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			{{short description\|High-quality reproduction of sound}}
	{{Original research\|date=July 2009}}
			{{Other uses}}
	{{Otheruses4\|audiophile sound systems}}
			{{redirect-distinguish\|Hi-Fi\|Wi-Fi\|High-end audio\|Hyphy}}
			{{Use American English\|date=September 2024}}

			] are a key component of quality audio reproduction.]]
	'''High fidelity''' or '''hi-fi''' reproduction is a term used by home stereo listeners and ] enthusiasts (]s) to refer to high-quality ] or ] that are very faithful to the original performance.<ref>{{cite book \|last1=Hartley \|first1=H. A. \|authorlink1= \|title=Audio Design Handbook \|url=http://www.tech-systems-labs.com/books/hartley.pdf \|format=PDF \|accessdate=2009-08-08 \|origyear=1958 \|publisher=Gernsback Library \|location=New York, New York \|id=] Catalog Card No. 57-9007 \|page=200 \|chapter=High fidelity \|quote=I invented the phrase "high fidelity" in 1927 to denote a type of sound reproduction that might be taken rather seriously by a music lover. In those days the average radio or phonograph equipment sounded pretty horrible but, as I was really interested in music, it occurred to me that something might be done about it. \|ref=Hartley}}</ref> Ideally, high-fidelity equipment has minimal amounts of ] and ] and an accurate ] as set out in 1973 by the German '']'' (DIN) standard ]. This standard was well intentioned, but only mildly successful in defining 'high-fidelity'. DIN 45 500 approval provided audio equipment buyers with reassurance that their equipment was capable of good quality reproduction. In theory, only stereo equipment that met the standard could bear the words 'hi-fi', but in practice, the term was widely misapplied to audio products that did not remotely approach the DIN basis specifications.

			'''High fidelity''' (often shortened to '''Hi-Fi''' or '''HiFi''') is the high-quality ].<ref>{{cite book \|last=Hartley \|first=H. A. \|title=Audio Design Handbook \|url=http://www.tech-systems-labs.com/books/hartley.pdf \|archive-url=https://web.archive.org/web/20090127021505/http://www.tech-systems-labs.com/books/hartley.pdf \|url-status=dead \|archive-date=2009-01-27 \|access-date=2009-08-08 \|date=1958 \|publisher=Gernsback Library \|location=New York, New York \|id=] Catalog Card No. 57-9007 \|pages=7, 200 \|chapter=High fidelity \|quote=I invented the phrase 'high fidelity' in 1927 to denote a type of sound reproduction that might be taken rather seriously by a music lover. In those days the average radio or phonograph equipment sounded pretty horrible but, as I was really interested in music, it occurred to me that something might be done about it. \|ref=Hartley}}</ref> It is popular with ]s and ] enthusiasts. Ideally, high-fidelity equipment has inaudible ] and ], and a flat (neutral, uncolored) ] within the ].<ref>{{cite web\|url=http://www.hi-fiworld.co.uk/amplifiers/75-amp-tests/147-frequency-response.html\|title=Frequency Response\|website=Hi-FiWorld.co.uk }}</ref>
	By the 1990s, the term hi-fi for expensive high-quality home-audio electronics was largely replaced with '']''.{{Fact\|date=October 2009}}

			High fidelity contrasts with the lower-quality "]" sound produced by inexpensive audio equipment, ], or the inferior quality of sound reproduction that can be heard in recordings made until the late 1940s.

	== History ==		== History ==
			] began experimenting with various recording techniques in the early 1930s. Performances by ] and the ] were recorded in 1931 and 1932 using telephone lines between the ] in Philadelphia and the Bell labs in New Jersey. Some ]s were made on optical sound film, which led to new advances used primarily by ] (as early as 1937) and ] (as early as 1941). ] began recording performances by several orchestras using optical sound around 1941, resulting in higher-fidelity masters for ]s. During the 1930s, ], an amateur violinist, began experimenting with audio design and ]. He wanted to make a radio that would sound like he was listening to a live orchestra and achieve high fidelity to the original sound. After ], ] conducted an experiment whereby test subjects listened to a live orchestra through a hidden variable acoustic filter. The results proved that listeners preferred high-fidelity reproduction, once the noise and distortion introduced by early sound equipment was removed.{{citation needed\|date=November 2019}}

			Beginning in 1948, several innovations created the conditions that made major improvements in home audio quality possible:
	The ] saw the introduction of ], ]s, and the application of quantitative engineering principles to the reproduction of sound. Much of the pioneering work was done at ] and commercialized by ]. ]-recorded ] with capriciously peaky ] were replaced with electrically recorded records. The ] Orthophonic ], although purely acoustic, was created by engineers who applied ] technology to the design of the interior folded horn to produce a smooth frequency response which complemented and equalled that of the electrically recorded Victor Orthophonic records.
			* ], based on technology taken from Germany after WWII, helped musical artists such as ] make and distribute recordings with better fidelity.
			* The advent of the 33⅓ rpm ] (LP) microgroove ], with lower ] and quantitatively specified ] as well as noise-reduction and dynamic range systems. ] fans, who were ] in the audio market, quickly adopted LPs because, unlike with older records, most classical works would fit on a single LP.
			* Higher quality ], with more responsive ]
			* ], with wider audio bandwidth and less susceptibility to signal interference and fading than ].
			* Better ] designs, with more attention to frequency response and much higher power output capability, reproducing audio without perceptible ].<ref name="Lander">{{cite magazine \|url=http://www.americanheritage.com/articles/magazine/ah/2006/3/2006_3_13.shtml \|author=David Lander \|archive-url=https://web.archive.org/web/20070223172555/http://www.americanheritage.com/articles/magazine/ah/2006/3/2006_3_13.shtml \|archive-date=2007-02-23 \|title=The Buyable Past: Classic Hi-Fi Components \|magazine=American Heritage \|date=June–July 2006}}</ref>
			* New ] designs, including ], developed by ] and ] with improved bass frequency response.

