User:Sebquantic/BMS notes

History

Early history

thumb|right|225px|Edison cylinder phonograph ca. 1899

A device utilizing a vibrating pen to graphically represent sound on discs of paper, without the idea of playing it back in any manner, was built by Édouard-Léon Scott de Martinville of France in 1857. While the mechanism, known as a phonautograph, was intended solely to depict the visual characteristics of sound, it was recently realized that this depiction could be digitally analyzed and reconstructed as an audible recording. Just such an early phonoautogram, made in 1860 and now the earliest known audio recording, has been reproduced using computer technology.

In 1877, Thomas Edison developed the phonautograph into a machine, the phonograph, that was capable of replaying the recordings made. The recordings were made on tinfoil, and were initially intended to be used as a voice recording medium, typically for office dictation.

This phonograph cylinder dominated the recorded sound market beginning in the 1880s. Lateral-cut disc records were invented by Emile Berliner in 1888 and were used exclusively in toys until 1894, when Berliner began marketing disc records under the Berliner Gramophone label. Berliner's records had poor sound quality; however, work by Eldridge R. Johnson improved the fidelity to a point where they were as good as cylinders. Johnson's and Berliner's separate companies merged to form the Victor Talking Machine Company, whose products would come to dominate the market for many years later.^[1]

In an attempt to head off the disc advantage, Edison introduced the Amberol cylinder in 1909, with a maximum playing time of 4½ minutes (at 160 rpm) to be in turn superseded by the Blue Amberol Record whose playing surface was made of Celluloid, an early plastic which was far less fragile than the earlier wax (in fact it would have been more or less indestructible had it not been for the plaster of paris core). By November 1918 the patents for the manufacture of lateral-cut disc records expired, opening the field for countless companies to produce them, causing disc records to overtake cylinders in popularity. Edison ceased production of cylinders in 1929. Disc records would dominate the market until they were supplanted by the Compact Disc, starting from the early 1980s.

standardization

Early disc recordings were produced in a variety of speeds ranging from 60 to 130 rpm, and a variety of sizes.

As early as 1894, Emile Berliner's United States Gramophone Company was selling single-sided 7" discs with an advertised standard speed of "about 70 rpm".^[2]

One standard audio recording handbook describes speed regulators or "governors" as being part of a wave of improvement introduced rapidly after 1897. A picture of a hand-cranked 1898 Victrola shows a governor. It says that spring drives replaced hand drives. It notes that:

"The speed regulator was furnished with an indicator that showed the speed when the machine was running so that the records, on reproduction, could be revolved at exactly the same speed...The literature does not disclose why 78 rpm was chosen for the phonograph industry, apparently this just happened to be the speed created by one of the early machines and, for no other reason continued to be used."^[3]

In America in 1900, the two leading manufacturers of flat records were Columbia, which used 80 rpm as its speed, and Victor, which used 76 rpm. Since one company's records were playable on the other's machines, it is only logical that the eventual standard speed would be in the middle.

By 1925, the speed of the record became standardised at a nominal value of 78 rpm. However, the standard was to differ between America and the rest of the world. The actual 78 speed in America was 78.26 rpm, being the speed of 3600 rpm synchronous motor (run from 60 Hz supply) reduced by 46:1 gearing. Throughout the rest of the world, 77.92 rpm was adopted being the speed of a 3000 rpm synchronous motor powered by a 50 Hz supply and reduced by 38.5:1 gearing.^[4]

In 1925, 78.26 rpm was chosen as the standard because of the introduction of the electrically powered synchronous turntable motor. This motor ran at 3600 rpm, such that a 46:1 gear ratio would produce 78.26 rpm. In parts of the world that used 50 Hz current, the standard was 77.92 rpm (3000 rpm with a 38.5:1 ratio), which was also the speed at which a strobe disc with 77 lines would "stand still" in 50 Hz light (92 lines for 60Hz). After World War II these records were retroactively known as 78s, to distinguish them from other newer disc record formats. Earlier they were just called records, or when there was a need to distinguish them from cylinders, disc records.

Notes:

Before the early 1950s the 33⅓ rpm LP was most commonly found in a 10-inch (25 cm) format. The 10-inch format disappeared from United States stores around 1950, but remained common in some markets until the mid-1960s. The 10-inch vinyl format was resurrected in the 1970s for marketing some popular recordings as collectible, and these are occasionally seen today.
The maximum time per side for an LP is only achievable with special playback styli, so cutting engineers often dislike cutting such grooves^{[citation needed]}.

Electrical transcriptions and 78s were first used as sources to master LP lacquer/aluminum cuts in 1948. This was before magnetic tape was commonly employed for mastering. Variable pitch groove spacing helped enable greater recorded dynamic levels. The heated stylus improved the cutting of high frequencies. Gold sputtering in vacuo became increasingly used to make high quality matrices from the cuts to stamp vinyl records.

Acoustic recording

Early recordings were made entirely acoustically, the sound being collected by a horn and piped to a diaphragm which vibrated the cutting stylus. Sensitivity and frequency range were poor, and frequency response was very irregular, giving cylinder recordings an instantly recognizable tonal quality. A singer practically had to put his face in the recording horn. Cellos and double basses were completely unrecordable. Standard Violins were barely recordable, so Stroh violins became popular with recording studios.

