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87-451: BEAST can consist of up to over 100 channels of loudspeakers , often arranged largely in pairs or rings, and includes ultra-low frequency loudspeakers ( bins ) and custom-built trees of high frequency speakers ( tweeter trees ) which can be suspended above an audience. BEAST was originally designed as an acousmonium -style system for the diffusion of stereo work. The minimum set-up that BEAST would ordinarily use for stereo diffusion comprises

174-421: 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 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

261-435: 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

348-402: 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

435-808: 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,

522-426: 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

609-447: 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 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,

696-426: 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

783-421: 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,

870-406: 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

957-482: 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 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

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1044-458: 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

1131-405: 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

1218-419: 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

1305-414: 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

1392-568: A set of loudspeakers which Jonty Harrison terms the Main Eight . These four pairs of loudspeakers, using BEAST nomenclature, are termed Main , Wide , Distant and Rear . The Main and the Wide speakers together form the main, frontal sound image, the Main speakers being placed to act somewhat like the stereo loudspeakers in a typical studio, and the Wide speakers acting to stretch that sound image out across

1479-483: 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

1566-408: 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

1653-787: 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

1740-411: 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

1827-609: A tape-machine was split passively into the input channels on the desk, alternating left and right. The direct output from each channel fed the amplifiers for the loudspeakers, thus giving the individual control of each loudspeaker required for diffusion. The main disadvantage of this system was that it offered very little flexibility, making it difficult to move between sources in different formats (for example, quadraphonic , octaphonic or pieces with live input). In some situations complicated rewiring would be required for each source format used, which could be prone to errors particularly during

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1914-431: A timestamp, which determines whether the server should respond immediately or at some point in the future. Applications commonly employ extensions to this core set. More recently some of these extensions such as a compact Boolean type were integrated into the required core types of OSC 1.1. The advantages of OSC over MIDI are primarily internet connectivity; data type resolution; and the comparative ease of specifying

2001-410: A type tag string (such as ,fi for a float32 argument followed by an int32 argument), and the arguments themselves (which may include a time tag). Address patterns form a hierarchical name space , reminiscent of a Unix filesystem path, or a URL , and refer to " Methods " inside the server, which are invoked with the attached arguments . Type tag strings are a compact string representation of

2088-445: 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

2175-450: Is a protocol for networking sound synthesizers , computers, and other multimedia devices for purposes such as musical performance or show control . OSC's advantages include interoperability , accuracy, flexibility and enhanced organization and documentation. Its disadvantages include inefficient coding of information , increased load on embedded processors , and lack of standardized messages/interoperability. The first specification

2262-475: 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

2349-416: 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

2436-600: Is built on top of OSC. Similarly the GDIF system for representing gestures integrates OSC. OSC is used extensively in experimental musical controllers, and has been built into several open source and commercial products. The Open Sound World (OSW) music programming language is designed around OSC messaging. OSC is the heart of the DSSI plugin API, an evolution of the LADSPA API, in order to make

2523-551: 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

2610-404: 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

2697-484: 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,

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2784-561: The Aspekte Festival in Salzburg. 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 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

2871-1093: The Edinburgh International Festival , the Inventionen Festival in Berlin, Hello Digital , Huddersfield Contemporary Music Festival , Multimediale 2 in Karlsruhe, in the Purcell Room and the Royal Festival Hall , The Royal Conservatoire in The Hague, the Adrian Boult Hall in Birmingham and the Henry Wood Hall in Glasgow. It was acclaimed when used as the concert sound system at the 1990 International Computer Music Conference held in Glasgow, and at

2958-581: The Open Sound Control protocol, were made for BEAST by Sukhandar Kartadinata based on his GLUI platform. Clones of these desks have been adopted by other users and systems. Since its debut in December 1982, BEAST has performed hundreds of concerts in the UK and Europe, both on its own and in joint performances with musicians from all over the world. BEAST has appeared at many notable festivals and concerts, including

3045-514: 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

3132-406: 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 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

3219-631: 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

3306-418: 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

3393-528: 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

3480-858: The 1983 MIDI standard, when higher resolution and a richer parameter space is desired. OSC messages are transported across the internet and within local subnets using UDP/IP and Ethernet . OSC messages between gestural controllers are usually transmitted over serial endpoints of USB wrapped in the SLIP protocol. OSC's main features, compared to MIDI, include: There are dozens of OSC applications, including real-time sound and media processing environments, web interactivity tools, software synthesizers, programming languages and hardware devices. OSC has achieved wide use in fields including musical expression , robotics, video performance interfaces, distributed music systems and inter-process communication . The TUIO community standard for tangible interfaces such as multitouch

