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136-403: Stereophonic sound , or more commonly stereo , is a method of sound reproduction that recreates a multi-directional, 3-dimensional audible perspective. This is usually achieved by using two independent audio channels through a configuration of two loudspeakers (or stereo headphones ) in such a way as to create the impression of sound heard from various directions, as in natural hearing. Because

272-428: A binaural record out of it. This consisted of two separate channels cut into two separate groups of grooves running next to each other, one running from the edge of the disc to halfway through and the other starting at the halfway point and ending up towards the label. He used two lateral grooves with a 500 Hz crossover in the inner track to try and compensate for the lower fidelity and high-frequency distortion on

408-408: A crossover network ). The speaker driver is an electroacoustic transducer that converts an electrical audio signal into a corresponding sound . The driver can be viewed as a linear motor attached to a diaphragm which couples that motor's movement to motion of air, that is, sound. An audio signal, typically from a microphone, recording, or radio broadcast, is amplified electronically to

544-435: A whizzer : a small, light cone attached to the joint between the voice coil and the primary cone. The whizzer cone extends the high-frequency response of the driver and broadens its high-frequency directivity, which would otherwise be greatly narrowed due to the outer diameter cone material failing to keep up with the central voice coil at higher frequencies. The main cone in a whizzer design is manufactured so as to flex more in

680-402: A combination of one or more resistors , inductors and capacitors . These components are combined to form a filter network and are most often placed between the full frequency-range power amplifier and the loudspeaker drivers to divide the amplifier's signal into the necessary frequency bands before being delivered to the individual drivers. Passive crossover circuits need no external power beyond

816-808: A complete loudspeaker system to provide performance beyond that constraint. The three most commonly used sound radiation systems are the cone, dome and horn-type drivers. A full- or wide-range driver is a speaker driver designed to be used alone to reproduce an audio channel without the help of other drivers and therefore must cover the audio frequency range required by the application. These drivers are small, typically 3 to 8 inches (7.6 to 20.3 cm) in diameter to permit reasonable high-frequency response, and carefully designed to give low-distortion output at low frequencies, though with reduced maximum output level. Full-range drivers are found, for instance, in public address systems, in televisions, small radios, intercoms, and some computer speakers . In hi-fi speaker systems,

952-426: A crossover knob and a phase switch). These variants are known as active or powered subwoofers. In contrast, passive subwoofers require external amplification. In typical installations, subwoofers are physically separated from the rest of the speaker cabinets. Because of propagation delay and positioning, their output may be out of phase with the rest of the sound. Consequently, a subwoofer's power amp often has

1088-401: A decade, and broadcasters were looking for better materials from which to make phonograph records as well as a better format in which to record them to play over the narrow and thus inherently noisy radio channel. As radio had been playing the same shellac discs available to the public, it was found that, even though the playback system was now electric rather than acoustic, the surface noise on

1224-426: A driver; each implementation has advantages and disadvantages. Polyester foam, for example, is lightweight and economical, though usually leaks air to some degree and is degraded by time, exposure to ozone, UV light, humidity and elevated temperatures, limiting useful life before failure. The wire in a voice coil is usually made of copper , though aluminum —and, rarely, silver —may be used. The advantage of aluminum

1360-421: A dual role, acting also as a choke coil , filtering the power supply of the amplifier that the loudspeaker was connected to. AC ripple in the current was attenuated by the action of passing through the choke coil. However, AC line frequencies tended to modulate the audio signal going to the voice coil and added to the audible hum. In 1930 Jensen introduced the first commercial fixed-magnet loudspeaker; however,

1496-406: A dynamic loudspeaker, uses a lightweight diaphragm , or cone , connected to a rigid basket , or frame , via a flexible suspension, commonly called a spider , that constrains a voice coil to move axially through a cylindrical magnetic gap. A protective dust cap glued in the cone's center prevents dust, most importantly ferromagnetic debris, from entering the gap. When an electrical signal

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1632-483: A female character in the novel Massarenes (1897) as "A modern woman of the world. As costly as an ironclad and as complicated as theatrophone." In 1890, the system became operational as a service under the name "théâtrophone" in Paris. The service was offered by Compagnie du Théâtrophone (The Théâtrophone Company), which was founded by MM. Marinovitch and Szarvady. The théâtrophone offered theatre and opera performances to

1768-458: A high-frequency horn that sent sound through a hole in the pole piece of a 15-inch woofer for near-point-source performance. Altec's "Voice of the Theatre" loudspeaker system was first sold in 1945, offering better coherence and clarity at the high output levels necessary in movie theaters. The Academy of Motion Picture Arts and Sciences immediately began testing its sonic characteristics; they made it

1904-465: A hill-and-dale (vertically modulated) format on his cylinders and discs since 1877, and Berliner had been recording in a side-to-side (lateral) format since shortly thereafter. Each format developed on its own trajectory until the late 1920s when electric recording on disc, utilizing a microphone, surpassed acoustic recording which required a loud performance into what amounted to a megaphone in reverse. At that time, AM radio had been around for roughly

2040-405: A larger magnet for equivalent performance. Electromagnets were often used in musical instrument amplifiers cabinets well into the 1950s; there were economic savings in those using tube amplifiers as the field coil could, and usually did, do double duty as a power supply choke. Very few manufacturers still produce electrodynamic loudspeakers with electrically powered field coils , as was common in

2176-439: A monophonic system since a stereo system contains two preamplifiers, two amplifiers, and two speaker systems. In addition, the user would need an FM stereo tuner, to upgrade any tape recorder to a stereo model, and to have their phonograph fitted with a stereo cartridge. In the early days, it was not clear whether consumers would think the sound was so much better as to be worth twice the price. Thomas Edison had been recording in

2312-447: A more modern 24 fps system with brand-new 65 mm self-blimped production cameras ( Mitchell BFC ... "Blimped Fox Camera") and brand-new 65 mm MOS cameras (Mitchell FC ... "Fox Camera") and brand-new Super Baltar lenses in a wide variety of focal lengths, first employed on South Pacific . Essentially, although Todd-AO was also available to others, the format became Fox's premier origination and presentation apparatus, replacing

2448-419: A phase-delay adjustment which may be used improve performance of the system as a whole. Subwoofers are widely used in large concert and mid-sized venue sound reinforcement systems. Subwoofer cabinets are often built with a bass reflex port, a design feature which if properly engineered improves bass performance and increases efficiency. A woofer is a driver that reproduces low frequencies. The driver works with