Overall sound fidelity of records produced acoustically using horns instead of microphones had a distant, hollow tone quality. Some voices and instruments recorded better than others; Enrico Caruso, a famous tenor, was one popular recording artist of the acoustic era that was well matched to the recording horn. It has been asked, "Did Caruso make the phonograph or did the phonograph make Caruso?"

Delicate sounds and fine overtones were mostly lost because it took a lot of sound energy to vibrate the recording horn diaphragm and cutting mechanism. There were acoustic limitations due to mechanical resonances in both the recording and playback system. Some pictures of acoustic recording sessions show horns wrapped with tape to help mute these resonances. Even an acoustic recording played back electrically on modern equipment sounds like it was recorded through a horn, not withstanding a 50% reduction in distortion because of the modern playback. Towards the end of the acoustic era, there were many fine examples of recordings made with horns.

Contrary to popular belief, if placed properly and prepared-for, drums could be effectively used and heard on even the earliest jazz and military band recordings. The loudest instruments stood the farthest away from the collecting horn. Lillian Hardin Armstrong, a member of King Oliver's Creole Jazz Band that recorded at Gennett Records in 1923, remembered that at first Oliver and his young second trumpet, Louis Armstrong, stood next to each other and Oliver's horn couldn't be heard. "They put Louis about fifteen feet over in the corner, looking all sad."^[5]^[6]

"Electrical" recording

thumb|left|177px|German electrical record of the Carl Lindström AG

During the 1920s, engineers including Orlando R. Marsh, as well as those at Western Electric, developed technology for capturing sound with microphones, amplifying it with vacuum tubes, and using the amplified signal to drive an electromagnetic recording head. A wide frequency range could now be recorded with a big increase in playback volume limited only by the pitch of the grooves in the record.

Although the technology used vacuum tubes and today would be described as "electronic", at the time it was referred to as "electrical". A 1926 Wanamaker's ad in The New York Times offers records "by the latest Victor process of electrical recording".^[7] It was recognized as a breakthrough; in [1930], a Times music critic stated:

"...the time has come for serious musical criticism to take account of performances of great music reproduced by means of the records. To claim that the records have succeeded in exact and complete reproduction of all details of symphonic or operatic performances... would be extravagant. [But] the article of today is so far in advance of the old machines as hardly to admit classification under the same name. Electrical recording and reproduction have combined to retain vitality and color in recitals by proxy."^[8]

Electrical recording preceded electrical home reproduction (much as digital recording preceded digital home reproduction), because of the initial high cost of the electronics. In 1925, the Victor company introduced the groundbreaking Victor Orthophonic Victrola, an acoustical record player that was specifically designed to play electrically recorded discs, as part of a line that also included electrically-reproducing "Electrolas." The acoustical Orthophonics ranged in price from US$95 to $300 (about US$1140 to $3600 in year 2007 dollars), depending on cabinetry; by comparison, the cheapest Electrola cost US$650 (about US$7500 in year 2007 dollars).

The Orthophonic had an interior folded exponential horn, a sophisticated design informed by impedance-matching and transmission-line theory, and designed to provide a relatively flat frequency response. Its first public demonstration was front-page news in the New York Times, which reported that:

"The audience broke into applause... John Philip Sousa [said]: 'Gentleman [sic], that is a band. This is the first time I have ever heard music with any soul to it produced by a mechanical talking machine.' ... The new instrument is a feat of mathematics and physics. It is not the result of innumerable experiments, but was worked out on paper in advance of being built in the laboratory.... The new machine has a range of from 100 to 5,000 frequencies[sic], or five and a half octaves.... The 'phonograph tone' is eliminated by the new recording and reproducing process."^[9]

Gradually, electrical reproduction entered the home. The clockwork motor was replaced by an electric motor; the 'needle' and diaphragm (the 'sound box') was replaced with a 'pickup' using either a steel or sapphire stylus, and a transducer to convert the groove vibrations into an electrical signal. The exponential horn became an amplifier and loudspeaker.^{[citation needed]}

Electric recording which developed during the time that early radio was becoming popular (1925) benefited from the microphones and amplifiers used in radio studios. The early electric recordings were reminiscent tonally of acoustic recordings except there was more recorded bass and treble as well as delicate sounds and overtones cut on the records. This was in spite of some carbon microphones used which had resonances that colored the recorded tone. The double button carbon microphone with stretched diaphragm was a marked improvement. Alternatively, the Wente style condenser microphone used with the Western Electric (W. E.) licensed recording method had a brilliant midrange and was prone to overloading from sibilants in speech, but it was generally better at picking up sounds more accurately than carbon microphones were.

It was not unusual, however, for electric recordings to be played back on acoustic phonographs. The Victor Orthophonic phonograph was a prime example where such playback was expected. In the Orthophonic, which benefited from telephone research, the mechanical pickup head was redesigned with lower resonance than the traditional mica type. Also, a folded horn with an exponential taper was constructed inside the cabinet to provide better impedance matching to the air. As a result, playback of an Orthophonic record sounded like it was coming from a radio.

