Sound follower

A sound follower, also referred to as separate magnetic, sepmag, magnetic film recorder, or mag dubber, is a device for the recording and playback of film sound that is recorded on magnetic film.[1][2] This device is locked or synchronized with the motion picture film containing the picture. A sound follower operates like an analog reel-to-reel audio tape recording, but using film, not magnetic tape. The unit can be switched from manual control to sync control, where it will follow the film with picture.[3]

Sound follower magnatech
Magna Tech, Electronic Film Recorders and Reproducer, SEPMAG


Shadow telecine (6498603509)
A Sound follower to the left of a Shadow Telecine

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, either DAT or Nagra, and then transferred to 16mm or 35mm separate magnetic film. The sound recording would then be synchronized with a movie projector[4] or a telecine. Either 35mm film or 16mm 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 synced.[5]

Typical sound followers lock by using 240 Hz bi-phase interlocking pulse signals to sync sound to film.[6] The 240 Hz bi-phase is ten times the 24-frame rate.[7] Sound followers are found in many post-production studios for record and playback and in movie theater for sound playback.[8] 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.[9]

The average feature film requires a large amount of 35mm film. One second of 35mm film uses 1.5 feet of film, moving at 18 inches per second (46 cm/s). One minute of film uses 90 feet (27.4 m), and one hour uses 5,400 feet (1.6 km). So, a two-hour movie with previews uses 11,250 feet or 2.13 miles (3.43 km) of film. For 16mm film, these numbers are all divided by 4. 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.[10]

By having the sound and picture sync this way this would save the expense and time of making an optical print or magnetic sound track strip on the edge of the film.[11] 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.[12]

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.[13] 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.[14][15]

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.[14] The first films use were acetate base till 1970, the next base was polyester base. Acetate base can have degradation, the ferric oxide coating and the Acetate base can cause vinegar degradation.[16][17]

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.[18] The Stille SEPMAG transport was one of the first SEPMAG systems.[19] 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,[20] 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, 16mm or 35mm.[21]

Alternate uses

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 35mm magnetic film for several artists on the label, such as Enoch Light, Tony Mottola, and others.


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.

See also


  1. ^ Audio post production for television and film an introduction to technology, By Hilary Wyatt, Tim Amyes, page 73
  2. ^ Georgia State University, How record heads work.
  3. ^ sepmag
  4. ^ mag unit at ABC in the 1950s, to play the sound locked to a Film chain
  5. ^ A Practical Guide To Working With Pictures, Part 3,Tips & Tricks, Published August 2000.
  6. ^, Glossary of Film Terms
  7. ^ The Greater London Industrial Archaeology Society Syncwriter 1983–1986, Film and Sepmag
  8. ^, Todd-AO studios, use of room full of Magnatech units in post production.
  9. ^ History of Telecine at the BBC, 1994
  10. ^ The Editors Guild Magazine, "Math of Movies", Vol. 24, No. 1 – January/February 2003.
  11. ^ Sound recording, the life story of a technology, by David L. Morton, Jr.
  12. ^ *Film into video: a guide to merging the technologies by Stuart Blake Jones, Richard H. Kallenberger, George D. Cvjetnicanin, page 169 to 173
  13. ^ College of Communication – The University of Texas at Austin How to use a Magnatech
  14. ^ a b Stan Ginsel, Video Producer Classic Movie Making – What’s a Dubber and Mag Stock?
  15. ^ The Editors Guild Magazine Vol. 25, No.1 page 126- January/February 2004, by Gregg Rudloff, Film Mixing.
  16. ^ Presto Page 8, PRESTO – Preservation Technologies for European Broadcast Archives, IST-1999-20013, 3/05/2001
  17. ^ Preservation and Reuse of Film material for television May 2001, page 5
  18. ^ 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
  19. ^ Audio Engineering Society Audio Technology in Berlin to 1943: Magnetic Sound Activities – Heinz H. K. Thiele
  20. ^ M.T.E history
  21. ^ National Association of Broadcasters Engineering Handbook, by Graham A. Jones, Edmund A. Williams, David H. Layer, Thomas G. Osenkowsky, pages 456-459.
  22. ^ SERIES 600
  23. ^ Magna Tech 10036-3 Film Sound Follower Recorder Player.
  24. ^ Magna Tech 10036-3 Film Sound Follower Recorder Player Archived 2012-03-23 at the Wayback Machine
  25. ^ *College of Communication – The University of Texas at Austin, How to use a Magnatech.
  26. ^ Magnetic Film Recorders
  27. ^ OMA E
  28. ^ BASIC
  30. ^ Swiss National Sound Archives
  31. ^ ALTRA
  32. ^ Summertone on Sondor
  33. ^ SMPTE MTM add, page 5
  34. ^ Ranger Tone by MTM
  35. ^ MTM add, page 517
  36. ^ Brunswick gets a Rank Cintel Ferrit, Sep. 18, 2009
  37. ^ MWA-Nova history
  38. ^ MWA Nova GmbH
  39. ^ Model MB51
  40. ^ MWA Albrecht GmbH, Model MB51
  41. ^ Magnatech
  42. ^ SMPTE RCA page 2, and Magna Tech page 19
  43. ^ TEAC 35mm mag film sound recorder, 1968
  44. ^ * TEAC 16mm mag film sound recorder, 1968
  45. ^ [1]
  46. ^ Steenbeck ST3514 with sepmag option
  47. ^ Kinevox history
  48. ^ Kinevox Synchronous Magnetic Film Recorder;

