC in the 1950s, to play the sound locked to a film chain or a telecine. Either 35 mm or 16 mm film that is fully coated with a magnetic material can be locked, sprocket hole by sprocket hole, to the film with the picture image. On the set, a clapperboard is used to mark the spot where the sound and picture will later be aligned in editing.[http://www.soundonsound.com/sos/aug00/articles/audio.htm soundonsound.com] A Practical Guide To Working With Pictures, Part 3,Tips & Tricks, Published August 2000.

Typical sound followers lock to the power line using a sync motor and toothed timing belts, or by using {{val|240|ul=Hz}} bi-phase interlocking pulse signals to sync sound to film.[http://digitalpostservices.com/include/pdf/Glossary%20of%20Post%20Prodcution%20Terms.pdf digitalpostservices.com], Glossary of Film Terms The 240 Hz bi-phase is ten times the 24-frame rate.[http://www.glias.org.uk/glias/rws/pgs/r06.htm The Greater London Industrial Archaeology Society] Syncwriter 1983–1986, Film and Sepmag Sound followers are found in many post-production studios for record and playback and in movie theater for sound playback.[http://www.in70mm.com/newsletter/2005/70/leimeter/index.htm n70mm.com], Todd-AO studios, use of room full of Magnatech units in post production. In telecine use, the 24 frames per second is slowed to 23.976 frames/s to lock to SDTV and some HDTV standards, thus the digital bi-phase pulse is 239.76 Hz.[http://www.vtoldboys.com/tk_06.htm History of Telecine at the BBC, 1994]

The average feature film requires a large amount of 35 mm film. One second of 35 mm film uses 1.5 feet of film, moving at {{convert|18|in|cm|disp=x| per second (|/s)|0}}. One minute of film uses {{convert|90|ft|m|1}}, and one hour uses {{convert|5,400|ft|km|1}}. So, a two-hour movie with previews uses 11,250 feet or {{convert|2.13|mi|km|2}} of film. For 16 mm film, these numbers are all divided by 2.5 (36 ft/min.). Because a two-hour movie is so long, the whole is divided onto five or six reels. While a film projector uses an intermittent mechanism to play the film, a sound follower and most telecines use continuous motion.[http://www.editorsguild.com/v2/magazine/Newsletter/JanFeb03/tip_math.html The Editors Guild Magazine], "Math of Movies", Vol. 24, No. 1 – January/February 2003.

By having the sound and picture sync this way this clearly saves the expense and time of making an optical print or magnetic sound track strip on the edge of the film.[https://books.google.com/books?id=0ZmjkJwxyWcC&dq=Separate+magnetic+film+rca&pg=PA126 Sound recording], the life story of a technology, by David L. Morton, Jr. The Sepmag would follow a projector or a telecine or a hand-cranked or motorized film viewer on a workbench. The sepmag sound follower would stay in sync with the film. In post-production work, a dubbed sound track of sound effects, or a second language, could be added to other channels of the sepmag.*[https://books.google.com/books?id=fSHTldTq13YC&dq=Film+Sound+Follower+Recorder+Player&pg=PA174 Film into video: a guide to merging the technologies] by Stuart Blake Jones, Richard H. Kallenberger, George D. Cvjetnicanin, page 169 to 173

Sepmag had different record head configurations. A device could have a single mono track, dual two track or 4 track. The tracks are very large and the magnetic film moving at the normal speed of 24 frames per second, gave very good sound reproduction.[https://wikis.utexas.edu/display/comm/Mag+Dubber+in+4D+Control College of Communication – The University of Texas at Austin] How to use a Magnatech As such, a mixing studio would have many units, to mix all the sound and effect down to 4, 2 and one track as needed.[http://www.stanginsel.com/?p=170 Stan Ginsel, Video Producer] Classic Movie Making – What’s a Dubber and Mag Stock?[http://www.editorsguild.com/v2/magazine/Newsletter/JanFeb04/janfeb04_mixing_console.html The Editors Guild Magazine] Vol. 25, No.1 page 126- January/February 2004, by Gregg Rudloff, Film Mixing.