2584-412: A power level capable of driving that motor in order to reproduce the sound corresponding to the original unamplified electronic signal. This is thus the opposite function to the microphone ; indeed the dynamic speaker driver, by far the most common type, is a linear motor in the same basic configuration as the dynamic microphone which uses such a motor in reverse, as a generator . The dynamic speaker

2720-414: A separate box, necessary to accommodate the size of the components used. Passive crossovers may be simple for low-order filtering, or complex to allow steep slopes such as 18 or 24 dB per octave. Passive crossovers can also be designed to compensate for undesired characteristics of driver, horn, or enclosure resonances, and can be tricky to implement, due to component interaction. Passive crossovers, like

2856-552: A separate listening room. Several stereophonic test recordings, using two microphones connected to two styli cutting two separate grooves on the same wax disc, were made with Leopold Stokowski and the Philadelphia Orchestra at Philadelphia's Academy of Music in March 1932. The first (made on March 12, 1932), of Scriabin's Prometheus: Poem of Fire , is the earliest known surviving intentional stereo recording. The performance

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2992-581: A series of telephone transmitters connected from the stage of the Paris Opera to a suite of rooms at the Paris Electrical Exhibition, where listeners could hear a live transmission of performances through receivers for each ear. Scientific American reported: Every one who has been fortunate enough to hear the telephones at the Palais de l'Industrie has remarked that, in listening with both ears at

3128-483: A single driver enclosed in a suitable enclosure. Since sound in this frequency range can easily bend around corners by diffraction , the speaker aperture does not have to face the audience, and subwoofers can be mounted in the bottom of the enclosure, facing the floor. This is eased by the limitations of human hearing at low frequencies; Such sounds cannot be located in space, due to their large wavelengths compared to higher frequencies which produce differential effects in

3264-408: A single piece, called the poleplate or yoke. The size and type of magnet and details of the magnetic circuit differ, depending on design goals. For instance, the shape of the pole piece affects the magnetic interaction between the voice coil and the magnetic field, and is sometimes used to modify a driver's behavior. A shorting ring , or Faraday loop , may be included as a thin copper cap fitted over

3400-513: A somewhat artificial six-track panning method. A process known somewhat derogatorily as the Columbia Spread was often used to synthesize Left Center and Right Center from a combination of Left and Center and Right and Center, respectively, or, for effects, the effect could be "panned" anywhere across the five stage speakers using a one-in/five-out pan pot. Dolby, who did not approve of this practice, which results in loss of separation, instead used

3536-411: A system using compressed air as an amplifying mechanism for his early cylinder phonographs, but he ultimately settled for the familiar metal horn driven by a membrane attached to the stylus. In 1898, Horace Short patented a design for a loudspeaker driven by compressed air; he then sold the rights to Charles Parsons , who was issued several additional British patents before 1910. A few companies, including

3672-441: A time before intentional stereophonic recording technology existed. Modern stereophonic technology was invented in the 1930s by British engineer Alan Blumlein at EMI , who patented stereo records, stereo films, and also surround sound. In early 1931, Blumlein and his wife were at a local cinema. The sound reproduction systems of the early talkies invariably only had a single set of speakers – which could lead to

3808-561: A vast array of sounds, ranging from railroad sounds to thunderstorms. By 1953, Cook had a catalog of about 25 stereo records for sale to audiophiles . The first stereo recordings using magnetic tape were made in Germany in the early 1940s using Magnetophon recorders. Around 300 recordings were made of various symphonies, most of which were seized by the Red Army at the end of World War II. The recordings were of relatively high fidelity , thanks to

3944-563: A vertical fashion to minimize rumble. The overhead in this scheme limited the playing time to slightly longer than a single even at 33 + 1 ⁄ 3 RPM on a 12-inch disc. Another failed experiment in the late 1920s and early '30s involved recording the left channel on one side of the disc and recording the right channel on the other side of the disc. These were manufactured on twin film-company recording lathes which ran in perfect sync with one another, and were capable of counter-clockwise as well as conventional clockwise recording. Each master

4080-445: A wide range of frequencies with even coverage, most loudspeaker systems employ more than one driver, particularly for higher sound pressure level (SPL) or maximum accuracy. Individual drivers are used to reproduce different frequency ranges. The drivers are named subwoofers (for very low frequencies); woofers (low frequencies); mid-range speakers (middle frequencies); tweeters (high frequencies); and sometimes supertweeters , for

4216-469: Is Cinerama was still playing only in New York City, most moviegoing audiences heard stereophonic sound for the first time with House of Wax , an early 3-D film starring Vincent Price and produced by Warner Bros. Unlike the 4-track mag release-print stereo films of the period which featured four thin strips of magnetic material running down the length of the film, inside and outside the sprocket holes,

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4352-475: Is a low priority. A subwoofer is a woofer driver used only for the lowest-pitched part of the audio spectrum: typically below 200 Hz for consumer systems, below 100 Hz for professional live sound, and below 80 Hz in THX -approved systems. Because the intended range of frequencies is limited, subwoofer system design is usually simpler in many respects than for conventional loudspeakers, often consisting of

4488-985: Is a small amount of passive electronics called a crossover network which helps direct components of the electronic signal to the speaker drivers best capable of reproducing those frequencies. In a so-called powered speaker system, the power amplifier actually feeding the speaker drivers is built into the enclosure itself; these have become more and more common especially as computer speakers. Smaller speakers are found in devices such as radios , televisions , portable audio players , personal computers ( computer speakers ), headphones , and earphones . Larger, louder speaker systems are used for home hi-fi systems ( stereos ), electronic musical instruments , sound reinforcement in theaters and concert halls, and in public address systems . The term loudspeaker may refer to individual transducers (also known as drivers ) or to complete speaker systems consisting of an enclosure and one or more drivers. To adequately and accurately reproduce

4624-416: Is applied to the voice coil, a magnetic field is created by the electric current in the voice coil, making it a variable electromagnet. The coil and the driver's magnetic system interact in a manner similar to a solenoid , generating a mechanical force that moves the coil (and thus, the attached cone). Application of alternating current moves the cone back and forth, accelerating and reproducing sound under

4760-551: Is designed to be rigid, preventing deformation that could change critical alignments with the magnet gap, perhaps allowing the voice coil to rub against the magnet around the gap. Chassis are typically cast from aluminum alloy, in heavier magnet-structure speakers; or stamped from thin sheet steel in lighter-structure drivers. Other materials such as molded plastic and damped plastic compound baskets are becoming common, especially for inexpensive, low-mass drivers. A metallic chassis can play an important role in conducting heat away from