Auto-Tune is an audio processor created by Antares Audio Technologies which uses a proprietary device to measure and alter pitch in vocal and instrumental music recording and performances. It was originally intended to disguise or correct off-key inaccuracies, allowing vocal tracks to be perfectly tuned despite originally being slightly off-pitch.

Starting with Cher's 1998 hit "Believe", producers began to use Auto-Tune as a sound effect, to deliberately distort vocals. By 2018, music critic Simon Reynolds observed that Auto-Tune had "revolutionized popular music", calling its use for effects "the fad that just wouldn’t fade. Its use is now more entrenched than ever." The term auto-tune has become a generic term to describe audible pitch correction in music regardless of the method.

The effect is not to be confused with a vocoder or the talk box.


A concert is a live music performance in front of an audience. The performance may be by a single musician, sometimes then called a recital, or by a musical ensemble, such as an orchestra, choir, or band. Concerts are held in a wide variety and size of settings, from private houses and small nightclubs, dedicated concert halls, arenas and parks to large multipurpose buildings, and even sports stadiums. Indoor concerts held in the largest venues are sometimes called arena concerts or amphitheatre concerts. Informal names for a concert include show and gig.

Regardless of the venue, musicians usually perform on a stage. Concerts often require live event support with professional audio equipment. Before recorded music, concerts provided the main opportunity to hear musicians play.

Digital audio

Digital audio is sound that has been recorded in, or converted into, digital form. In digital audio, the sound wave of the audio signal is encoded as numerical samples in continuous sequence. For example, in CD audio, samples are taken 44100 times per second each with 16 bit sample depth. Digital audio is also the name for the entire technology of sound recording and reproduction using audio signals that have been encoded in digital form. Following significant advances in digital audio technology during the 1970s, it gradually replaced analog audio technology in many areas of audio engineering and telecommunications in the 1990s and 2000s.

In a digital audio system, an analog electrical signal representing the sound is converted with an analog-to-digital converter (ADC) into a digital signal, typically using pulse-code modulation. This digital signal can then be recorded, edited, modified, and copied using computers, audio playback machines, and other digital tools. When the sound engineer wishes to listen to the recording on headphones or loudspeakers (or when a consumer wishes to listen to a digital sound file), a digital-to-analog converter (DAC) performs the reverse process, converting a digital signal back into an analog signal, which is then sent through an audio power amplifier and ultimately to a loudspeaker.

Digital audio systems may include compression, storage, processing, and transmission components. Conversion to a digital format allows convenient manipulation, storage, transmission, and retrieval of an audio signal. Unlike analog audio, in which making copies of a recording results in generation loss and degradation of signal quality, digital audio allows an infinite number of copies to be made without any degradation of signal quality.

Digital audio workstation

A digital audio workstation (DAW) is an electronic device or application software used for recording, editing and producing audio files. DAWs come in a wide variety of configurations from a single software program on a laptop, to an integrated stand-alone unit, all the way to a highly complex configuration of numerous components controlled by a central computer. Regardless of configuration, modern DAWs have a central interface that allows the user to alter and mix multiple recordings and tracks into a final produced piece.DAWs are used for the production and recording of music, songs, speech, radio, television, soundtracks, podcasts, sound effects and nearly any other situation where complex recorded audio is needed.