			In the 1950s, audio manufacturers employed the phrase ''high fidelity'' as a marketing term to describe records and equipment intended to provide faithful sound reproduction. Many consumers found the difference in quality compared to the then-standard AM radios and 78-rpm records readily apparent and bought high-fidelity phonographs and 33⅓ LPs such as ]'s New Orthophonics and London's FFRR (Full Frequency Range Recording, a UK ] system). ]s focused on technical characteristics and bought individual components, such as separate turntables, radio tuners, ]s, ]s and loudspeakers. Some enthusiasts even assembled their loudspeaker systems, with the advent of integrated multi-speaker console systems in the 1950s, ''hi-fi'' became a generic term for home sound equipment, to some extent displacing ''phonograph'' and ''record player''.
	Meanwhile, the rise of ] meant increased popularity for ]s and ], so there was a period of time during which radio ] commonly used loudspeakers and electronic amplifiers to produce sound, while phonographs were still commonly purely mechanical and acoustic. Later, electronic phonographs became available, as stand-alone units or designed to play through consumer's radios. The now ubiquitous ] was first introduced by the ] for this purpose.

			In the late 1950s and early 1960s, the development of ] equipment and recordings led to the next wave of home-audio improvement, and in common parlance ''stereo'' displaced ''hi-fi''. Records were now played on ''a stereo'' (stereophonic phonograph). In the world of the audiophile, however, the concept of ''high fidelity'' continued to refer to the goal of highly accurate sound reproduction and to the technological resources available for approaching that goal. This period is regarded as the "Golden Age of Hi-Fi", when ] equipment manufacturers of the time produced many models considered superior by modern audiophiles, and just before ] (]ized) equipment was introduced to the market, subsequently replacing tube equipment as the mainstream technology.
	The development of ] in the 1930s led motion picture companies to develop amplification and loudspeaker systems to fill movie theaters with good quality sound at a reasonable volume. To achieve this result, they employed loudspeakers with separate sections for low and high frequencies ("]s" and "]s"), connected via an ] network, and more carefully engineered ]. This development exposed the public to better fidelity than home equipment was capable of at the time. Some movie stars purchased movie theater sound equipment for use in their homes but the cost and size put them out of reach for anyone of modest means.

			] combines an audio ] and ] into one unit, and is an example of the "component" approach to assembling a comprehensive sound reproduction system.]]
	After ], several innovations created the conditions for a major improvement of home-audio quality:

			In the 1960s, the ] with the help of the audio manufacturers came up with a definition to identify high-fidelity equipment so that the manufacturers could clearly state if they meet the requirements and reduce misleading advertisements.<ref>{{Cite book\|last=Lachenbruch\|first=David\|url=https://books.google.com/books?id=ewsEAAAAMBAJ&q=high+fidelity+definition&pg=PA47\|title=Billboard\|date=1963-03-23\|publisher=Nielsen Business Media, Inc.\|isbn=\|location=\|pages=47}}</ref>

			A popular type of system for reproducing music beginning in the 1970s was the integrated ]—which combined a phonograph turntable, AM-FM radio tuner, tape player, preamplifier, and power amplifier in one package, often sold with its own separate, detachable or integrated speakers. These systems advertised their simplicity. The consumer did not have to select and assemble individual components or be familiar with impedance and power ratings. Purists generally avoid referring to these systems as high fidelity, though some are capable of very good quality sound reproduction.
	* ], based on technology found in Germany after the war, helped musical artists such as ] make and distribute recordings with better fidelity.
	* The advent of the 33⅓ ] Long Play (LP) microgroove ], with low surface noise and quantitatively-specified ]. ] fans, who were ] in the audio market quickly adopted LPs because, unlike with older records, most classical works would fit on a single LP.
	* ], with wider audio bandwidth and less susceptibility to signal interference and fading than ], though AM could be heard at longer distances at night.
	* Better ] designs, with more attention to frequency response and much higher power output capability, allowing audio peaks to be reproduced without ].