Magnetic film used is 3 to 5 mils thick, the same as the picture film, so the picture and sound have equal diameters on the film reels. The magnetic film has magnetic oxide coating on the complete width of the film. and the standard monaural track in 16 mm and 35 mm is 200 mils wide. 35 mm mag films may not be fully coated, but "striped" to permit editing marks to show through both sides.

The first films used were acetate base till 1970, then replaced by polyester base. Acetate base is unstable, can have degradation, the ferric oxide coating and the Acetate base can cause vinegar degradation.[http://presto.joanneum.ac.at/Public/D31.pdf Presto] Page 8, PRESTO – Preservation Technologies for European Broadcast Archives, IST-1999-20013, 3/05/2001[http://tech.ebu.ch/docs/tech/tech3289.pdf http://tech.ebu.ch/] Preservation and Reuse of Film material for television May 2001, page 5

In 1914, the first SEPMAG patent was filed. In 1929, the first sound follower was on the market and by 1941, AC biasing models were sold, giving better sound quality.[http://www.aes.org/e-lib/browse.cfm?elib=5074 Audio Engineering Society] AES E-Library

Magnetic Film Transport Based on the SEPMAG Method: Basis and Developmental Program from the First Unit up to the Present Time The Stille SEPMAG transport was one of the first SEPMAG systems.[http://www.aes.org/aeshc/books+vids/pre-1943.mag.hist.html Audio Engineering Society] Audio Technology in Berlin to 1943: Magnetic Sound Activities – Heinz H. K. Thiele Some of the older sound followers' interlock speeds were too slow to keep up with the high speed shuttle speeds of modern telecines; therefore, some 240 Hz bi-phase buffers were made to help solve this problem.

The major makers of sound followers are M.T.E.'s Magna Tech,[http://magna-tech.com/story.html magna-tech.com M.T.E history] RCA, and Sondor. Models can come in playback-only model or record-and-playback. Models can have the option of changing the number of tracks. Some are equipped with dual sets of sprockets that can use more than one size of magnetic film, 16 mm or 35 mm.[https://books.google.com/books?id=V8Lk2ghPl7IC&dq=Magnetic+Film+Transport+Based+on+the+SEPMAG&pg=PA459 National Association of Broadcasters Engineering Handbook], by Graham A. Jones, Edmund A. Williams, David H. Layer, Thomas G. Osenkowsky, pages 456–459.