Double-system recording

Double-system recording is a form of sound recording used in motion picture production whereby the sound for a scene is recorded on a machine that is separate from the camera or picture-recording apparatus.

Double-system recording is the standard procedure on motion pictures that are originally photographed on film. Recording sound-on-film directly at the time of photography has several technical limitations, and no professional motion picture camera supports this option, so all production sound is recorded on a separate recorder. This procedure requires that both camera and sound recorder share a very accurate time reference, and that the speed of the camera and sound recorders be carefully governed. Originally this was done with an electro-mechanical interlock between the camera and recorder, necessitating a physical link, a cable, between recorder and camera. As quartz-based timers came into common use, film cameras and sound recorders adopted these, and these were accurate enough to remove the need for an interlock cable.

Double-system recording requires that sound and picture be manually synchronized at the start of every "take" or camera run. This task was performed by the clapper slate. A clap sound on the recording is matched to the closed clapper image on the printed film, and thus the two recordings can be realigned into sync.

Before magnetic recording, a double-system sound recorder was either a sound camera or a phonograph lathe. Once magnetic recording became viable, a succession of magnetic sound recorders, culminating in the Nagra, were the standard. As of 2007, most double-system production sound is recorded with hard disk drive-based digital recorders, with a DAT backup.

When the apparatus recording sound and image are the same, as in a video tape recorder, sound is recorded directly onto the picture medium, and this procedure is called 'single-system recording'. On feature films that are photographed on high-definition video, audio is often recorded on the video recorder and also on secondary recorder.

Exciter (effect)

An exciter (also called a harmonic exciter or aural exciter) is an audio signal processing technique used to enhance a signal by dynamic equalization, phase manipulation, harmonic synthesis of (usually) high frequency signals, and through the addition of subtle harmonic distortion. Dynamic equalization involves variation of the equalizer characteristics in the time domain as a function of the input. Due to the varying nature, noise is reduced compared to static equalizers. Harmonic synthesis involves the creation of higher order harmonics from the fundamental frequency signals present in the recording. As noise is usually more prevalent at higher frequencies, the harmonics are derived from a purer frequency band resulting in clearer highs. Exciters are also used to synthesize harmonics of low frequency signals to simulate deep bass in smaller speakers.

Originally made in valve (tube) based equipment, they are now implemented as part of a digital signal processor, often trying to emulate analogue Exciters. Exciters are mostly found as plug-ins for sound editing software and in sound enhancement processors.

Goji Electronics

Goji Electronics, Inc. is a producer of computer, smartphone, audio products and equipment headquartered in Hemel Hempstead, United Kingdom. The audio division of the company was founded by grime artist and entrepreneur Tinchy Stryder and DSG International plc president Lord Kalms, and primarily produces products under the brand Goji Tinchy Stryder.

Since the inception of Goji, its products have been distributed by Dixons Carphone plc and its predecessor DSG International plc. The collaboration between Dixons and Kwasi Danquah III leads to an expansion of Goji Electronics into the headphones and audio equipment market.Stryder, Lord Kalms and Dixons Carphone plc all own shares in Goji.

Hard disk recorder

A hard disk recorder (HDR) is a system that uses a high-capacity hard disk to record digital audio or digital video. Hard disk recording systems represent an alternative to reel-to-reel audio tape recording and video tape recorders, and provide editing capabilities unavailable to tape recorders. Audio HDR systems, which can be standalone or computer-based, typically include provisions for digital mixing and processing of the audio signal.

Direct-to-disk recording (DDR) refers to methods which may also use optical disc recording technologies such as DVD, and Compact disc.

Magnetic tape

Magnetic tape is a medium for magnetic recording, made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders respectively. A device that stores computer data on magnetic tape is known as a tape drive.

Magnetic tape revolutionized sound recording and reproduction and broadcasting. It allowed radio, which had always been broadcast live, to be recorded for later or repeated airing. It allowed gramophone records to be recorded in multiple parts, which were then mixed and edited with tolerable loss in quality. It was a key technology in early computer development, allowing unparalleled amounts of data to be mechanically created, stored for long periods, and rapidly accessed.