4896-404: Is its light weight, which reduces the moving mass compared to copper. This raises the resonant frequency of the speaker and increases its efficiency. A disadvantage of aluminum is that it is not easily soldered, and so connections must be robustly crimped together and sealed. Voice-coil wire cross sections can be circular, rectangular, or hexagonal, giving varying amounts of wire volume coverage in

5032-424: Is then reproduced over multiple loudspeakers to recreate, as closely as possible, the live sound. Secondly artificial or pan stereo, in which a single-channel ( mono ) sound is reproduced over multiple loudspeakers. By varying the relative amplitude of the signal sent to each speaker, an artificial direction (relative to the listener) can be suggested. The control which is used to vary this relative amplitude of

5168-437: Is usually conically shaped for sturdiness) in contact with air, thus creating sound waves . In addition to dynamic speakers, several other technologies are possible for creating sound from an electrical signal, a few of which are in commercial use. In order for a speaker to efficiently produce sound, especially at lower frequencies, the speaker driver must be baffled so that the sound emanating from its rear does not cancel out

5304-484: Is well damped to reduce vibrations continuing after the signal has stopped with little or no audible ringing due to its resonance frequency as determined by its usage. In practice, all three of these criteria cannot be met simultaneously using existing materials; thus, driver design involves trade-offs . For example, paper is light and typically well-damped, but is not stiff; metal may be stiff and light, but it usually has poor damping; plastic can be light, but typically,

5440-611: The Chicago World's Fair in 1933 using a dummy with microphones instead of ears . The two signals were sent out over separate AM station bands. Utilizing selections recorded by the Philadelphia Orchestra , under the direction of Leopold Stokowski , intended for but not used in Walt Disney's Fantasia , the Carnegie Hall demonstration by Bell Laboratories on April 9 and 10, 1940, used three huge speaker systems. Synchronization

5576-446: The Greek στερεός ( stereós , "firm, solid") + φωνή ( phōnḗ , "sound, tone, voice") and it was coined in 1927 by Western Electric , by analogy with the word stereoscopic . Stereo sound systems can be divided into two forms: the first is true or natural stereo in which a live sound is captured, with any natural reverberation present, by an array of microphones . The signal

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5712-607: The Théâtrophone , and in England from 1895 to 1925 as the Electrophone . Both were services available by coin-operated receivers at hotels and cafés, or by subscription to private homes. There have been cases in which two recording lathes (for the sake of producing two simultaneous masters) were fed from two separate microphones; when both masters survive, modern engineers have been able to synchronize them to produce stereo recordings from

5848-514: The Victor Talking Machine Company and Pathé , produced record players using compressed-air loudspeakers. Compressed-air designs are significantly limited by their poor sound quality and their inability to reproduce sound at low volume. Variants of the design were used for public address applications, and more recently, other variations have been used to test space-equipment resistance to the very loud sound and vibration levels that

5984-506: The audible frequency range. The smaller drivers capable of reproducing the highest audio frequencies are called tweeters , those for middle frequencies are called mid-range drivers and those for low frequencies are called woofers . Sometimes the reproduction of the very lowest frequencies (20–~50  Hz ) is augmented by a so-called subwoofer often in its own (large) enclosure. In a two-way or three-way speaker system (one with drivers covering two or three different frequency ranges) there

6120-631: The film house industry standard in 1955. In 1954, Edgar Villchur developed the acoustic suspension principle of loudspeaker design. This allowed for better bass response than previously obtainable from drivers mounted in larger cabinets. He and his partner Henry Kloss formed the Acoustic Research company to manufacture and market speaker systems using this principle. Subsequently, continuous developments in enclosure design and materials led to significant audible improvements. The most notable improvements to date in modern dynamic drivers, and

6256-418: The mid frequencies (between the woofer and tweeter). Mid-range driver diaphragms can be made of paper or composite materials and can be direct radiation drivers (rather like smaller woofers) or they can be compression drivers (rather like some tweeter designs). If the mid-range driver is a direct radiator, it can be mounted on the front baffle of a loudspeaker enclosure, or, if a compression driver, mounted at

6392-528: The spider , which connects the diaphragm or voice coil to the lower frame and provides the majority of the restoring force, and the surround , which helps center the coil/cone assembly and allows free pistonic motion aligned with the magnetic gap. The spider is usually made of a corrugated fabric disk, impregnated with a stiffening resin. The name comes from the shape of early suspensions, which were two concentric rings of Bakelite material, joined by six or eight curved legs . Variations of this topology included

6528-420: The (intended) sound from the front; this generally takes the form of a speaker enclosure or speaker cabinet , an often rectangular box made of wood, but sometimes metal or plastic. The enclosure's design plays an important acoustic role thus determining the resulting sound quality. Most high fidelity speaker systems (picture at right) include two or more sorts of speaker drivers, each specialized in one part of

6664-513: The 3-D production of The Charge at Feather River , and Island in the Sky . Unfortunately, as of 2012, the stereo magnetic tracks to both these films are considered lost forever. In addition, a large percentage of 3-D films carried variations on three-track magnetic sound: It Came from Outer Space ; I, the Jury ; The Stranger Wore a Gun ; Inferno ; Kiss Me, Kate ; and many others. Inspired by Cinerama ,

6800-410: The 70 mm prints would be mixed for stereo, while the 35 mm reduction prints would be remixed for mono. Some films shot in 35 mm, such as Camelot , featured four-track stereophonic sound and were then blown up to 70 mm so that they could be shown on a giant screen with six-track stereophonic sound. Unfortunately however, many of these presentations were only pseudo stereo, utilizing

6936-550: The CinemaScope 55 mm system. Current DVDs of the two CinemaScope feature titles were transferred from the original 55 mm negatives, often including the separate 35 mm films as extras for comparison. Beginning in 1957, films recorded in stereo (except for those shown in Cinerama or Todd-AO) carried an alternate mono track for theatres not ready or willing to re-equip for stereo. From then until about 1975, when Dolby Stereo

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7072-862: The King Luís I of Portugal decided to use the system, when he could not attend an opera in person. The director of the Edison Gower Bell Company, who was responsible for this théâtrophone installation, was later awarded the Military Order of Christ . The théâtrophone technology was made available in Belgium in 1884, and in Lisbon in 1885. In Sweden, the first telephone transmission of an opera performance took place in Stockholm in May 1887. The British writer Ouida describes