3567-411: 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

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3654-542: 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

3741-426: The argument types. Arguments are represented in binary form with four- byte alignment. The core types supported are An example message is included in the spec (with null padding bytes represented by ␀): /oscillator/4/frequency␀,f␀␀ , Followed by the 4-byte float32 representation of 440.0: 0x43dc0000. Messages may be combined into bundles, which themselves may be combined into bundles, etc. Each bundle contains

3828-595: The audience's sound stage. The Rear speakers, which are behind the audience, provide immersion and the possibility of movement around the audience. Finally, the Distant speakers, which are positioned to hold their image behind the Main speakers, create a sound whose perspective is distant to that of the Main pair. Other speakers are added to this Main Eight to allow additional possibilities for sound movement and differing sound perspectives. More recent work with BEAST has explored

3915-416: 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

4002-449: 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

4089-486: 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

4176-413: 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

4263-746: 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

4350-433: 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. Open Sound Control Open Sound Control ( OSC )

4437-487: 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

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4524-589: 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

4611-501: 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.

4698-422: 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

4785-528: The eventual GUI interact with the core of the plugin via messaging the plugin host. LADSPA and DSSI are APIs dedicated to audio effects and synthesizers. In 2007, a standardized namespace within OSC called SYN, for communication between controllers, synthesizers and hosts, was proposed, Notable software with OSC implementations include: Notable hardware with OSC implementations include: OSC messages consist of an address pattern (such as /oscillator/4/frequency ),

4872-429: 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

4959-433: 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

5046-419: 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,

5133-501: 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

5220-415: 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

5307-454: 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

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5394-420: 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

5481-492: The matrix. BEAST's positive and negative experiences with this experimental desk led them to design a new one: their last analogue desk, called the 3D . This was a fully custom built console with an extensive matrix input which was very easy and flexible to use. With the electroacoustic community's renewed interest in multichannel formats, and in particular octaphonic set-ups, came the need for BEAST to address how such pieces should be diffused. The diffusion of multichannel formats

5568-479: The maximum flexibility, with one fader, for example, being able to control only one loudspeaker, a stereo pair or an octaphonic circle depending on how the system has been configured. Using this system, multiple octaphonic groups, placed in different positions around the audience, can be used to diffuse octaphonic source material in a manner similar to that used for stereo. In this case, each fader controls one octaphonic group. A new set of three fully digital desks, using

5655-451: 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

5742-617: 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

5829-487: 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 ,

5916-429: 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

6003-569: The piece's implied spatial sound detail within the real space of the performance venue, in order to realise and interpret the composer 's intentions. The system also includes equipment for the live processing of sounds so that, for instance, the sounds of a live violinist can be processed and incorporated into the soundstage. The BEAST diffusion console has developed significantly over the years. The earliest systems depended on those commercially available mixing desks which had direct outputs from each fader . The stereo input signal from, for example,

6090-453: 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

6177-405: The possibilities offered by 'massively multichannel' approaches to composition, and 'n-channel' work. BEAST is a dynamic system: during a performance the performer operates an often custom-built console, called the diffusion console, with which he or she can individually and dynamically control the level of each loudspeaker, or groups of loudspeakers. This enables him or her to actively articulate

6264-449: 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

6351-418: 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

6438-455: 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 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

6525-411: 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 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

6612-433: 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

6699-496: 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

6786-435: 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,

6873-454: The stress of a performance. The first custom built console BEAST developed was still based on a commercially available mixing desk, but which had been extensively modified, adding a matrix input section and balanced outputs. The matrix input section allowed a number of inputs to be assigned to any fader input using a series of push buttons. Where multiple sources were used during a concert, this allowed each work to have their assignment preset on

6960-436: 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

7047-534: 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

7134-454: 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

7221-405: 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:

7308-399: 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

7395-481: 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

7482-485: Was released in March 2002. OSC is a content format developed at CNMAT by Adrian Freed and Matt Wright comparable to XML , WDDX , or JSON . It was originally intended for sharing music performance data ( gestures , parameters and note sequences) between musical instruments (especially electronic musical instruments such as synthesizers ), computers, and other multimedia devices. OSC is sometimes used as an alternative to

7569-467: Was too complex a task for the standard BEAST console, even the 3D, and BEAST turned to software solutions to solve these problems: first MAX/MSP and most recently, a system created in SuperCollider by Scott Wilson and Sergio Luque . Now, rather than using an analogue desk, a digital multichannel sound interface is used, and controlled via specially written applications using MIDI faders. This offers

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