Eventually, when it was more common for electric recordings to be played back electrically in the 1930s and '40s, the overall tone was much like listening to a radio of the era. Magnetic pickups became more common and were better designed as time went on to dampen spurious resonances. Crystal pickups were also introduced as lower cost alternatives. The dynamic or moving coil microphone was introduced around 1930 and the velocity or ribbon microphone in 1932. Both of these high quality microphones became widespread in motion picture, radio, recording, and public address applications.

Over time, fidelity, dynamic and noise levels improved to the point that it was harder to tell the difference between a live performance in the studio and the recorded version. This was especially true after the invention of the variable reluctance magnetic pickup cartridge by General Electric in the 1940s when high quality cuts were played on well-designed audio systems. The Capehart radio/phonographs of the era with large diameter electrodynamic loudspeakers, though not ideal, demonstrated this quite well with "home recordings" readily available in the music stores for the public to buy.

There were important quality advances in recordings specifically made for radio broadcast. In the early 1930s Bell Telephone Laboratories and Western Electric announced the total reinvention of disc recording: the Western Electric Wide Range System, "The New Voice of Action." The intent of the new W. E. system was to improve the overall quality of disc recording and playback. The recording speed was 33⅓ rpm, originally used in the Western Electric/ERPI movie audio disc system implemented in the early Warner Brothers' Vitaphone "talkies" of 1927.

The newly invented W. E. moving coil or dynamic microphone was part of the Wide Range System. It had a flatter audio response than the old style Wente condenser type and didn't require electronics installed in the microphone housing. Signals fed to the cutting head were pre-emphasized in the treble region to help override noise in playback. Groove cuts in the vertical plane were employed rather than the usual lateral cuts. The chief advantage claimed was more grooves per inch which could be crowded together resulting in longer playback time. Additionally, the problem of inner groove distortion which plagued lateral cuts could be avoided with the vertical cut system. Wax masters were made by flowing heated wax over a hot metal disc thus avoiding the microscopic irregularities of cast blocks of wax and the necessity of planing and polishing.

Vinyl pressings were made with stampers from master cuts that were electroplated in vacuo by means of gold sputtering. Audio response was claimed out to 8,000 Hz, later 13,000 Hz, using light weight pickups employing jeweled styli. Amplifiers and cutters both using negative feedback were employed thereby improving the range of frequencies cut and lowering distortion levels. Radio transcription producers such as World Broadcasting System and Associated Music Publishers (AMP) were the dominant licensees of the W. E. wide range system and towards the end of the 1930s were responsible for two thirds of the total radio transcription business. A quantum level of improvement had been achieved, and when these recordings are found today in good condition, it is amazing to hear what high fidelity sound was like in that era. Playback of these recordings works well using a bass turnover of 300 Hz and a 10,000 Hz rolloff of −8.5 dB.

new speeds

In 1931, RCA Victor (which evolved from the Johnson and Berliner's Victor Talking Machine Company) launched the first commercially available vinyl long-playing record, marketed as "Program Transcription" discs. These revolutionary discs were designed for playback at 33⅓ rpm and pressed on a 30 cm diameter flexible plastic disc, with a duration of about ten minutes playing time per side. In Roland Gelatt's book The Fabulous Phonograph, the author notes that RCA Victor's early introduction of a long-play disc was a commercial failure for several reasons including the lack of affordable, reliable consumer playback equipment and consumer wariness during the Great Depression.^[10] Because of financial hardships that plagued the recording industry during that period (and RCA's own parched revenues), Victor's "long playing" records were quietly discontinued by early 1933.

There was also a small batch of "longer playing" records issued in the very early 1930s: Columbia introduced 10" 'longer playing' records (18000-D series), as well as a series of double-grooved or longer playing 10" records on their Harmony, Clarion & Velvet Tone cheap labels. All of these were phased out in mid-1932.

As recording technology evolved, more specific terms for various types of phonograph records were used in order to describe some aspect of the record: either its correct rotational speed ("16⅔ rpm" (revolutions per minute), "33⅓ rpm", "45 rpm", "78 rpm") or the material used (particularly "vinyl" to refer to records made of polyvinyl chloride, or the earlier "shellac records" generally the main ingredient in 78s). Other terms such as "Long Play" or LP and "Extended Play" or EP describe multi-track records that play a lot longer than the single-item-per-side records, which typically do not go much past 4 minutes per side. An LP can play for about thirty minutes per side. The 7" 45 rpm format normally contains one item per side but a 7" EP could achieve recording times of 10 to 15 minutes at the expense of attenuating and compressing the sound to reduce the width required by the groove. EP discs were generally used to make available tracks not on singles including tracks on LPs albums in a smaller, less expensive format for those who had only 45 rpm players. The large center hole on 7" 45 rpm records allows for easier handling by jukebox mechanisms. The term "album," originally used to mean a "book" with liner notes, holding several 78 rpm records each in its own "page" or sleeve, no longer has any relation to the physical format: a single LP record, or nowadays more typically a compact disc.