7208-632: The King of Siam , The Day the Earth Stood Still and Sun Valley Serenade which, along with Orchestra Wives , feature the only stereophonic recordings of the Glenn Miller Orchestra as it was during its heyday of the Swing Era . Walt Disney began experimenting with multichannel sound in the early 1930s as noted above. The first commercial motion picture to be exhibited with stereophonic sound

7344-411: The addition of a felt disc to provide a barrier to particles that might otherwise cause the voice coil to rub. The cone surround can be rubber or polyester foam , treated paper or a ring of corrugated, resin-coated fabric; it is attached to both the outer cone circumference and to the upper frame. These diverse surround materials, their shape and treatment can dramatically affect the acoustic output of

7480-542: The appropriate driver. A loudspeaker system with n separate frequency bands is described as n-way speakers : a two-way system will have a woofer and a tweeter; a three-way system employs a woofer, a mid-range, and a tweeter. Loudspeaker drivers of the type pictured are termed dynamic (short for electrodynamic) to distinguish them from other sorts including moving iron speakers , and speakers using piezoelectric or electrostatic systems. Johann Philipp Reis installed an electric loudspeaker in his telephone in 1861; it

7616-457: The artistic adjustment of overall volume and the relative volume of each track in relation to the others. Stokowski, who was always interested in sound reproduction technology personally participated in the enhancement of the sound at the demonstration. The speakers produced sound levels of up to 100 decibels, and the demonstration held the audience "spellbound, and at times not a little terrified", according to one report. Sergei Rachmaninoff , who

7752-416: The audio signal itself, but have some disadvantages: they may require larger inductors and capacitors due to power handling requirements. Unlike active crossovers which include a built-in amplifier, passive crossovers have an inherent attenuation within the passband , typically leading to a reduction in damping factor before the voice coil. An active crossover is an electronic filter circuit that divides

7888-449: The characteristics of the speaker enclosure to produce suitable low frequencies. Some loudspeaker systems use a woofer for the lowest frequencies, sometimes well enough that a subwoofer is not needed. Additionally, some loudspeakers use the woofer to handle middle frequencies, eliminating the mid-range driver. A mid-range speaker is a loudspeaker driver that reproduces a band of frequencies generally between 1–6 kHz, otherwise known as

8024-486: The control of the applied electrical signal coming from the amplifier. The following is a description of the individual components of this type of loudspeaker. The diaphragm is usually manufactured with a cone- or dome-shaped profile. A variety of different materials may be used, but the most common are paper, plastic, and metal. The ideal material is rigid, to prevent uncontrolled cone motions, has low mass to minimize starting force requirements and energy storage issues and

8160-413: The crossover is an assembly of filters that separate the input signal into different frequency bands according to the requirements of each driver. Hence the drivers receive power only in the sound frequency range they were designed for, thereby reducing distortion in the drivers and interference between them. Crossovers can be passive or active . A passive crossover is an electronic circuit that uses

8296-457: The disc would mask the music after just a few plays. The development of acetate, bakelite, and vinyl, and the production of radio broadcast transcriptions helped to solve this. Once these considerably quieter compounds were developed, it was discovered that the rubber-idler-wheel-driven turntables of the period had a great deal of low-frequency rumble – but only in the lateral plane. So, even though with all other factors being equal,

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8432-540: The discovery of AC bias . A 1944 recording of Anton Bruckner 's Symphony No. 8 directed by Herbert von Karajan and the Orchester der Berliner Staatsoper and a 1944 or 1945 recording of Walter Gieseking playing Beethoven 's Piano Concerto No. 5 (with anti-aircraft fire audible in the background) are the only recordings still known to exist. In the US, stereo magnetic tape recording was demonstrated on standard 1/4-inch tape for

8568-746: The driver units that they feed, have power handling limits, have insertion losses , and change the load seen by the amplifier. The changes are matters of concern for many in the hi-fi world. When high output levels are required, active crossovers may be preferable. Active crossovers may be simple circuits that emulate the response of a passive network or may be more complex, allowing extensive audio adjustments. Some active crossovers, usually digital loudspeaker management systems, may include electronics and controls for precise alignment of phase and time between frequency bands, equalization, dynamic range compression and limiting . Most loudspeaker systems consist of drivers mounted in an enclosure, or cabinet. The role of

8704-422: The drivers by moving one or more driver mounting locations forward or back so that the acoustic center of each driver is in the same vertical plane. This may also involve tilting the driver back, providing a separate enclosure mounting for each driver, or using electronic techniques to achieve the same effect. These attempts have resulted in some unusual cabinet designs. Th%C3%A9%C3%A2trophone The origin of

8840-487: The drivers mounted in holes in it. However, in this approach, sound frequencies with a wavelength longer than the baffle dimensions are canceled out because the antiphase radiation from the rear of the cone interferes with the radiation from the front. With an infinitely large panel, this interference could be entirely prevented. A sufficiently large sealed box can approach this behavior. Since panels of infinite dimensions are impossible, most enclosures function by containing

8976-589: The earliest designs. Speaker system design involves subjective perceptions of timbre and sound quality, measurements and experiments. Adjusting a design to improve performance is done using a combination of magnetic, acoustic, mechanical, electrical, and materials science theory, and tracked with high-precision measurements and the observations of experienced listeners. A few of the issues speaker and driver designers must confront are distortion, acoustic lobing , phase effects, off-axis response, and crossover artifacts. Designers can use an anechoic chamber to ensure

9112-501: The ears due to shadowing by the head, and diffraction around it, both of which we rely upon for localization clues. To accurately reproduce very low bass notes, subwoofer systems must be solidly constructed and properly braced to avoid unwanted sounds from cabinet vibrations. As a result, good subwoofers are typically quite heavy. Many subwoofer systems include integrated power amplifiers and electronic subsonic -filters, with additional controls relevant to low-frequency reproduction (e.g.