			Audiophiles in the 1970s and 1980s preferred to buy each component separately. That way, they could choose models of each component with the specifications that they desired. In the 1980s, several audiophile magazines became available, offering reviews of components and articles on how to choose and test speakers, amplifiers, and other components.
	In the 1950s, the term ''high fidelity'' began to be used by audio manufacturers as a marketing term to describe records and equipment which were intended to provide faithful sound reproduction. While some consumers simply interpreted ''high fidelity'' as fancy and expensive equipment, many found the difference in quality between "hi-fi" and the then standard AM radios and 78 RPM records readily apparent and bought 33 LPs, such as RCA's New Orthophonics and London's ffrrs, and high-fidelity phonographs. Audiophiles paid attention to technical characteristics and bought individual components, such as separate turntables, radio tuners, ]s, power amplifiers and loudspeakers. Some enthusiasts assembled their own loudspeaker systems. In the 1950s, ''hi-fi'' became a generic term, to some extent displacing ''phonograph'' and ''record player''.

			== Listening tests ==
	In the late 1950s and early 1960s, the development of the Westrex single-groove ] record led to the next wave of home-audio improvement, and in common parlance, ''stereo'' displaced ''hi-fi''. Records were now played on ''a stereo''. In the world of the audiophile, however, ''high fidelity'' continued and continues to refer to the goal of highly-accurate sound reproduction and to the technological resources available for approaching that goal. This period is most widely regarded as "The Golden Age of Hi-Fi", when tube equipment manufacturers of the time produced many models considered endearing by modern audiophiles, and just before solid state equipment was introduced to the market, subsequently replacing tube equipment as mainstream.
			{{See also\|Codec listening test}}
			Listening tests are used by hi-fi manufacturers, audiophile magazines, and ] researchers and scientists. If a listening test is done in such a way that the listener who is assessing the sound quality of a component or recording can see the components that are being used for the test (e.g., the same musical piece listened to through a tube power amplifier and a solid-state amplifier), then it is possible that the listener's pre-existing biases towards or against certain components or brands could affect their judgment. To respond to this issue, researchers began to use ], in which listeners cannot see the components being tested. A commonly used variant of this test is the ]. A subject is presented with two known samples (sample ''A'', the reference, and sample ''B'', an alternative), and one unknown sample ''X,'' for three samples total. ''X'' is randomly selected from ''A'' and ''B'', and the subject identifies ''X'' as being either ''A'' or ''B''. Although there is no way to prove that a certain methodology is ],<ref>{{cite book\|author=Spanos, Aris\|year=1999\|title= Probability Theory and Statistical Inference \|publisher= Cambridge University Press \|page=699 \|isbn= 0-521-42408-9}}</ref> a properly conducted double-blind test can prove that a method is ''not'' transparent.

			Blind tests are sometimes used as part of attempts to ascertain whether certain audio components (such as expensive, exotic cables) have any subjectively perceivable effect on sound quality. Data gleaned from these blind tests is not accepted by some audiophile magazines such as '']'' and '']'' in their evaluations of audio equipment. ], current editor of ''Stereophile'', stated that he once purchased a solid-state amplifier, the Quad 405, in 1978 after seeing the results from blind tests, but came to realize months later that "the magic was gone" until he replaced it with a tube amp.<ref>{{cite web \|url=http://www.stereophile.com/asweseeit/705awsi \|date=2005-07-17 \|author=John Atkinson \|title=Blind Tests & Bus Stops}}</ref> Robert Harley of ''The Absolute Sound'' wrote, in 2008, that: "...blind listening tests fundamentally distort the listening process and are worthless in determining the audibility of a certain phenomenon."<ref>{{cite web\|url=http://www.avguide.com/forums/blind-listening-tests-are-flawed-editorial?page=2 \|author=Robert Harley \|title=Blind Listening Tests are Flawed: An Editorial \|publisher=The Absolute Sound \|date=2008-05-28 \|access-date=2011-09-29 \|url-status=dead \|archive-url=https://web.archive.org/web/20110930084747/http://www.avguide.com/forums/blind-listening-tests-are-flawed-editorial?page=2 \|archive-date=2011-09-30 }}</ref>
	A very popular type of system for reproducing music from the 1970s onwards was the integrated ] which combined phonograph, radio tuner, tape player, preamp and power amplifier in one package, often sold with its own separate, detachable or integrated speakers. These systems advertised their simplicity; the consumer did not have to select and assemble the individual components. Purists generally avoid referring to these systems as high fidelity, though some are capable of very good quality sound reproduction.

			Doug Schneider, editor of the online Soundstage network, argued the opposite in 2009.<ref>{{cite web\|url=http://www.goodsound.com/editorial/200905.htm \|author=Doug Schneider \|title=The Misinformed Misleading the Uninformed – A Bit About Blind Listening Tests \|publisher=GoodSound! \|date=2009-05-01 \|access-date=2011-09-29}}</ref><ref>{{cite web\|url=http://www.goodsound.com/editorial/200906.htm \|author=Doug Schneider \|title=A Bit More About Blind Listening Tests (6/2009) \|publisher=GoodSound! \|date=2009-06-01 \|access-date=2011-09-29}}</ref> He stated: "Blind tests are at the core of the decades' worth of research into loudspeaker design done at ] (NRC). The NRC researchers knew that for their result to be credible within the scientific community and to have the most meaningful results, they had to eliminate bias, and blind testing was the only way to do so." Many Canadian companies such as Axiom, Energy, Mirage, Paradigm, PSB, and Revel use blind testing extensively in designing their loudspeakers. Audio professional Dr. Sean Olive of Harman International shares this view.<ref>{{cite web\|author=Dr. Sean Olive \|url=http://seanolive.blogspot.com/2009/04/dishonesty-of-sighted-audio-product.html \|title=The Dishonesty of Sighted Listening Tests \|date=2009-04-09 \|access-date=2011-09-29}}{{self-published inline\|date=May 2020}}</ref>
	== Ascertaining high fidelity: double-blind tests ==
	{{Main\|ABX test}}