After World War II, two new competing formats came on to the market and gradually replaced the standard "78": the 33⅓ rpm (often just referred to as the 33 rpm), and the 45 rpm (see above). The 33⅓ rpm LP (for "long play") format was developed by Columbia Records and marketed in 1948. RCA Victor developed the 45 rpm format and marketed it in 1949, in response to Columbia.^[11] Both types of new disc used narrower grooves, intended to be played with smaller stylus—typically 0.001 inches (25 µm) wide, compared to 0.003 inches (76 µm) for a 78—so the new records were sometimes called Microgroove. In the mid-1950s all record companies agreed to a common recording standard called RIAA equalization. Prior to the establishment of the standard each company used its own preferred standard, requiring discriminating listeners to use pre-amplifiers with multiple selectable equalization curves.

A number of recordings were pressed at 16⅔ rpm (usually a 7-inch disc, visually identical to a 45 rpm single). Peter Goldmark, the man who developed the 33⅓ rpm record, developed the Highway Hi-Fi 16⅔ rpm record to be played in Chrysler automobiles, but poor performance of the system and weak implementation by Chrysler and Columbia led to the demise of the 16⅔ rpm records. Subsequently, the 16⅔ rpm speed was used for radio transcription discs or narrated publications for the blind and visually impaired, and were never widely commercially available, although it was common to see new turntable models with a 16 rpm speed setting produced as late as the 1970s.

The older 78 format continued to be mass produced alongside the newer formats until about 1960 in the U.S., and in a few countries, such as India (where some Beatles recordings were issued on 78), into the 1960s. For example, Columbia Records' last reissue of Frank Sinatra songs on 78 rpm records was an album called "Young at Heart", issued November 1, 1954.^[12] As late as the 1970s, some children's records were released at the 78 rpm speed. In the United Kingdom, the 78 rpm single lasted longer than in the United States and the 45 rpm took longer to become popular. The 78 rpm was overtaken in popularity by the 45 rpm in the late 1950s, as teenagers became increasingly affluent, although some of Elvis Presley's early singles sold more copies on 78 than on 45. The last new 78 rpm singles in the UK were released in March 1960 and production ceased in 1961.

The commercial rivalry between RCA Victor and Columbia Records led to RCA Victor's introduction of what it had intended to be a competing vinyl format, the 7-inch (175 mm) 45 rpm disc. For a two-year period from 1948 to 1950, record companies and consumers faced uncertainty over which of these formats would ultimately prevail in what was known as the "War of the Speeds". (See also format war.) In 1949 Capitol and Decca adopted the new LP format and RCA gave in and issued its first LP in January 1950. The 45 rpm size was gaining in popularity, too, and Columbia issued its first 45s in February 1951. By 1954, 200 million 45s had been sold.^[13]

Eventually the 12-inch (300 mm) 33⅓ rpm LP prevailed as the predominant format for musical albums and 10" LPs were no longer issued. The last Columbia Records reissue of any Frank Sinatra songs on a 10" LP record was an album called "Hall of Fame", CL 2600, issued October 26, 1956, containing six songs, one each by Tony Bennett, Rosemary Clooney, Johnny Ray, Frank Sinatra, Doris Day, and Frankie Laine.^[12] The 10" LP however had a longer life in the United Kingdom, where important early British rock and roll albums such as Lonnie Donegan's Lonnie Donegan Showcase and Billy Fury's The Sound of Fury were released in that form. The 7-inch (175 mm) 45 rpm disc or "single" established a significant niche for shorter duration discs, typically containing one item on each side. The 45 rpm discs typically emulated the playing time of the former 78 rpm discs, while the 12" LP discs provided up to one half hour of time per side. The amount of music per LP varied from label to label and possibly from performer to performer. Frank Sinatra's "A Swinging Affair", a monaural album, contained 15 songs and ran 50 minutes. Other albums by other performers could run as little as 30 or 35 minutes. After the introduction of stereophonic recording, record times dropped because, presumably, the early stereo groove was wider than the monaural groove.

thumb|right|150px|A stroboscopic disc for 33⅓ and 45 rpm (actually 44.77 rpm as it has the wrong number of segments on the 45 ring) at 50 Hz

The 45 rpm discs also came in a variety known as extended play (EP) which achieved up to 10–15 minutes play at the expense of attenuating (and possibly compressing) the sound to reduce the width required by the groove. EP discs were generally used to reissue LP albums on the smaller format for those people who had only 45 rpm players. LP albums could be purchased 1 EP at a time, with four items per EP, or in a boxed set with 3 EPs or 12 items. The large center hole on 45s allows for easier handling by jukebox mechanisms. EPs were generally discontinued by the late 1950s as three- and four-speed record players replaced the individual 45 players. One indication of the decline of the 45 rpm EP is that the last Columbia Records reissue of Frank Sinatra songs on 45 rpm EP records, called "Frank Sinatra" (Columbia B-2641) was issued December 7, 1959.^[12] However, the EP lasted considerably longer in Europe, and was a popular format during the 1960s for recordings by artists such as Serge Gainsbourg and the Beatles.

In the late 1940s and early 1950s, 45 rpm-only players that lacked speakers and plugged into a jack on the back of a radio were widely available. Eventually, they were replaced by the three–speed record player.