9248-422: The enclosure is to prevent sound waves emanating from the back of a driver from interfering destructively with those from the front. The sound waves emitted from the back are 180° out of phase with those emitted forward, so without an enclosure they typically cause cancellations which significantly degrade the level and quality of sound at low frequencies. The simplest driver mount is a flat panel ( baffle ) with

9384-429: The first film industry-standard loudspeaker system, "The Shearer Horn System for Theatres", a two-way system, was introduced by Metro-Goldwyn-Mayer . It used four 15" low-frequency drivers, a crossover network set for 375 Hz, and a single multi-cellular horn with two compression drivers providing the high frequencies. John Kenneth Hilliard , James Bullough Lansing , and Douglas Shearer all played roles in creating

9520-578: The first time in 1952, using two sets of recording and playback heads, upside-down and offset from one another. A year later, Remington Records began recording a number of its sessions in stereo, including performances by Thor Johnson and the Cincinnati Symphony Orchestra . Loudspeaker A loudspeaker (commonly referred to as a speaker or, more fully, a speaker system ) is a combination of one or more speaker drivers , an enclosure , and electrical connections (possibly including

9656-433: The highest audible frequencies and beyond. The terms for different speaker drivers differ, depending on the application. In two-way systems there is no mid-range driver, so the task of reproducing the mid-range sounds is divided between the woofer and tweeter. When multiple drivers are used in a system, a filter network, called an audio crossover , separates the incoming signal into different frequency ranges and routes them to

9792-498: The inner track. Each groove needed its own monophonic needle and cartridge on its own branch of the tonearm, and each needle was connected to a separate amplifier and speaker. This setup was intended to demonstrate Cook's cutter heads at a New York audio fair. It was not intended to promote the binaural process; but soon afterward, the demand for such recordings and the equipment to play them grew, and Cook's company, Cook Records, began to produce such records commercially. Cook recorded

9928-401: The introduction of digital cinema , Dolby Surround 7.1 and Dolby Atmos in 2010 and 2012 respectively. The progress of stereophonic sound was paced by the technical difficulties of recording and reproducing two or more channels in synchronization with one another and by the economic and marketing issues of introducing new audio media and equipment. A stereo system cost up to twice as much as

10064-419: The large, heavy iron magnets of the day were impractical and field-coil speakers remained predominant until the widespread availability of lightweight alnico magnets after World War II. In the 1930s, loudspeaker manufacturers began to combine two and three drivers or sets of drivers each optimized for a different frequency range in order to improve frequency response and increase sound pressure level. In 1937,

10200-412: The latter of which used up to four separate magnetic soundtracks. VistaVision took a simplified, low-cost approach to stereophonic sound; its Perspecta system featured only a monaural track, but through subaudible tones, it could change the direction of the sound to come from the left, right or both directions at once. Because of the standard 35 mm-size film, CinemaScope and its stereophonic sound

10336-501: The launching of rockets produces. The first experimental moving-coil (also called dynamic ) loudspeaker was invented by Oliver Lodge in 1898. The first practical moving-coil loudspeakers were manufactured by Danish engineer Peter L. Jensen and Edwin Pridham in 1915, in Napa, California . Like previous loudspeakers these used horns to amplify the sound produced by a small diaphragm. Jensen

10472-479: The left center and right center channels for LFE (low-frequency enhancement) utilizing the bass units of the otherwise redundant intermediate front speakers, and later the unused HF capacity of these channels to provide for stereo surround in place of the mono surround. Dolby Stereo was succeeded by Dolby Digital 5.1 in the cinema, which retained the Dolby Stereo 70 mm 5.1 channel layout, and more recently with

10608-400: The left channel was recorded laterally and the right channel was recorded vertically, still utilizing a standard 3-mil 78-RPM groove, over three times larger than the modern LP stylus of the late 20th Century. In this system all the low-frequency rumble was in the left channel and all the high-frequency distortion was in the right channel. Over a quarter of a century later, it was decided to tilt

10744-415: The loudspeaker diaphragm—again resulting in degradation of sound quality. This can be reduced by internal absorption using absorptive materials such as glass wool , wool, or synthetic fiber batting, within the enclosure. The internal shape of the enclosure can also be designed to reduce this by reflecting sounds away from the loudspeaker diaphragm, where they may then be absorbed. Other enclosure types alter

10880-454: The loudspeakers that employ them, are improvements in cone materials, the introduction of higher-temperature adhesives, improved permanent magnet materials, improved measurement techniques, computer-aided design , and finite element analysis. At low frequencies, Thiele/Small parameters electrical network theory has been used to optimize bass driver and enclosure synergy since the early 1970s. The most common type of driver, commonly called

11016-420: The magnetic gap space. The coil is oriented co-axially inside the gap; it moves back and forth within a small circular volume (a hole, slot, or groove) in the magnetic structure. The gap establishes a concentrated magnetic field between the two poles of a permanent magnet; the outside ring of the gap is one pole, and the center post (called the pole piece) is the other. The pole piece and backplate are often made as

11152-451: The minimum number of amplifier channels. Some loudspeaker designs use a combination of passive and active crossover filtering, such as a passive crossover between the mid- and high-frequency drivers and an active crossover for the low-frequency driver. Passive crossovers are commonly installed inside speaker boxes and are by far the most common type of crossover for home and low-power use. In car audio systems, passive crossovers may be in

11288-561: The movie industry moved quickly to create simpler and cheaper widescreen systems, the first of which, Todd-AO , was developed by Broadway promoter Michael Todd with financial backing from Rodgers and Hammerstein, to use a single 70 mm film running at 30 frames per second with 6 magnetic soundtracks, for their screen presentation of Oklahoma! . Major Hollywood studios immediately rushed to create their own unique formats, such as MGM 's Camera 65 , Paramount Pictures ' VistaVision and Twentieth Century-Fox Film Corporation 's CinemaScope ,

11424-480: The movies in 1927, the speed of radio program transcriptions was reduced to match, once again to inhibit playback of the discs on normal home consumer equipment. Even though the stylus size remained the same as consumer records at either 3 mils (76 μm) or 2.7 mils (69 μm), the disc size was increased from 12 inches (30 cm) to the same 16 inches (41 cm) as those used in early talking pictures in order to create further incompatibility. Now, not only could

11560-463: The multi-dimensional perspective is the crucial aspect, the term stereophonic also applies to systems with more than two channels or speakers such as quadraphonic and surround sound . Binaural sound systems are also stereophonic . Stereo sound has been in common use since the 1970s in entertainment media such as broadcast radio, recorded music, television, video cameras , cinema, computer audio, and internet. The word stereophonic derives from