			==Semblance of realism==
	In a ] experiment, neither the individuals nor the researchers know who belongs to the control group and the experimental group. Only after all the data has been recorded (and in some cases, analyzed) do the researchers learn which individuals are which. A commonly-used variant of this test is the ]. This involves comparing two known audio sources (A and B) with either one of these when it has been randomly selected (X). If two data encodings of a sound are given the same score in a double blind test, in practice, the two sounds are said to be ]—to have no subjective difference.<ref>Pohlmann, Ken C. ''Principles of Digital Audio'', 5th edition, p. 408. McGraw-Hill Professional, 2005. ISBN 0071441565</ref>
			] sound provided a partial solution to the problem of reproducing the sound of live orchestral performers by creating separation among instruments, the ] of space, and a phantom central channel. An attempt to enhance reverberation was tried in the 1970s through ]. Consumers did not want to pay the additional costs and space required for the marginal improvements in realism. With the rise in popularity of ], however, multi-channel playback systems became popular, and many consumers were willing to tolerate the six to eight channels required in a home theater.

			In addition to spatial realism, the playback of music must be subjectively free from noise, such as hiss or hum, to achieve realism. The ] (CD) provides about 90 ]s of ],<ref name="Fries2005">{{cite book \|title=Digital Audio Essentials \|last=Fries \|first=Bruce \|author2=Marty Fries \|year=2005 \|publisher=O'Reilly Media \|isbn=0-596-00856-2 \|pages=–147 \|url=https://archive.org/details/digitalaudioesse0000frie \|url-access=registration \|quote=Digital audio at 16-bit resolution has a theoretical dynamic range of 96 dB, but the actual dynamic range is usually lower because of overhead from filters that are built into most audio systems." ... "Audio CDs achieve about a 90-dB signal-to-noise ratio." "Most adults can't hear frequencies higher than 15 kHz, so the 44.1 kHz sampling rate of CD audio is more than adequate to reproduce the highest frequencies most people can hear.}}</ref> which exceeds the 80 dB dynamic range of music as normally perceived in a concert hall.<ref>{{cite book \|title=Handbook of Recording Engineering \|last=Eargle \|first=John \|author-link=John M. Eargle \|year=2005 \|publisher=Springer \|isbn=0-387-28470-2 \|page=4 \|url=https://books.google.com/books?id=00m1SlorUcIC&pg=PA4 }}</ref> Audio equipment must be able to reproduce frequencies high enough and low enough to be realistic. The human hearing range, for healthy young persons, is 20 Hz to 20,000 Hz.<ref>{{cite web
	== Semblance of realism ==
			\| url=https://hypertextbook.com/facts/2003/ChrisDAmbrose.shtml
			\| title=Frequency range of human hearing
			\| first=Christoper
			\| last=D'Ambrose
			\| year=2003
			\| first2=Rizwan
			\| last2=Choudhary
			\| website=The Physics Factbook
			\| editor-last=Elert
			\| editor-first=Glenn
			\| accessdate=2022-01-22
			}}</ref> Most adults can't hear higher than 15,000 Hz.<ref name="Fries2005"/> CDs are capable of reproducing frequencies as low as 0 Hz and as high as 22,050 Hz, making them adequate for reproducing the frequency range that most humans can hear.<ref name="Fries2005"/> The equipment must also provide no noticeable distortion of the ] or emphasis or de-emphasis of any frequency in this frequency range.

			== Modularity {{anchor\|integrated\|mini\|lifestyle\|midi}}==
	When high fidelity was limited to ] sound reproduction, a realistic approximation to what the listener would experience in a ] was limited. The general clarity of the sound, however, was not any less than with stereophonic sound reproduction. Researchers quickly realized that the ideal way to experience music played back on audio equipment was through multiple transmission channels, but the ] was not available at that time. It was, for example, discovered that a realistic representation of the separation between performers in an ] from an ideal listening position in the concert hall would require at least three loudspeakers for the front channels.{{Fact\|date=October 2009}} For the reproduction of the ], at least two loudspeakers placed behind or to the sides of the listener were required.{{Fact\|date=October 2009}}
			] and ], (from the bottom) an audio digital receiver, DVD player, and HD TV receiver]]

			]
	] sound provided a partial solution to the problem of creating some semblance of the ] of performers performing in an orchestra by creating a phantom middle channel when the listener sits exactly in the middle of the two front loudspeakers. When the listener moves slightly to the side, however, this phantom channel disappears or is greatly reduced. An attempt to provide for the reproduction of the reverberation was tried in the 1970s through ] but, again, the technology at that time was insufficient for the task. ] did not want to pay the additional costs required in ] and space for the marginal improvements in realism. With the rise in popularity of ], however, multi-channel playback systems became affordable, and many consumers were willing to tolerate the six to eight channels required in a home theatre. The advances made in ] to synthesize an approximation of a good concert hall can now provide a somewhat more realistic illusion of listening in a concert hall.