From the mid-1950s through the 1960s, in the U.S. the common home "record player" or "stereo" (after the introduction of stereo recording) would typically have had these features: a three- or four-speed player (78, 45, 33⅓, and sometimes 16⅔ rpm); with changer, a tall spindle that would hold several records and automatically drop a new record on top of the previous one when it had finished playing, a combination cartridge with both 78 and microgroove styli and a way to flip between the two; and some kind of adapter for playing the 45s with their larger center hole. The adapter could be a small solid circle that fit onto the bottom of the spindle (meaning only one 45 could be played at a time) or a larger adaptor that fit over the entire spindle, permitting a stack of 45s to be played.^[14]

RCA 45s were also adapted to the smaller spindle of an LP player with a plastic snap-in insert known as a "spider".^[14] These inserts, commissioned by RCA president David Sarnoff and invented by Thomas Hutchison,^[15] were prevalent starting in the 1960s, selling in the tens of millions per year during the 45 rpm heyday. In countries outside of the U.S., 45s often had the smaller album-sized holes, e.g., Australia and New Zealand, or otherwise a pseudo-spider was "built-in" to the record, which could be punched out, if desired, i.e., the United Kingdom, especially before the 1970s.

In the 1890s, the early recording formats of discs were usually seven inches (nominally 17.5 cm) in diameter. By 1910 the 10-inch (25.4 cm) record was by far the most popular standard, holding about three minutes of music or entertainment on a side. From 1903 onwards, 12-inch records (30.5 cm) were also sold commercially, mostly of classical music or operatic selections, with four to five minutes of music per side. (Victor, Brunswick and Columbia also issued 12" popular medleys, usually spotlighting a Broadway show score.) However, other sizes did appear. 8 inch discs with a 2 inch diameter label became popular for about a decade in Britain, but they cannot be played in full on most modern record players because the one arm can't reach far enough without modification to the equipment.

The playing time of a phonograph record depended on the turntable speed and the groove spacing. At the beginning of the 20th century, the early discs played for two minutes, the same as early cylinder records.^[16] The 12-inch disc, introduced by Victor in 1903, increased the playing time to three and a half minutes.^[17] Because a 10-inch 78 rpm record could hold about three minutes of sound per side and the 10-inch size was the standard size for popular music, almost all popular recordings were limited to around three minutes in length.

For example, when King Oliver's Creole Jazz Band, including Louis Armstrong on his first recordings, recorded 13 sides at Gennett Records in Richmond, Indiana, in 1923, one side was 2:09 and four sides were 2:52–2:59.^[18]

By 1938, when Milt Gabler started recording on January 17 for his new label, Commodore Records, to allow longer continuous performances, he recorded some 12" records. Eddie Condon explained: "Gabler realized that a jam session needs room for development." The first two 12" recordings did not take advantage of the extra length: "Carnegie Drag" was 3:15; "Carnegie Jump", 2:41. But, at the second session, on April 30, the two 12" recordings were longer: "Embraceable You" was 4:05; "Serenade to a Shylock", 4:32.^[19]^[20]

Another way around the time limitation was to issue a selection on both sides of a single record. Vaudeville stars Gallagher and Shean, recorded "Mr. Gallagher and Mr. Shean", written by Irving and Jack Kaufman, as two-sides of a 10" 78 in 1922 for Cameo.^[21]

An obvious workaround for longer recordings was to release a set of records. The first multi-record release was in 1903, when HMV in England made the first complete recording of an opera, Verdi's Ernani, on 40 single-sided discs.^[22] In 1940, Commodore released Eddie Condon and his Band's recording of "A Good Man Is Hard to Find" in four parts, issued on both sides of two 12" 78s.

This limitation on the length of both popular-music and jazz numbers persisted from 1910 until the invention of the LP, in 1948.

In popular music, this time limitation of about 3:30 on a 10" 78 rpm record meant that singers usually did not release long pieces on record. One exception is Frank Sinatra's recording of Rodgers and Hammerstein's "Soliloquy", from Carousel, made on May 28, 1946. Because it ran 7:57, longer than both sides of a standard 78 rpm 10" record, it was released on Columbia's Masterwork label (the classical division) as two sides of a 12" record. (See date.)

In the 78 era, classical-music and spoken-word items generally were released on the longer 12" 78s, about 4–5 minutes per side. For example, on June 10, 1924, four months after the February 12 premier of Rhapsody in Blue, George Gershwin recorded it with Paul Whiteman and His Orchestra. It was released on two sides of Victor 55225 and runs 8:59. Look under the title

High fidelity

The first of these was the attempt to develop high fidelity, or hi-fi, sound.

In the late 1920s and early 1930s, since vertical modulation was considered the higher fidelity medium due to its immunity of picking up common lateral turntable rumble, caused by the rubber puck driving the edge of the turntable rim, an earlier version of the Cook binaural system (described below in Stereo) was experimented with as well, but for high-fidelity, not for stereo (at least not yet).