11696-596: The orchestra's conductor, was present in Constitution Hall to control the sound mix. Five years later, the same system would be expanded onto multichannel film recording and used from the concert hall in Philadelphia to the recording labs at Bell Labs in New Jersey in order to record Walt Disney 's Fantasia (1940) in what Disney called Fantasound . Later that same year, Bell Labs also demonstrated binaural sound, at

11832-423: The other three. The film was not initially a financial success, however, after two months of road-show exhibition in selected cities, its soundtrack was remixed into mono sound for general release. It was not until its 1956 re-release that stereo sound was restored to the film. A Cinerama demonstration film by Lowell Thomas and Mike Todd titled This is Cinerama was released on September 30, 1952. The format

11968-617: The outer diameter than in the center. The result is that the main cone delivers low frequencies and the whizzer cone contributes most of the higher frequencies. Since the whizzer cone is smaller than the main diaphragm, output dispersion at high frequencies is improved relative to an equivalent single larger diaphragm. Limited-range drivers, also used alone, are typically found in computers, toys, and clock radios . These drivers are less elaborate and less expensive than wide-range drivers, and they may be severely compromised to fit into very small mounting locations. In these applications, sound quality

12104-487: The output power of some designs has been increased to levels useful for professional sound reinforcement, and their output pattern is wide in the horizontal plane, a pattern that has convenient applications in concert sound. A coaxial driver is a loudspeaker driver with two or more combined concentric drivers. Coaxial drivers have been produced by Altec , Tannoy , Pioneer , KEF , SEAS, B&C Speakers, BMS, Cabasse and Genelec . Used in multi-driver speaker systems ,

12240-429: The patent by Rice and Kellogg is the adjustment of mechanical parameters to provide a reasonably flat frequency response . These first loudspeakers used electromagnets , because large, powerful permanent magnets were generally not available at a reasonable price. The coil of an electromagnet, called a field coil, was energized by a current through a second pair of connections to the driver. This winding usually served

12376-453: The pole tip or as a heavy ring situated within the magnet-pole cavity. The benefits of this complication is reduced impedance at high frequencies, providing extended treble output, reduced harmonic distortion, and a reduction in the inductance modulation that typically accompanies large voice coil excursions. On the other hand, the copper cap requires a wider voice-coil gap, with increased magnetic reluctance; this reduces available flux, requiring

12512-540: The process, Carousel and The King and I , were released in 35 mm CinemaScope reduction prints. To compensate, the premiere engagement of Carousel used a six-track magnetic full-coat in an interlock, and a 1961 re-release of The King and I , featured the film printed down to 70 mm with a six-channel soundtrack. Eventually, 50 complete sets of combination 55/35 mm projectors and penthouse reproducers were completed and delivered by Century and Ampex, respectively, and 55 mm release print sound equipment

12648-449: The rear radiation from the moving diaphragm. A sealed enclosure prevents transmission of the sound emitted from the rear of the loudspeaker by confining the sound in a rigid and airtight box. Techniques used to reduce the transmission of sound through the walls of the cabinet include thicker cabinet walls, internal bracing and lossy wall material. However, a rigid enclosure reflects sound internally, which can then be transmitted back through

12784-418: The rear sound radiation so it can add constructively to the output from the front of the cone. Designs that do this (including bass reflex , passive radiator , transmission line , etc.) are often used to extend the effective low-frequency response and increase the low-frequency output of the driver. To make the transition between drivers as seamless as possible, system designers have attempted to time align

12920-421: The recording head 45 degrees off to the right side so that both the low-frequency rumble and high-frequency distortion were shared equally by both channels, producing the 45/45 system we know today. In 1952, Emory Cook (1913–2002), who already had become famous by designing new feedback disk-cutter heads to improve sound from tape to vinyl, took the two-channel high-fidelity system described above and developed

13056-423: The records not be played on home equipment due to incompatible recording format and speed, they would not even fit on the player, which suited the copyright holders. An experimental format in the 1920s split the signal into two parts, bass and treble, and recording the treble on its own track near the edge of the disc in a lateral format minimizing high-frequency distortion, and recording the bass on its own track in

13192-575: The rising popularity of radio broadcasting and the phonograph , and the Compagnie du Théâtrophone ceased its operations in 1932. Similar systems elsewhere in Europe included Telefon Hírmondó (est. 1893) of Budapest and Electrophone of London (est. 1895). In the United States , the systems similar to théâtrophone were limited to one-off experiments. Erik Barnouw reported a concert by telephone that

13328-583: The same left, center, right and surround sound of the original CinemaScope system of 1953 by using a single standard-width optical track. This important development, marketed as Dolby Stereo , finally brought stereo sound to so-called flat (non- anamorphic ) widescreen films, most commonly projected at aspect ratios of 1.75:1 or 1.85:1. Producers often took advantage of the six magnetic soundtracks available for 70 mm film release prints, and productions shot in either 65 mm or to save money, in 35 mm and then blown up to 70 mm. In these instances,

13464-687: The same year, twenty-five years before that method became the standard for stereo phonograph discs. These discs used the two walls of the groove at right angles in order to carry the two channels. In 1934, Blumlein recorded Mozart 's Jupiter Symphony conducted by Sir Thomas Beecham at Abbey Road Studios in London using his vertical-lateral technique. Much of the development work on this system for cinematic use did not reach completion until 1935. In Blumlein's short test films (most notably, "Trains at Hayes Station", which lasts 5 minutes 11 seconds, and, "The Walking & Talking Film"), his original intent of having

13600-635: The screen, two surround channels in the rear of the theater, plus a sync track to interlock the four machines, which were specially outfitted with aircraft servo-motors made by Ampex . The advent of multitrack magnetic tape and film recording of this nature made high-fidelity synchronized multichannel recording more technically straightforward, though costly. By the early 1950s, all of the major studios were recording on 35 mm magnetic film for mixing purposes, and many of these so-called individual angles still survive, allowing for soundtracks to be remixed into stereo or even surround. In April 1953, while This

13736-433: The signal into individual frequency bands before power amplification, thus requiring at least one power amplifier for each band. Passive filtering may also be used in this way before power amplification, but it is an uncommon solution, being less flexible than active filtering. Any technique that uses crossover filtering followed by amplification is commonly known as bi-amping, tri-amping, quad-amping, and so on, depending on

13872-485: The signal is known as a pan-pot (panoramic potentiometer). By combining multiple pan-potted mono signals together, a complete, yet entirely artificial, sound field can be created. In technical usage, true stereo means sound recording and sound reproduction that uses stereographic projection to encode the relative positions of objects and events recorded. During two-channel stereo recording, two microphones are placed in strategically chosen locations relative to