In recent decades, other technologies have been developed that can perform the functions of magnetic tape. In many cases, these technologies have replaced tape. Despite this, innovation in the technology continues, and Sony and IBM continue to produce new magnetic tape drives.Over time, magnetic tape made in the 1970s and 1980s can suffer from a type of deterioration called sticky-shed syndrome. It is caused by hydrolysis of the binder in the tape and can render the tape unusable.

Microphone preamplifier

The term microphone preamplifier can either refer to the electronic circuitry within a microphone, or to a separate device or circuit that the microphone is connected to. In either instance, the purpose of the microphone preamplifier is the same.

A microphone preamplifier is a sound engineering device that prepares a microphone signal to be processed by other equipment. Microphone signals are often too weak to be transmitted to units such as mixing consoles and recording devices with adequate quality. Preamplifiers increase a microphone signal to line level (i.e. the level of signal strength required by such devices) by providing stable gain while preventing induced noise that would otherwise distort the signal. For additional discussion of signal level, see Gain stage.

A microphone preamplifier is colloquially called a microphone preamp, mic preamp, preamp (not to be confused with a control amplifier in high-fidelity reproduction equipment), mic pre and pre.

Mix automation

Modern digital audio consoles or mixers use automation. Automation allows the console to remember the audio engineer's adjustment of faders during the post-production editing process. A timecode is necessary for synchronization of automation.

Octophonic sound

Octophonic sound is a form of audio reproduction that presents eight discrete audio channels using eight speakers. For playback, the speakers may be positioned in a circle around the listeners or in any other configuration.

Typical speaker configurations are eight spaced on a circle by 45° (oriented with first speaker 0° or at 22.5°), or the vertices of a cube to create a double quadraphonic set-up with elevation (Collins 2010, 60). In reference to his own work, Karlheinz Stockhausen made a distinction between these two forms, reserving the term "octophonic" for a cube configuration, as found in his Oktophonie and the electronic music for scene 2 and the Farewell of Mittwoch aus Licht, and using the expression "eight-channel sound" for the circular arrangement, as used in Sirius, Unsichtbare Chöre, or Hours 13 to 21 of the Klang cycle (Stockhausen 1993, 150; Stockhausen 2000, 60). While quadraphonic sound uses four speakers positioned in a square at the four corners of the listening space (either on the ground or raised above the listeners), this cubical kind of octophonic spatialization offers both horizontal and vertical sound spatialization, meaning listeners get a sense of height. In order for such movement in space to be heard, it is necessary that rhythms be slow, and pitches change mainly in small steps or in glissandos (Stockhausen 1993, 151, 163).

Some notable composers who have worked with octophonic spatialisation include Karlheinz Stockhausen, Jonathan Harvey, Gérard Pape, and Larry Austin. The first known octophonic (that is, eight-channel) electronic music was John Cage's Williams Mix (1951–53) for eight separate simultaneously played back quarter-inch magnetic tapes (Collins 2010, 26; Leider 2004, 290). Austin later made a surround-sound octophonic mix of Williams Mix, Williams (re)Mix[ed] (1997–2000), using the score and different sound sources (Austin 2004, 189). This version is intended to be played back on eight speakers surrounding the audience in a 360° circle, using (unlike Cage's original version) stereo source recordings heard in adjacent speaker pairs (Austin 2004, 205, 207). Octophonic sound (in the general sense of eight-channel playback) was stimulated primarily by "the equal coverage it provides to all listening angles" and also by the precedence of eight-channel (initially tape) sound and subsequent ease of playback (Leider 2004, 290).

Pitch correction

Pitch correction is an electronic effects unit or audio software that changes the intonation (highness or lowness in pitch) of an audio signal so that all pitches will be notes from the equally tempered system (i.e., like the pitches on a piano). Pitch correction devices do this without affecting other aspects of its sound. Pitch correction first detects the pitch of an audio signal (using a live pitch detection algorithm), then calculates the desired change and modifies the audio signal accordingly. The widest use of pitch corrector devices is in Western popular music on vocal lines.

Pitch shift

Pitch shifting is a sound recording technique in which the original pitch of a sound is raised or lowered. Effects units that raise or lower pitch by a pre-designated musical interval (transposition) are called pitch shifters or pitch benders.