			''Integrated'', ''mini'', or ''lifestyle'' systems (also known by the older terms '']'' or ''midi system''<ref name="argos_midi" /><ref name="matsui_midi_47" />) contain one or more sources such as a ], a ], or a ] deck together with a ] and a ] in one box. A limitation of an "integrated" system is that failure of any one component can possibly lead to the need to replace the entire unit, as components are not readily swapped in or out of a system merely by plugging and unplugging cables, and may not even have been made available by the manufacturer to allow piecemeal repairs.
	In addition to spatial realism, the playback of ] must be subjectively free from noise to achieve realism. The ] (CD) provides at least 90 ]s of ], which is about as much as most people can tolerate in an average ]. This therefore requires the playback equipment to provide a ] of at least 90 decibels.

			Although some ] manufacturers do produce integrated systems, such products are generally disparaged by ]s, who prefer to build a system from ''separates'' (or ''components''), often with each item from a different manufacturer specialising in a particular component. This provides the most flexibility for piece-by-piece ]s and repairs.
	Audio equipment must be able to reproduce frequencies high enough and low enough to be realistic. Many adults over 25 or 30 can hear up to, at most, 15 kHz.<ref name = Ranada> {{cite web \| last = Ranada \| first = David \| url = http://www.soundandvisionmag.com/features/1558/spraying-for-mosquitos.html \| title = Spraying for Mosquitos: High frequencies wasted on the young \| year = 2006 \| month = June \| publisher = ''Sound & Vision'' \| accessdate = 2008-08-04}}</ref> A few younger people can hear up to 19 kHz.<ref name = Ranada2> {{cite web \| last = Ranada \| first = David \| url = http://www.soundandvisionmag.com/features/1558/spraying-for-mosquitos-page2.html \| title = Spraying for Mosquitos: High frequencies wasted on the young \| year = 2006 \| month = June \| publisher = ''Sound & Vision'' \| accessdate = 2008-08-04}}</ref> CDs are capable of reproducing high frequencies up to 22.05 kHz<ref name = Ranada />
	and low frequencies down to 10 Hz.<ref name = Nousaine> {{cite web \| last = Nousaine \| first = Tom \| url = http://www.soundandvisionmag.com/tips/664/big-bad-bass-tracks.html \| title = Big, Bad Bass Tracks \| year = 2004 \| month = September \| publisher = ''Sound & Vision'' \| accessdate = 2008-08-04}}</ref>

			A preamplifier and a power amplifier in one box is called an '']''; with a tuner added, it is a '']''. A monophonic power amplifier is called a ''monoblock'' and is often used for powering a ]. Other modules in the system may include components like ], ]s, hi-fi ]s, ]s, ] players that play a wide variety of discs including ]s, ]s, ] recorders, hi-fi ]s (VCRs) and ]s. Signal modification equipment can include ] and ].
	The equipment must also provide no noticeable distortion of the ] or emphasis or de-emphasis of any frequency in this frequency range. Except for spatial realism, good modern equipment can easily satisfy all of these requirements at a relatively moderate cost.{{Fact\|date=October 2009}}

			This modularity allows the enthusiast to spend as little or as much as they want on a component to suit their specific needs, achieve a desired sound, and add components as desired. Also, failure of any component of an integrated system can render it unusable, while the unaffected components of a modular system may continue to function. A modular system introduces the complexity of cabling multiple components and often having different ]s for each unit.
	== Modularity ==

			== Modern equipment ==
	''Integrated'', ''midi'', or ''lifestyle'' systems, also known as ]s, contain one or more sources such as a ], a ], or a ] deck together with a ] and a ] in one box. (''Midi'' has no connection with ] technology in electronic instruments.) Such products are generally disparaged by ]s, although some ] manufacturers do produce integrated systems. The traditional hi-fi enthusiast, however, will build a system from ''separates'', often with each item from a different manufacturer specialising in a particular component. This provides the most flexibility for piece-by-piece upgrades.
			{{unreferenced section\|date=February 2022}}
			Some modern hi-fi equipment can be digitally connected using ] ] cables, ] ports (including one to play digital audio files), or ] support.

			Another modern component is the ''music server'' consisting of one or more ] ]s that hold music in the form of ]s. When the music is stored in an ] that is ] such as ], ] or ], the computer playback of recorded audio can serve as an audiophile-quality source for a hi-fi system. There is now a push from certain streaming services to offer hi-fi services.
	For slightly less flexibility in ]s, a ] and a power ] in one box is called an ]; with a tuner, it is a '']''. A monophonic power amplifier, which is called a '']'', is often used for powering a ]. Other modules in the system may include components like ], ]s, ]s, ]s, ]s, ] players that play a wide variety of discs including ]s, ]s, ] recorders, hi-fi ]s (VCRs) and ] ]s. Signal modification equipment can include ] and ]s.

