Editing Audio power amplifier (section)

== History ==
[[File:First Audion amplifier 1914.jpg|thumb|left|upright=0.6|De Forest's prototype audio amplifier of 1914]]

The audio amplifier was invented around 1912 by [[Lee de Forest]]. This was made possible by his invention of the first practical amplifying electrical component, the [[triode]] [[vacuum tube]] (or "valve" in British English) in 1907. The [[triode]] was a three-terminal device with a control grid that can modulate the flow of electrons from the filament to the plate. The triode [[Valve amplifier|vacuum amplifier]] was used to make the first [[AM radio]].<ref>[https://web.archive.org/web/20080705150057/http://nobelprize.org/educational_games/physics/transistor/history/ The Transistor in a Century of Electronics]. nobelprize.org</ref> Early audio power amplifiers were based on vacuum tubes and some of these achieved notably high audio quality (e.g., the [[Williamson amplifier]] of 1947–9).
[[File:Mcintosh-MC240-glow.jpg|thumb|right|300px|[[McIntosh Labs|McIntosh]] MC240 from 1961, with exposed vacuum tubes]]

Audio power amplifiers based on [[transistor]]s became practical with the wide availability of inexpensive transistors in the late 1960s. Since the 1970s, most modern audio amplifiers are based on [[Solid-state electronics|solid-state]] transistors, especially the [[bipolar junction transistor]] (BJT) and the [[metal–oxide–semiconductor field-effect transistor]] (MOSFET). Transistor-based amplifiers are lighter in weight, more reliable and require less maintenance than [[tube amplifier]]s.

The MOSFET was invented at [[Bell Labs]] between 1955 and 1960.<ref>{{Cite patent|number=US2802760A|title=Oxidation of semiconductive surfaces for controlled diffusion|gdate=1957-08-13|invent1=Lincoln|invent2=Frosch|inventor1-first=Derick|inventor2-first=Carl J.|url=https://patents.google.com/patent/US2802760A}}</ref><ref>{{Cite journal |last1=Frosch |first1=C. J. |last2=Derick |first2=L |date=1957 |title=Surface Protection and Selective Masking during Diffusion in Silicon |url=https://iopscience.iop.org/article/10.1149/1.2428650 |journal=Journal of the Electrochemical Society |language=en |volume=104 |issue=9 |pages=547 |doi=10.1149/1.2428650}}</ref><ref name="Lojek1202">{{cite book |last1=Lojek |first1=Bo |title=History of Semiconductor Engineering |date=2007 |publisher=[[Springer Science & Business Media]] |isbn=9783540342588 |page=120}}</ref><ref>{{Cite journal |last=KAHNG |first=D. |date=1961 |title=Silicon-Silicon Dioxide Surface Device |url=https://doi.org/10.1142/9789814503464_0076 |journal=Technical Memorandum of Bell Laboratories|pages=583–596 |doi=10.1142/9789814503464_0076 |isbn=978-981-02-0209-5 }}</ref><ref>{{Cite book |last=Lojek |first=Bo |title=History of Semiconductor Engineering |date=2007 |publisher=Springer-Verlag Berlin Heidelberg |isbn=978-3-540-34258-8 |location=Berlin, Heidelberg |page=321}}</ref><ref>{{Cite journal |last1=Ligenza |first1=J.R. |last2=Spitzer |first2=W.G. |date=1960 |title=The mechanisms for silicon oxidation in steam and oxygen |url=https://linkinghub.elsevier.com/retrieve/pii/0022369760902195 |journal=Journal of Physics and Chemistry of Solids |language=en |volume=14 |pages=131–136 |doi=10.1016/0022-3697(60)90219-5|bibcode=1960JPCS...14..131L }}</ref> was adapted into a [[power MOSFET]] for audio by [[Jun-ichi Nishizawa]] at [[Tohoku University]] in 1974.<ref name="Duncan177">{{cite book |last1=Duncan |first1=Ben |title=High Performance Audio Power Amplifiers |date=1996 |publisher=[[Elsevier]] |isbn=9780080508047 |pages=[https://cucdaycongsuat.com.vn/ 177–8, 406] |url=https://cucdaycongsuat.com.vn/ }}</ref> Power MOSFETs were soon manufactured by [[Yamaha Corporation|Yamaha]] for their [[hi-fi]] audio amplifiers. [[JVC]], [[Pioneer Corporation]], [[Sony]] and [[Toshiba]] also began manufacturing amplifiers with power MOSFETs in 1974.<ref name="Duncan177"/> In 1977, [[Hitachi]] introduced the [[LDMOS]] (lateral diffused MOS), a type of power MOSFET. Hitachi was the only LDMOS manufacturer between 1977 and 1983, during which time LDMOS was used in audio power amplifiers from manufacturers such as [[HH Electronics]] (V-series) and [[Ashly Audio]], and were used for music and [[public address system]]s.<ref name="Duncan177"/> [[Class-D amplifier]]s became successful in the mid-1980s when low-cost, fast-switching MOSFETs were made available.<ref>{{cite book |last=Duncan |first=Ben |date=1996 |title=High Performance Audio Power Amplifiers |publisher=Newnes |pages=147–148 |isbn=9780750626293 }}</ref> Many transistor amps use MOSFET devices in their [[power electronics|power]] sections, because their [[distortion (music)|distortion]] curve is more [[tube sound|tube-like]].<ref>{{cite book |last1=Fliegler |first1=Ritchie |last2=Eiche |first2=Jon F. |title=Amps! The Other Half of Rock 'n' Roll |date=1993 |publisher=[[Hal Leonard Corporation]] |isbn=9780793524112 |url=https://books.google.com/books?id=NgG8bmBayLwC&pg=PA19}}</ref>

In the 2010s, there are still audio enthusiasts, musicians (particularly [[electric guitar]]ists, [[electric bass]]ists, [[Hammond organ]] players and [[Fender Rhodes]] [[electric piano]] players, among others), audio engineers and [[music producer]]s who prefer tube-based amplifiers, and what is perceived as a "warmer" [[tube sound]].
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