A preamplifier (preamp or "pre") is an electronic amplifier that converts a weak electrical signal into an output signal strong enough to be noise-tolerant and strong enough for further processing, or for sending to a power amplifier and a loudspeaker. Without this, the final signal would be noisy or distorted. They are typically used to amplify signals from analog sensors such as microphones and pickups. Because of this, the preamplifier is often placed close to the sensor to reduce the effects of noise and interference.

Shepard tone

A Shepard tone, named after Roger Shepard, is a sound consisting of a superposition of sine waves separated by octaves. When played with the bass pitch of the tone moving upward or downward, it is referred to as the Shepard scale. This creates the auditory illusion of a tone that continually ascends or descends in pitch, yet which ultimately seems to get no higher or lower.


Sondor is a manufacturer of Audio Video equipment located in Zollikon, Switzerland until 2017.

Sondor was founded in 1952 by Willy Hungerbuehler. Sondor started as a manufacturer of 16 mm film and 35 mm film magnetic film equipment. They are noted as inventing the standard for bi-phase interlocking pulse signals to sync sound to film. Sondor added a film transport telecine to it line of film sound equipment. Sondor products are found in many in post-production studios for record and playback and in movie theater for sound playback. playback.

Sondor film transport telecines uses a spinning prism telecine, like the model NOVA and ALTRA.

Some Sound Film followers player-recorder are the: OMA E and BASIC.

SOUNDHOUSE is a product to add sound pick up to other telecines, like the Spirit DataCine.

The other major maker of sound followers is Magna Tech.

DAT recorders and Direct to disk recording have replaced much of the work done on separate film sound followers.

On December 9, 2016 Digital Film Technology (dft), completed the acquisition of Sondor. DFT is the maker of the Scanity film scanner. Current Sondor products:

Versa, telecine-scanner, optical sound scan: and Magnetic sound scan

Resonances, optical soundtrack

Tape recorder

An audio tape recorder, tape deck, or tape machine is a sound recording and reproduction device that records and plays back sounds usually using magnetic tape for storage. In its present-day form, it records a fluctuating signal by moving the tape across a tape head that polarizes the magnetic domains in the tape in proportion to the audio signal. Tape-recording devices include the reel-to-reel tape deck and the cassette deck, which uses a cassette for storage.

The use of magnetic tape for sound recording originated around 1930 in Germany as paper tape with oxide lacquered to it. Prior to the development of magnetic tape, magnetic wire recorders had successfully demonstrated the concept of magnetic recording, but they never offered audio quality comparable to the other recording and broadcast standards of the time. This German invention was the start of a long string of innovations that have led to present day magnetic tape recordings.

Magnetic tape revolutionized both the radio broadcast and music recording industries. It gave artists and producers the power to record and re-record audio with minimal loss in quality as well as edit and rearrange recordings with ease. The alternative recording technologies of the era, transcription discs and wire recorders, could not provide anywhere near this level of quality and functionality.

Since some early refinements improved the fidelity of the reproduced sound, magnetic tape has been the highest quality analog recording medium available. As of the first decade of the 21st century, analog magnetic tape has been largely replaced by digital recording technologies.

Vehicle audio

Vehicle audio is equipment installed in a car or other vehicle to provide in-car entertainment and information for the vehicle occupants. Until the 1950s it consisted of a simple AM radio. Additions since then have included FM radio (1952), 8-Track tape players, Cassette Players, CD players (1984), DVD players, Blu-ray players, navigation systems, Bluetooth telephone integration, and smartphone controllers like CarPlay and Android Auto. Once controlled from the dashboard with a few buttons, they can now be controlled by steering wheel controls and voice commands.

Initially implemented for listening to music and radio, vehicle audio is now part of car telematics, telecommunication, in-vehicle security, handsfree calling, navigation, and remote diagnostics systems. It is also used to create fake engine noise. For the 2015 Ford Mustang EcoBoost, an "Active Noise Control" system was developed that amplifies the engine sound through the car speakers. A similar system is used in the F-150 pickup truck. Volkswagen uses a Soundaktor, a special speaker to play sounds in cars such as the Golf GTi and Beetle Turbo. BMW plays a recorded sample of its motors through the car speakers, using a different samples according to the engine’s load and power.

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