This system utilized vertical modulation in the smaller space near the center of the disc for the bass portion of the program, starting from halfway through the disc going to the label avoiding inner-groove distortion, and used lateral modulation for the treble portion of the program in the larger space from the edge of the disc to halfway through for the treble portion of the program. This meant that the lateral turntable rumble could be filtered out of the treble electronically by a crossover network and the crackle and static of the treble could be filtered out of the bass by the same process.^{[citation needed]}

Since vertical pickups were harder to come by and took up more space than their lateral counterparts, experiments were soon underway to record both the bass and the treble portions of a high-fidelity program in their own separate grooves in a lateral fashion on the same side of the disc. Utilizing a two-channel amplifier and speaker system, with one channel driving the wide-range woofer, and one channel driving the combination wide-range midrange and tweeter, true wide-range high-fidelity would be achieved. The format was only experimental, but it wasn't long before this system was adapted once again for early stereo (see below).

People who were concerned with hearing all the quality sound now embedded in the new LPs began to buy separate turntables, amplifiers, speakers and woofers to get the best sound possible.

Stan Freberg satirized these fans in his 1956 radio show with a skit about a man who turned his whole house into a speaker.
Flanders & Swann also poked fun at installing the components necessary for high fidelity in their Song of Reproduction.

(In 1931, Victor experimented with a high-fidelity microphone recording system and a number of records issued in the 22900 and 24000 series were surprisingly "hi-fi." However, the records were too loud and 'blasty' on most home reproducers, and after getting complaints from their dealers, Victor stopped using this equipment in their New York and Camden studios around mid-1932 and sent it to their Chicago studio, where it continued to be used until about 1934.)

In 1957 the first commercial stereo two-channel records were issued on translucent blue vinyl by Bel Canto, the first of which is a highly-collectible multi-colored-vinyl sampler featuring `A Stereophonic Tour of Los Angeles' narrated by Jack Wagner on one side, and a collection of tracks from various Bel Canto albums on the back.^{[citation needed]}

Following in 1958, more Stereo LP releases were offered by Audio Fidelity in the USA and Pye in Britain, using the Westrex "45/45" single-groove system.

some stuff

1. Electrical transcriptions and 78s were first used as sources to master LP lacquer/aluminum cuts in 1948. This was before magnetic tape was commonly employed for mastering. Variable pitch groove spacing helped enable greater recorded dynamic levels. The heated stylus improved the cutting of high frequencies. Gold sputtering in vacuo became increasingly used to make high quality matrices from the cuts to stamp vinyl records.
2. Decca in England employed high quality wide range microphones (condensers) for the Full Frequency Range Recording (FFRR) system ca. 1949. Wax mastering was employed to produce Decca/London LPs. This created quite a bit of interest in the United States and raised overall quality expectations by customers for microgroove records.
3. Tape recording with condenser microphones became a long used standard operating procedure in mastering lacquer/aluminum cuts. This improved the overall pickup of high quality sound and enabled tape editing. Over the years there were variations in the kinds of tape recorders used such as the width and number of tracks employed, including 35 mm magnetic film technology.
4. Production of stereo tape masters and the stereo LP in 1958 were quantum level improvements in recording technology.
5. Limitations in the disc cutting part of the process later generated the idea that half-speed mastering would improve quality (in which the source tape is played at half-speed and the lacquer/aluminum disc cut at 16⅔ rpm rather than 33⅓ rpm).
6. Some 12 inch LPs were cut at 45 rpm claiming better quality sound, but this practice was short-lived.
7. Efforts were made in the 1970s to record as many as four audio channels on an LP ("Quadraphonic") by means of matrix and modulated carrier methods. This development, though another quantum level improvement, was neither a widespread success nor long lasting.
8. There were approaches to simplify the chain of equipment in the recording process and return to live recording directly to the disc master.
9. Some records were produced employing noise reduction systems in the tape mastering as well as in the LP itself.
10. As video recorders became perfected technically it became possible to modify them and use analog to digital converters (codecs) for digital sound recording. This enabled tape mastering with greater dynamic range, low noise and distortion, and freedom from drop outs as well as pre- and post-echo. The digital recording was played back providing a high quality analog signal to master the lacquer/aluminum cut.

packaging / origin of the album

Such 78 rpm records were usually sold separately, in brown paper or cardboard sleeves that were sometimes plain and sometimes printed to show the producer or the retailer's name. Generally the sleeves had a circular cut-out allowing the record label to be seen. Records could be laid on a shelf horizontally or stood upright on an edge, but because of their fragility, many broke in storage.

German record company Odeon is often said to have pioneered the "album" in 1909 when it released the "Nutcracker Suite" by Tchaikovsky on 4 double-sided discs in a specially-designed package. [1] (It is not indicated what size the records are.) However, Deutsche Grammophon had produced an album for its complete recording of the opera Carmen in the previous year. The practice of issuing albums does not seem to have been widely taken up by other record companies for many years; however, HMV provided an album, with a pictorial cover, for the 1917 recording of The Mikado (Gilbert & Sullivan).

By about 1910^{[note 1]} bound collections of empty sleeves with a paperboard or leather cover, similar to a photograph album, were sold as "record albums" that customers could use to store their records (the term "record album" was printed on some covers). These albums came in both 10" and 12" sizes. The covers of these bound books were wider and taller than the records inside, allowing the record album to be placed on a shelf upright, like a book, suspending the fragile records above the shelf and protecting them.