	This modularity allows the enthusiast to spend as little or as much as he wants on a component that suits his specific needs. In a system built from separates, sometimes a failure on one component still allows partial use of the rest of the system. A repair of an integrated system, though, means complete lack of use of the system.

	Another advantage of modularity is the ability to spend one's money on only a few core components at first and then later add additional components to one's system. Because of all these advantages to the modular way of building a high-fidelity system instead of buying an integrated system, audiophiles almost always assemble their system from separates.{{Fact\|date=October 2009}} Some of the disadvantages of this approach are increased cost, complexity, and space required for the components.

	== Modern equipment ==

			Streaming services typically have a modified dynamic range and possibly bit rates lower than audiophile standards.{{Citation needed \|date=February 2024 \|reason=The statement may be outdated.}} ] and others have launched a hi-fi tier that includes access to FLAC and ] studio masters for many tracks through the desktop version of the player. This integration is also available for high-end audio systems.
	Modern hi-fi equipment can include signal sources such as ] (DAT), ] (DAB) or ] tuners. Some modern hi-fi equipment can be digitally connected using ] ] cables, ] (USB) ports (including one to play digital audio files), or ] support.

	== See also ==		== See also ==
	{{colbegin}}		{{colbegin\|colwidth=20em}}
	* ]		* ]
			* ]
	* ]		* ]
			* ]
	* ]
	* ]		* ]
	* ]		* ]
			* {{slink\|VHS\|Hi-Fi audio system}}
	* ]
			* ]
	* ]
			* ], a ] term derived from hi-fi

	{{colend}}		{{colend}}
	{{High-definition}}

	== References ==		== References ==
			{{Reflist\|refs=
	{{reflist\|2}}
			<ref name="argos_midi">{{cite book\|url=https://www.flickr.com/photos/lavalampmuseum/3591019798/in/album-72157619081815831/\|archive-url=https://web.archive.org/web/20200527084320/https://www.flickr.com/photos/lavalampmuseum/3591019798/in/album-72157619081815831/\|title=Argos Catalogue Autumn/Winter 1986\|publisher=Argos\|pages=258–259\|quote=Midi Systems Scheider 2500R Remote Control Midi System Amstrad MS-45 Midi System Toshiba S103K Midi System \|archive-date=2020-05-27\|date=1986}} </ref>
			<ref name="matsui_midi_47">{{cite web\|url=https://www.flickr.com/photos/crouchingbadger/4434629033/in/photolist-7KSCHg\|title=Matsui MIDI 47\|date=14 March 2010}}</ref>
			}}

			==Further reading==
			* {{cite book \|author1=Janet Borgerson \|author2=Jonathan Schroeder \|date=2017 \|url=https://mitpress.mit.edu/9780262536011/designed-for-hi-fi-living/ \|title=Designed for Hi-Fi Living: The Vinyl LP in Midcentury America \|place=Cambridge, MA \|publisher=MIT Press \|isbn=9780262036238}}

	== External links ==		== External links ==
			{{wiktionary\|high fidelity\|hi-fi\|hifi}}
	* {{dmoz\|/Recreation/Audio/HiFi/\|HiFi}}
	*		*

			{{High-definition}}
			{{Audio players}}

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Latest revision as of 15:31, 2 January 2025

High-quality reproduction of sound For other uses, see High fidelity (disambiguation). "Hi-Fi" redirects here. Not to be confused with Wi-Fi, High-end audio, or Hyphy.

High fidelity (often shortened to Hi-Fi or HiFi) is the high-quality reproduction of sound. It is popular with audiophiles and home audio enthusiasts. Ideally, high-fidelity equipment has inaudible noise and distortion, and a flat (neutral, uncolored) frequency response within the human hearing range.

High fidelity contrasts with the lower-quality "lo-fi" sound produced by inexpensive audio equipment, AM radio, or the inferior quality of sound reproduction that can be heard in recordings made until the late 1940s.

History

Bell Laboratories began experimenting with various recording techniques in the early 1930s. Performances by Leopold Stokowski and the Philadelphia Orchestra were recorded in 1931 and 1932 using telephone lines between the Academy of Music in Philadelphia and the Bell labs in New Jersey. Some multitrack recordings were made on optical sound film, which led to new advances used primarily by MGM (as early as 1937) and Twentieth Century Fox Film Corporation (as early as 1941). RCA Victor began recording performances by several orchestras using optical sound around 1941, resulting in higher-fidelity masters for 78-rpm discs. During the 1930s, Avery Fisher, an amateur violinist, began experimenting with audio design and acoustics. He wanted to make a radio that would sound like he was listening to a live orchestra and achieve high fidelity to the original sound. After World War II, Harry F. Olson conducted an experiment whereby test subjects listened to a live orchestra through a hidden variable acoustic filter. The results proved that listeners preferred high-fidelity reproduction, once the noise and distortion introduced by early sound equipment was removed.