14008-430: The somewhat disconcerting effect of the actor being on one side of the screen whilst his voice appeared to come from the other. Blumlein declared to his wife that he had found a way to make the sound follow the actor across the screen. The genesis of these ideas is uncertain, but he explained them to Isaac Shoenberg in the late summer of 1931. His earliest notes on the subject are dated 25 September 1931, and his patent had

14144-509: The sound follow the actor was fully realized. In the United States, Harvey Fletcher of Bell Laboratories was also investigating techniques for stereophonic recording and reproduction. One of the techniques investigated was the wall of sound , which used an enormous array of microphones hung in a line across the front of an orchestra. Up to 80 microphones were used, and each fed a corresponding loudspeaker, placed in an identical position, in

14280-405: The sound source, with both recording simultaneously. The two recorded channels will be similar, but each will have distinct time-of-arrival and sound-pressure-level information. During playback, the listener's brain uses those subtle differences in timing and sound level to triangulate the positions of the recorded objects. Since each microphone records each wavefront at a slightly different time,

14416-469: The sound system developed for House of Wax , dubbed WarnerPhonic, was a combination of a 35 mm fully coated magnetic film that contained the audio tracks for left, center and right speakers, interlocked with the two dual-strip Polaroid system projectors, one of which carried a mono optical surround track and one that carried a mono backup track use in the event anything should go wrong. Only two other films featured this unique hybrid WarnerPhonic sound:

14552-496: The speaker can be measured independently of room effects, or any of several electronic techniques that, to some extent, substitute for such chambers. Some developers eschew anechoic chambers in favor of specific standardized room setups intended to simulate real-life listening conditions. Individual electrodynamic drivers provide their best performance within a limited frequency range. Multiple drivers (e.g. subwoofers, woofers, mid-range drivers, and tweeters) are generally combined into

14688-435: The stiffer it is made, the poorer the damping. As a result, many cones are made of some sort of composite material. For example, a cone might be made of cellulose paper, into which some carbon fiber , Kevlar , glass , hemp or bamboo fibers have been added; or it might use a honeycomb sandwich construction; or a coating might be applied to it so as to provide additional stiffening or damping. The chassis, frame, or basket,

14824-426: The subscribers. The service can be called a prototype of the telephone newspaper , as it included five-minute news programs at regular intervals. The Théâtrophone Company set up coin-operated telephone receivers in hotels, cafés, clubs, and other locations, costing 50 centimes for five minutes of listening. The subscription tickets were also issued at a reduced rate, in order to attract regular patrons. The service

14960-436: The system. At the 1939 New York World's Fair , a very large two-way public address system was mounted on a tower at Flushing Meadows . The eight 27" low-frequency drivers were designed by Rudy Bozak in his role as chief engineer for Cinaudagraph. High-frequency drivers were likely made by Western Electric . Altec Lansing introduced the 604 , which became their most famous coaxial Duplex driver, in 1943. It incorporated

15096-534: The throat of a horn for added output level and control of radiation pattern. A tweeter is a high-frequency driver that reproduces the highest frequencies in a speaker system. A major problem in tweeter design is achieving wide angular sound coverage (off-axis response), since high-frequency sound tends to leave the speaker in narrow beams. Soft-dome tweeters are widely found in home stereo systems, and horn-loaded compression drivers are common in professional sound reinforcement. Ribbon tweeters have gained popularity as

15232-474: The théâtrophone can be traced to a telephonic transmission system demonstrated by Clément Ader at the 1881 International Exposition of Electricity in Paris. The system was inaugurated by the French President Jules Grévy , and allowed broadcasting of concerts or plays. Ader had arranged 80 telephone transmitters across the front of a stage to create a form of binaural stereophonic sound . It

15368-424: The title "Improvements in and relating to Sound-transmission, Sound-recording and Sound-reproducing Systems". The application was dated 14 December 1931, and was accepted on 14 June 1933 as UK patent number 394,325 . The patent covered many ideas in stereo, some of which are used today and some not. Some 70 claims include: Blumlein began binaural experiments as early as 1933, and the first stereo discs were cut later

15504-495: The two telephones, the sound takes a special character of relief and localization which a single receiver cannot produce... This phenomenon is very curious, it approximates to the theory of binauricular audition, and has never been applied, we believe, before to produce this remarkable illusion to which may almost be given the name of auditive perspective. This two-channel telephonic process was commercialized in France from 1890 to 1932 as

15640-454: The use of wide-range drivers can avoid undesirable interactions between multiple drivers caused by non-coincident driver location or crossover network issues but also may limit frequency response and output abilities (most especially at low frequencies). Hi-fi speaker systems built with wide-range drivers may require large, elaborate or, expensive enclosures to approach optimum performance. Full-range drivers often employ an additional cone called

15776-464: The vertical plane of recording on disc had the higher fidelity, it was decided to record vertically to produce higher-fidelity recordings on these new materials, for two reasons, the increase in fidelity by avoiding the lateral rumble and to create incompatibility with home phonographs which, with their lateral-only playback systems, would only produce silence from a vertically modulated disc. After 33 + 1 ⁄ 3 RPM recording had been perfected for

15912-405: The voice coil; heating during operation changes resistance, causes physical dimensional changes, and if extreme, broils the varnish on the voice coil; it may even demagnetize permanent magnets. The suspension system keeps the coil centered in the gap and provides a restoring (centering) force that returns the cone to a neutral position after moving. A typical suspension system consists of two parts:

16048-409: The wavefronts are out of phase ; as a result, constructive and destructive interference can occur if both tracks are played back on the same speaker. This phenomenon is known as phase cancellation . Coincident-pair microphone arrangements produce stereo recordings with minimal phase difference between channels. Clément Ader demonstrated the first two-channel audio system in Paris in 1881, with

16184-523: Was Walt Disney's Fantasia , released in November 1940, for which a specialized sound process ( Fantasound ) was developed. As in the Carnegie Hall demonstrations six months earlier, Fantasound used a separate film containing four optical soundtracks. Three of the tracks were used to carry left, center and right audio, while the fourth track carried three tones which individually controlled the volume level of