• Magna Tech – M.T.E.
• SERIES 600, Electronic Film Recorders and Reproducers[http://magna-tech.com/mte600.htm magna-tech.com] SERIES 600
• Magna-Tech 835-B-6 600[https://www.youtube.com/watch?v=5-QIPjoxLjw youtube.com] Magna Tech 10036-3 Film Sound Follower Recorder Player.[http://www.fooooo.com/watch.php?id=5-QIPjoxLjw Magna Tech 10036-3 Film Sound Follower Recorder Player] {{webarchive|url=https://web.archive.org/web/20120323021050/http://www.fooooo.com/watch.php?id=5-QIPjoxLjw |date=2012-03-23 }}*[https://wikis.utexas.edu/display/comm/Mag+Dubber+in+4D+Control College of Communication – The University of Texas at Austin], How to use a Magnatech.[http://magna-tech.com/ http://magna-tech.com] Magnetic Film Recorders Stepper motor transport.
• Sondor
• OMA E[http://www.sondor.ch/oma_e.html sondor.ch] OMA E
• BASIC[http://www.sondor.ch/basic.html sondor.ch] BASIC
• SOUNDHOUSE[http://www.sondor.ch/soundhouse.html sondor.ch] SOUNDHOUSE
• Libra M03A[http://www.fonoteca.ch/yellow/devices_en.htm Swiss National Sound Archives]
• ALTRA[http://www.sondor.ch/files/pdf_manuals/ALTRA_handbook.pdf sondor.ch] ALTRA[http://www.summertone.com/products/magnetic-sound-follower.html Summertone on Sondor]
• MTM – Multi-Track Magnetics Inc.
• MTM D106/DCS-6[http://journal.smpte.org/content/84/10/local/advertising.pdf SMPTE] MTM add, page 5 Stepper motor transport.
• Ranger Tone[http://www.film-photo.eclipse.co.uk/gfx/eqmnt/RngerToneMTM.jpg Ranger Tone by MTM][http://journal.smpte.org/content/88/7/local/advertising.pdf journal.smpte.org] MTM add, page 517
• Rank Cintel
• FeRRIT[https://www.brunswickfilms.com/news/view.php?Id=118 brunswickfilms.com] Brunswick gets a Rank Cintel Ferrit, Sep. 18, 2009 Modern microprocessor transport control.
• MWA Nova GmbH – MWA Albrecht GmbH[http://www.damsmart.com.au/products/mwa damsmart.com.au] MWA-Nova history
• MB41[https://www.mwa-nova.com MWA Nova GmbH]
• MB51, Multi Format Magnetic Film Recorder/Player[http://www.flashscan8.us/MB51MagneticFilmRecorder.htm flashscan8.us] Model MB51[https://www.mwa-nova.com/products/sound_solutions/MB51.html www.mwa-nova.com/] MWA Albrecht GmbH, Model MB51[http://www.film-tech.com/warehouse/pics/hib100/HIB032.jpg film-tech.com] Magnatech
• RCA
• RCA PM85 6 Channel 35 mm Magnetic Film Recorder[http://journal.smpte.org/content/78/3/local/advertising.pdf SMPTE] RCA page 2, and Magna Tech page 19 Stepper motor transport
• TEAC
• TEAC 35 mm dubber[http://www.openreel.net/images/35dub.jpg openreel.net] TEAC 35 mm mag film sound recorder, 1968
• TEAC 16 mm dubber*[http://www.openreel.net/images/16dub.jpg openreel.net] TEAC 16 mm mag film sound recorder, 1968
• Steenbeck[http://www.steenbeck.com] http://www.steenbeck.com
• ST3514[http://www.steenbeck.com/3-9.html steenbeck.com] Steenbeck ST3514 with sepmag option
• Kinevox – Portable vacuum tube model, Burbank, California, CA[http://www.radiomuseum.org/dsp_hersteller_detail.cfm?company_id=11914 radiomuseum.org] Kinevox history
• Kinevox Synchronous Magnetic Film Recorder (pre-1951)[http://www.radiomuseum.org/r/kinevox_synchronous_magnetic_fil.html radiomuseum.org] Kinevox Synchronous Magnetic Film Recorder

Sound followers were also used in the 1960s strictly for audio recording & record album mastering, for the magnetic film format at the time had several advantages over standard magnetic recording tape. Magnetic film's extra thickness over tape made it less susceptible to "print-through", and its sprocket-driven nature made it less likely to suffer from tape flutter and other speed variations. Command Records in the 1960s released several albums that were recorded and mastered on 35 mm magnetic film for several artists on the label, such as Enoch Light, Tony Mottola, and others.

It is generally accepted that Everest Records subsidiary of the Belock Instrument Corporation based in College Point New York pioneered the use of three channel 35 mm magnetic film from around 1959. When the company transferred to Hollywood under new ownership in 1961 the Everest Bayside Recording Studio was sold and the 35 mm equipment to Mercury Records and later Command Classics. Improvements in standard tape technology and the high cost of the 35 mm process led to its discontinuance.{{cn|date=February 2024}}

Sound followers are not used for most new film productions (the major exception being IMAX). Sound followers are still in use, as there are many separate magnetic films in film vaults. Reel-to-reel tape, then later hard disk drive and solid-state drive recording system replaced sound followers.

{{div col|colwidth=19em}}

• Flatbed editor
• Film editing
• Film splicer
• History of multitrack recording
• List of film formats
• Movietone
• Phonofilm
• Photokinema
• RCA Photophone
• Recording studio
• Sound film
• Sound-on-disc
• Vitaphone

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{{Reflist}}

• [https://books.google.com/books?id=U9aH92iLEZAC&q=Separate+magnetic&pg=PA131 TV and Video Engineering, by A.M. Dhake].

{{Filmmaking}}

Category:Film production

Category:Film and video technology

Category:Film editing