Beginning in 1948, several innovations created the conditions that made major improvements in home audio quality possible:

Reel-to-reel audio tape recording, based on technology taken from Germany after WWII, helped musical artists such as Bing Crosby make and distribute recordings with better fidelity.
The advent of the 33⅓ rpm long play (LP) microgroove vinyl record, with lower surface noise and quantitatively specified equalization curves as well as noise-reduction and dynamic range systems. Classical music fans, who were opinion leaders in the audio market, quickly adopted LPs because, unlike with older records, most classical works would fit on a single LP.
Higher quality turntables, with more responsive needles
FM radio, with wider audio bandwidth and less susceptibility to signal interference and fading than AM radio.
Better amplifier designs, with more attention to frequency response and much higher power output capability, reproducing audio without perceptible distortion.
New loudspeaker designs, including acoustic suspension, developed by Edgar Villchur and Henry Kloss with improved bass frequency response.

In the 1950s, audio manufacturers employed the phrase high fidelity as a marketing term to describe records and equipment intended to provide faithful sound reproduction. Many consumers found the difference in quality compared to the then-standard AM radios and 78-rpm records readily apparent and bought high-fidelity phonographs and 33⅓ LPs such as RCA's New Orthophonics and London's FFRR (Full Frequency Range Recording, a UK Decca system). Audiophiles focused on technical characteristics and bought individual components, such as separate turntables, radio tuners, preamplifiers, power amplifiers and loudspeakers. Some enthusiasts even assembled their loudspeaker systems, with the advent of integrated multi-speaker console systems in the 1950s, hi-fi became a generic term for home sound equipment, to some extent displacing phonograph and record player.

In the late 1950s and early 1960s, the development of stereophonic equipment and recordings led to the next wave of home-audio improvement, and in common parlance stereo displaced hi-fi. Records were now played on a stereo (stereophonic phonograph). In the world of the audiophile, however, the concept of high fidelity continued to refer to the goal of highly accurate sound reproduction and to the technological resources available for approaching that goal. This period is regarded as the "Golden Age of Hi-Fi", when vacuum tube equipment manufacturers of the time produced many models considered superior by modern audiophiles, and just before solid state (transistorized) equipment was introduced to the market, subsequently replacing tube equipment as the mainstream technology.

In the 1960s, the FTC with the help of the audio manufacturers came up with a definition to identify high-fidelity equipment so that the manufacturers could clearly state if they meet the requirements and reduce misleading advertisements.

A popular type of system for reproducing music beginning in the 1970s was the integrated music centre—which combined a phonograph turntable, AM-FM radio tuner, tape player, preamplifier, and power amplifier in one package, often sold with its own separate, detachable or integrated speakers. These systems advertised their simplicity. The consumer did not have to select and assemble individual components or be familiar with impedance and power ratings. Purists generally avoid referring to these systems as high fidelity, though some are capable of very good quality sound reproduction.

Audiophiles in the 1970s and 1980s preferred to buy each component separately. That way, they could choose models of each component with the specifications that they desired. In the 1980s, several audiophile magazines became available, offering reviews of components and articles on how to choose and test speakers, amplifiers, and other components.

Listening tests

Semblance of realism

Stereophonic sound provided a partial solution to the problem of reproducing the sound of live orchestral performers by creating separation among instruments, the illusion of space, and a phantom central channel. An attempt to enhance reverberation was tried in the 1970s through quadraphonic sound. Consumers did not want to pay the additional costs and space required for the marginal improvements in realism. With the rise in popularity of home theater, however, multi-channel playback systems became popular, and many consumers were willing to tolerate the six to eight channels required in a home theater.

In addition to spatial realism, the playback of music must be subjectively free from noise, such as hiss or hum, to achieve realism. The compact disc (CD) provides about 90 decibels of dynamic range, which exceeds the 80 dB dynamic range of music as normally perceived in a concert hall. Audio equipment must be able to reproduce frequencies high enough and low enough to be realistic. The human hearing range, for healthy young persons, is 20 Hz to 20,000 Hz. Most adults can't hear higher than 15,000 Hz. CDs are capable of reproducing frequencies as low as 0 Hz and as high as 22,050 Hz, making them adequate for reproducing the frequency range that most humans can hear. The equipment must also provide no noticeable distortion of the signal or emphasis or de-emphasis of any frequency in this frequency range.

Modularity

Integrated, mini, or lifestyle systems (also known by the older terms music centre or midi system) contain one or more sources such as a CD player, a tuner, or a cassette tape deck together with a preamplifier and a power amplifier in one box. A limitation of an "integrated" system is that failure of any one component can possibly lead to the need to replace the entire unit, as components are not readily swapped in or out of a system merely by plugging and unplugging cables, and may not even have been made available by the manufacturer to allow piecemeal repairs.

Although some high-end audio manufacturers do produce integrated systems, such products are generally disparaged by audiophiles, who prefer to build a system from separates (or components), often with each item from a different manufacturer specialising in a particular component. This provides the most flexibility for piece-by-piece upgrades and repairs.

A preamplifier and a power amplifier in one box is called an integrated amplifier; with a tuner added, it is a receiver. A monophonic power amplifier is called a monoblock and is often used for powering a subwoofer. Other modules in the system may include components like cartridges, tonearms, hi-fi turntables, digital media players, DVD players that play a wide variety of discs including CDs, CD recorders, MiniDisc recorders, hi-fi videocassette recorders (VCRs) and reel-to-reel tape recorders. Signal modification equipment can include equalizers and noise-reduction systems.