Starting in the 1930s, record companies began issuing collections of 78 rpm records by one performer or of one type of music in specially assembled albums, typically with artwork on the front cover and liner notes on the back or inside cover. Most albums included 3 or 4 records, with 2 sides each, making 6 or 8 songs per album. When the 12-inch vinyl LP era began in 1949, the single record often had the same or similar number of songs as a typical album of 78s, which gave rise to the tradition of the term "album" being given to the LP.

Developmentally, much of the technology of the long playing record, successfully released by Columbia in 1948, came from wide range radio transcription practices. The use of vinyl pressings, increased length of programming, and general improvement in audio quality over 78 rpm records were the major selling points.

The complete technical disclosure of the Columbia LP by Peter C. Goldmark, Rene' Snepvangers and William S. Bachman in 1949 made it possible for a great variety of record companies to get into the business of making long playing records. The business grew like "wild fire" as did the widespread interest in high fidelity sound and the do-it-yourself market for pickups, turntables, amplifier kits, loudspeaker enclosure plans, and AM/FM radio tuners. The LP record for longer works, 45 rpm for pop music, and FM radio became high fidelity program sources in demand. Radio listeners heard recordings broadcasted and this in turn generated more record sales. The industry flourished.

Other enhancements

Under the direction of recording engineer C. Robert Fine, Mercury Records initiated a minimalist single microphone monaural recording technique in 1951. The first record, a Chicago Symphony Orchestra performance of "Pictures at an Exhibition," conducted by Rafael Kubelik, was described as "being in the living presence of the orchestra" by The New York Times music critic. The series of records was then named “Mercury Living Presence.” In 1955, Mercury began three-channel stereo recordings, still based on the principle of the single microphone. The center (single) microphone was of paramount importance, with the two side mics adding depth and space. Record masters were cut directly from a three-track to two-track mixdown console, with all editing of the master tapes done on the original three-tracks. In 1961, Mercury enhanced this technique with three-microphone stereo recordings using 35 mm magnetic film instead of half-inch tape for recording. The greater thickness and width of 35 mm magnetic film prevented tape layer print-through and pre-echo and gained extended frequency range and transient response. The Mercury Living Presence recordings were remastered to CD in the 1990s by the original producer, Wilma Cozart Fine, using the same method of 3-to-2 mix directly to the master recorder.

The development of quadraphonic records was announced in 1971. These recorded four separate sound signals. This was achieved on the two stereo channels by electronic matrixing, where the additional channels were combined into the main signal. When the records were played, phase-detection circuits in the amplifiers were able to decode the signals into four separate channels. There were two main systems of matrixed quadraphonic records produced, confusingly named SQ (by CBS) and QS (by Sansui). They proved commercially unsuccessful, but were an important precursor to later "surround sound" systems, as seen in SACD and home cinema today. A different format, CD-4 (not to be confused with compact disc), by RCA, encoded rear channel information on an ultrasonic carrier, which required a special wideband cartridge to capture it on carefully calibrated pickup arm/turntable combinations. Typically the high-frequency information inscribed onto these LPs wore off after only a few playings, and CD-4 was even less successful than the two matrixed formats. (A further problem was that no cutting heads were available that could handle the HF information. That was remedied by cutting at 'half-speed.' Later, the special half-speed cutting heads and equalization techniques were employed to get a wider frequency response in stereo with reduced distortion and greater headroom.)

Through the 1960s, 1970s, and 1980s, various methods to improve the dynamic range of mass produced records involved highly advanced disc cutting equipment. These techniques, marketed, to name two, as the CBS DisComputer and Teldec Direct Metal Mastering, were used to reduce inner-groove distortion. RCA Victor introduced another system to reduce dynamic range and achieve a groove with less surface noise under the commercial name of Dynagroove. Two main elements were combined: another disk material with less surface noise in the groove and dynamic compression for masking background noise. Sometimes this was called "diaphragming" the source material and not favoured by some music lovers for its unnatural side effects. Both elements were reflected in the brandname of Dynagroove, described elsewhere in more detail. It also used the earlier advanced method of forward-looking control on groove spacing with respect to volume of sound and position on the disk. Lower recorded volume used closer spacing; higher recorded volume used wider spacing, especially with lower frequencies. Also, the higher track density at lower volumes enabled disk recordings to end farther away from the disk center than usual, helping to reduce endtrack distortion even further.

Also in the late 1970s, "direct-to-disc" records were produced, aimed at an audiophile niche market. These completely bypassed the use of magnetic tape in favor of a "purist" transcription directly to the master lacquer disc. Also during this period, "half-speed mastered" and "original master" records were released, using expensive state-of-the-art technology. A further late 1970s development was the Disco Eye-Cued system used mainly on Motown 12-inch singles released between 1978 and 1980. The introduction, drum-breaks, or choruses of a track were indicated by widely separated grooves, giving a visual cue to DJs mixing the records. The appearance of these records is similar to an LP, but they only contain one track each side.