16320-616: Was a widescreen process featuring three separate 35 mm motion picture films plus a separate sound film running in synchronization with one another at 26 fps, adding one picture panel each to the viewer's left and right at 45-degree angles, in addition to the usual front and center panel, creating a truly immersive panoramic visual experience, comparable in some ways to today's curved screen IMAX OMNI . The Cinerama audio soundtrack technology, developed by Hazard E. Reeves , utilized seven discrete sound tracks on full-coat magnetic 35 mm film. The system featured five main channels behind

16456-420: Was achieved by making the recordings in the form of three motion picture soundtracks recorded on a single piece of film with a fourth track being used to regulate volume expansion. This was necessary due to the limitations of dynamic range on optical motion picture film of the period, however, the volume compression and expansion were not fully automatic, but were designed to allow manual studio enhancement ; i.e.,

16592-421: Was also available to home subscribers. French writer Marcel Proust was a keen follower of théâtrophone, as evident by his correspondence. He subscribed to the service in 1911. Many technological improvements were gradually made to the original théâtrophone system. The Brown telephone relay, invented in 1913, yielded interesting results for amplification of the current. The théâtrophone finally succumbed to

16728-455: Was also reserved for dramas with a strong reliance on sound effects or music, such as The Graduate . The Westrex Stereo Variable-Area system was developed in 1977 for Star Wars , and was no more expensive to manufacture in stereo than it was for mono. The format employs the same Western Electric/Westrex/Nuoptix RA-1231 recorder, and coupled with QS quadraphonic matrixing technology licensed to Dolby Labs from Sansui, this system can produce

16864-417: Was capable of being retrofitted into existing theaters. CinemaScope 55 was created by the same company in order to use a larger form of the system (55 mm instead of 35 mm) to allow for greater image clarity onscreen, and was supposed to have had 6-track stereo instead of four. However, because the film needed a new, specially designed projector, the system proved impractical, and the two films made in

17000-399: Was capable of reproducing clear tones, but later revisions could also reproduce muffled speech . Alexander Graham Bell patented his first electric loudspeaker (a moving iron type capable of reproducing intelligible speech) as part of his telephone in 1876, which was followed in 1877 by an improved version from Ernst Siemens . During this time, Thomas Edison was issued a British patent for

17136-653: Was delivered by Western Electric. Several samples of 55 mm sound prints can be found in the Sponable Collection at the Film and Television Archives at Columbia University . The subsequently abandoned 55/35 mm Century projector eventually became the Century JJ 70/35MM projector. After this disappointing experience with their proprietary CinemaScope 55 mm system, Fox purchased the Todd-AO system and re-engineered it into

17272-481: Was denied patents. Being unsuccessful in selling their product to telephone companies, in 1915 they changed their target market to radios and public address systems , and named their product Magnavox . Jensen was, for years after the invention of the loudspeaker, a part owner of The Magnavox Company. The moving-coil principle commonly used today in speakers was patented in 1925 by Edward W. Kellogg and Chester W. Rice . The key difference between previous attempts and

17408-428: Was invented in 1925 by Edward W. Kellogg and Chester W. Rice . When the electrical current from an audio signal passes through its voice coil —a coil of wire capable of moving axially in a cylindrical gap containing a concentrated magnetic field produced by a permanent magnet —the coil is forced to move rapidly back and forth due to Faraday's law of induction ; this attaches to a diaphragm or speaker cone (as it

17544-525: Was on hand to try out the new technology, recording onto a special proprietary nine-track sound system at the Academy of Music in Philadelphia, during the making of the movie One Hundred Men and a Girl for Universal Pictures in 1937, after which the tracks were mixed down to one for the final soundtrack. A year later, MGM started using three tracks instead of one to record the musical selections of movie soundtracks, and very quickly upgraded to four. One track

17680-578: Was organized in the summer of 1890; around 800 people at the Grand Union Hotel in Saratoga listened to a telephonic transmission of The Charge of the Light Brigade conducted at Madison Square Garden . The Andrew Crumey novel Mr Mee (2000) has a chapter depicting the installation of a théâtrophone in the home of Marcel Proust . The Eça de Queiroz novel A Cidade e as Serras (1901) mentions

17816-548: Was part of an all-Russian program including Mussorgsky 's Pictures at an Exhibition in the Ravel orchestration, excerpts of which were also recorded in stereo. Bell Laboratories gave a demonstration of three-channel stereophonic sound on April 27, 1933, with a live transmission of the Philadelphia Orchestra from Philadelphia to Constitution Hall in Washington, D.C. over multiple Class A telephone lines. Leopold Stokowski, normally

17952-492: Was present at the demonstration, commented that it was "marvellous" but "somehow unmusical because of the loudness." "Take that Pictures at an Exhibition ", he said. "I didn't know what it was until they got well into the piece. Too much 'enhancing', too much Stokowski." In 1937, Bell Laboratories in New York City gave a demonstration of two-channel stereophonic motion pictures, developed by Bell Labs and Electrical Research Products, Inc. Once again, conductor Leopold Stokowski

18088-431: Was run separately through the plating process, lined up to match, and subsequently mounted in a press. The dual-sided stereo disc was then played vertically, first in a system that featured two tonearms on the same post facing one another. The system had trouble keeping the two tonearms in their respective synchronous revolutions. Five years later, Bell Labs was experimenting with a two-channel lateral-vertical system, where

18224-539: Was the first two-channel audio system, and consisted of a series of telephone transmitters connected from the stage of the Paris Opera to a suite of rooms at the Paris Electrical Exhibition, where the visitors could hear Comédie-Française and opera performances in stereo using two headphones; the Opera was located more than two kilometers away from the venue. In a note dated 11 November 1881, Victor Hugo describes his first experience of théâtrophone as pleasant. In 1884,

18360-597: Was used for dialogue, two for music, and one for sound effects. The very first two-track recording MGM made (although released in mono) was "It Never Rains But What It Pours" by Judy Garland , recorded on June 21, 1938, for the movie Love Finds Andy Hardy . In the early 1940s, composer-conductor Alfred Newman directed the construction of a sound stage equipped for multichannel recording for 20th Century Fox studios. Several soundtracks from this era still exist in their multichannel elements, some of which have been released on DVD, including How Green Was My Valley , Anna and

18496-422: Was used for the first time in films, most motion pictures – even some from which stereophonic soundtrack albums were made, such as Zeffirelli 's Romeo and Juliet  – were still released in monaural sound, stereo being reserved almost exclusively for expensive musicals such as West Side Story , My Fair Lady and Camelot , or epics such as Ben-Hur and Cleopatra . Stereo

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