This modularity allows the enthusiast to spend as little or as much as they want on a component to suit their specific needs, achieve a desired sound, and add components as desired. Also, failure of any component of an integrated system can render it unusable, while the unaffected components of a modular system may continue to function. A modular system introduces the complexity of cabling multiple components and often having different remote controls for each unit.

Modern equipment

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Some modern hi-fi equipment can be digitally connected using fiber optic TOSLINK cables, USB ports (including one to play digital audio files), or Wi-Fi support.

Another modern component is the music server consisting of one or more computer hard drives that hold music in the form of computer files. When the music is stored in an audio file format that is lossless such as FLAC, Monkey's Audio or WMA Lossless, the computer playback of recorded audio can serve as an audiophile-quality source for a hi-fi system. There is now a push from certain streaming services to offer hi-fi services.

Streaming services typically have a modified dynamic range and possibly bit rates lower than audiophile standards. Tidal and others have launched a hi-fi tier that includes access to FLAC and Master Quality Authenticated studio masters for many tracks through the desktop version of the player. This integration is also available for high-end audio systems.

References

Hartley, H. A. (1958). "High fidelity". Audio Design Handbook (PDF). New York, New York: Gernsback Library. pp. 7, 200. Library of Congress Catalog Card No. 57-9007. Archived from the original (PDF) on 2009-01-27. Retrieved 2009-08-08. I invented the phrase 'high fidelity' in 1927 to denote a type of sound reproduction that might be taken rather seriously by a music lover. In those days the average radio or phonograph equipment sounded pretty horrible but, as I was really interested in music, it occurred to me that something might be done about it.
"Frequency Response". Hi-FiWorld.co.uk.
David Lander (June–July 2006). "The Buyable Past: Classic Hi-Fi Components". American Heritage. Archived from the original on 2007-02-23.
Lachenbruch, David (1963-03-23). Billboard. Nielsen Business Media, Inc. p. 47.
Spanos, Aris (1999). Probability Theory and Statistical Inference. Cambridge University Press. p. 699. ISBN 0-521-42408-9.
John Atkinson (2005-07-17). "Blind Tests & Bus Stops".
Robert Harley (2008-05-28). "Blind Listening Tests are Flawed: An Editorial". The Absolute Sound. Archived from the original on 2011-09-30. Retrieved 2011-09-29.
Doug Schneider (2009-05-01). "The Misinformed Misleading the Uninformed – A Bit About Blind Listening Tests". GoodSound!. Retrieved 2011-09-29.
Doug Schneider (2009-06-01). "A Bit More About Blind Listening Tests (6/2009)". GoodSound!. Retrieved 2011-09-29.
Dr. Sean Olive (2009-04-09). "The Dishonesty of Sighted Listening Tests". Retrieved 2011-09-29.
^ Fries, Bruce; Marty Fries (2005). Digital Audio Essentials. O'Reilly Media. pp. 144–147. ISBN 0-596-00856-2. Digital audio at 16-bit resolution has a theoretical dynamic range of 96 dB, but the actual dynamic range is usually lower because of overhead from filters that are built into most audio systems." ... "Audio CDs achieve about a 90-dB signal-to-noise ratio." "Most adults can't hear frequencies higher than 15 kHz, so the 44.1 kHz sampling rate of CD audio is more than adequate to reproduce the highest frequencies most people can hear.
Eargle, John (2005). Handbook of Recording Engineering. Springer. p. 4. ISBN 0-387-28470-2.
D'Ambrose, Christoper; Choudhary, Rizwan (2003). Elert, Glenn (ed.). "Frequency range of human hearing". The Physics Factbook. Retrieved 2022-01-22.
Argos Catalogue Autumn/Winter 1986. Argos. 1986. pp. 258–259. Archived from the original on 2020-05-27. Midi Systems Scheider 2500R Remote Control Midi System Amstrad MS-45 Midi System Toshiba S103K Midi System Alt URL
"Matsui MIDI 47". 14 March 2010.

External links

A Dictionary of Home Entertainment Terms

v t e High-definition (HD)
Concepts	High-definition television High-definition video Ultra-high-definition television
Resolutions	720p (HD) 1080i (Full HD) 1080p (Full HD) 1440p (Quad HD) 2160p (4K Ultra HD) 4320p (8K Ultra HD) 8640p (16K Ultra HD)
Analog broadcast (All defunct)	819 line system HD MAC MUSE (Hi-Vision)
Digital broadcast	ATSC DMB-T/H DVB ISDB SBTVD
Audio	Dolby Digital Surround sound DSD DXD DTS
Filming and storage	DCI HDV
HD media and compression	Archival Disc AV1 Blu-ray CBHD D-VHS DVD-Audio H.264 H.265 H.266 HD DVD HD VMD MPEG-2 MUSE LaserDisc MVC Super Audio CD Ultra HD Blu-ray Uncompressed VC-1 W-VHS
Connectors	Component DisplayPort DVI HDMI VGA
Deployments	List of digital television deployments by country

v t e Audio players
Home	AV receiver Boombox Cassette deck HiFi High-end audio MP3 player Music centre Portable media player Radiogram Shelf stereo Table radio Tuner Vehicle audio Walkman

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