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| Loudspeakers | |
|---|---|
| Name | Loudspeaker |
| Invented | 19th century |
| Inventors | Alexander Graham Bell, David Edward Hughes, Ernst Siemens |
| Industry | RCA Corporation, General Electric, Bose Corporation, JBL |
Loudspeakers are electroacoustic transducers that convert electrical signals into sound waves, used in consumer electronics, professional audio, and public address systems. They are central to technologies developed by inventors and companies such as Alexander Graham Bell, Emile Berliner, Guglielmo Marconi, and corporations like RCA Corporation and Bose Corporation. Modern devices span designs from dynamic drivers to planar magnetic systems pioneered in research at institutions including Bell Labs and Massachusetts Institute of Technology.
The origins trace to experiments by Alexander Graham Bell, David Edward Hughes, and inventors associated with Siemens AG during the 19th century, and early commercialisation by companies like Western Electric and RCA Corporation. Key milestones include the development of the moving-coil driver by inventors influenced by Michael Faraday and James Clerk Maxwell, patent activity involving figures such as Emile Berliner, and adoption in mass media through entities like Columbia Records and broadcasters British Broadcasting Corporation. Throughout the 20th century, advances at Bell Labs, Philco, and General Electric drove innovations used in venues from Carnegie Hall to stadium systems commissioned by promoters like Bill Graham.
Typical construction integrates a frame or basket derived from practices at manufacturers like JBL and Klipsch Audio Technologies, a cone or diaphragm made with materials studied at DuPont and 3M, a voice coil often wound with copper or aluminum researched at General Motors, a magnetic circuit referencing work by Niels Bohr in magnetics, and a suspension comprising a surround and spider influenced by standards from Institute of Electrical and Electronics Engineers panels. Cabinets and enclosures draw on acoustical engineering advances developed at Massachusetts Institute of Technology and Stanford University, with crossover networks designed using topologies promoted by firms such as Harman International.
Driver technologies include dynamic drivers refined by JBL and Altec Lansing, electrostatic panels advanced by Quad Electroacoustics and MartinLogan, planar magnetic systems commercialised by companies like Audeze, and ribbon transducers used by manufacturers including Burmester. Horn-loaded systems popularised by Eminence and Klipsch contrast with transmission line enclosures explored at BBC Research Department. Subwoofer designs evolved in car audio projects by Alpine Electronics and professional sound systems by d&b audiotechnik.
Performance metrics borrow from theoretical work by Lord Rayleigh and Hermann von Helmholtz, using parameters such as resonance frequency and Q derived from models used at Bell Labs and universities like University of Cambridge. Frequency response and sensitivity measurements rely on standards promulgated by organisations such as International Electrotechnical Commission and IEEE. Directivity and dispersion considerations echo research from Royal Institution experiments and modern beamforming techniques developed at Fraunhofer Society.
Applications range across consumer devices sold by Sony, Samsung, and Apple Inc.; professional audio systems used by venues like Sydney Opera House; cinema soundtracks distributed by studios including Warner Bros.; live sound reinforcement for tours by promoters like Live Nation; public address installations in airports managed by companies such as Honeywell; and assistive listening devices promoted by organisations like World Health Organization.
Manufacturing processes employ stamping, injection molding, and composite layup techniques industrialised by Siemens AG and Siemens Energy, with materials sourced from suppliers such as DuPont and 3M. Magnet materials include ferrite and rare-earth alloys developed by researchers at UMICORE and Sumitomo Metal Mining Co., Ltd.. Quality control and production methods reflect practices from electronics manufacturers like Foxconn and Flex Ltd..
Measurement and certification reference standards from International Electrotechnical Commission (IEC), Institute of Electrical and Electronics Engineers (IEEE), and accreditation by bodies such as Underwriters Laboratories and TÜV SÜD. Laboratory techniques employ anechoic chambers modelled after facilities at National Physical Laboratory (United Kingdom) and National Institute of Standards and Technology, and testing protocols used by industry consortia like AES and CEDIA.
Category:Audio equipment