The early 1980s saw the introduction of "dbx-encoded" records, again for the audiophile niche market. These were completely incompatible with standard record playback preamplifiers, relying on the dbx compandor encoding/decoding scheme to greatly increase dynamic range (dbx encoded disks were recorded with the dynamic range compressed by a factor of two in dB: quiet sounds were meant to be played back at low gain and loud sounds were meant to be played back at high gain, via automatic gain control in the playback equipment; this reduced the effect of surface noise on quiet passages). A similar and very short-lived scheme involved using the CBS-developed "CX" noise reduction encoding/decoding scheme.

Laser turntable

ELPJ, a Japanese-based company, sells a laser turntable that uses a laser to read vinyl discs optically, without physical contact. The laser turntable eliminates record wear and the possibility of accidental scratches, which degrade the sound, but its expense limits use primarily to digital archiving of analog records; and the laser does not recognize colored vinyl or picture disks. Various other laser-based turntables were tried during the 1990s, but while a laser reads the groove very accurately, since it does not touch the record the dust that vinyl attracts due to static electric charge is not mechanically pushed out of the groove, worsening sound quality in casual use compared to conventional stylus playback.

In some ways similar to the laser turntable is the IRENE scanning machine for disc records, which images with microphotography in two dimensions, invented by a team of physicists at Lawrence Berkeley Laboratories. IRENE will retrieve the information from a laterally-modulated monaural grooved sound source without touching the media itself, but cannot read vertically-modulated information. This excludes grooved recordings such as cylinders and some radio transcriptions which feature a hill-and-dale format of recording, and stereophonic or quadraphonic grooved recordings which utilize a combination of the two as well as supersonic encoding for quadraphonic.

An offshoot of IRENE, the Confocal Microscope Cylinder Project, can capture a high-resolution 3-D image of the surface, down to 200 µm. In order to convert to a digital sound file, this is then played by a version of the same 'virtual stylus' program developed by the research team in real-time, converted to digital and, if desired, processed through sound-restoration programs.

Before final playback in the computer to convert to digital audio files in real-time, it is possible to remove many of the sonic imperfections in the media while still in the video domain, by utilizing the same tools as major motion picture studios in restoring their films.^{[citation needed]}

The normal commercial disc is engraved with two sound-bearing concentric spiral grooves, one on each side, running from the outside edge towards the centre. The last part of the spiral meets an earlier part to form a circle. The sound is encoded by fine variations in the edges of the groove that cause a stylus (needle) placed in it to vibrate at acoustic frequencies when the disc is rotated at the correct speed. Generally, the outer and inner parts of the groove bear no intended sound (an exception is Split Enz's Mental Notes).

Since the late 1910s, both sides of the record have been used to carry the grooves. Occasionally, records were issued in the 1920s with a recording on only one side. In the eighties Columbia records briefly issued a series of less expensive one-sided 45 rpm singles.

LP versus CD

In the early days of compact discs, vinyl records were still prized by audiophiles because of better reproduction of analog recordings; however, the drawback was greater sensitivity to scratches and dust. Early compact discs were perceived by many as thin and sharp—distorting sounds on the high end. In some cases, this was the result of record companies issuing CDs produced from master recordings that were compressed and equalized for cutting. Early consumer compact disc players sometimes contained 14-bit digital-to-analog converters, instead of the correct 16-bit type, as a cost-cutting measure. Some players were only linear to 10 or 12 bits.^[23]

Though digital audio technology has improved over the years, some audiophiles still prefer what they perceive as the superior sound of vinyl over CDs.

Proponents of digital audio state these differences are generally inaudible to normal human hearing, and the lack of clicks, hiss and pops from analog recordings greatly improves sound fidelity. Modern anti-aliasing filters and oversampling systems used in digital recordings have reduced the problems observed with early CDs.

The "warmer" sound of analog records is generally believed on both sides of the argument to be an artifact of harmonic distortion and signal compression. This phenomenon of a preference for the sound of a beloved lower-fidelity technology is not new; a 1963 review of RCA Dynagroove recordings notes that "some listeners object to the ultra-smooth sound as ... sterile ... such distortion-forming sounds as those produced by loud brasses are eliminated at the expense of fidelity. They prefer for a climactic fortissimo to blast their machines ..."

The theory that vinyl records can audibly represent lower frequencies that compact discs cannot (making the recording sound "warmer") is disputed by some and accepted by others. According to Red Book specifications, the compact disc has a frequency response up to 22,050 Hz. The average human auditory system is sensitive to frequencies from 20 Hz to a maximum of around 20,000 Hz.^[24] The upper and lower frequency limits of human hearing vary per person.

Current status

Groove recordings, first designed in the final quarter of the 19th century, held a predominant position for nearly a century—withstanding competition from reel-to-reel tape, the 8-track cartridge and the compact cassette. However, in 1988, the compact disc surpassed the gramophone record in popularity. Vinyl records experienced a sudden decline in popularity between 1988 and 1991,^[25] when the major label distributors restricted their return policies, which retailers had been relying on to maintain and swap out stocks of relatively unpopular titles. First the distributors began charging retailers more for new product if they returned unsold vinyl, and then they stopped providing any credit at all for returns. Retailers, fearing they would be stuck with anything they ordered, only ordered proven, popular titles that they knew would sell, and devoted more shelf space to CDs and cassettes. Record companies also deleted many vinyl titles from production & distribution, further undermining the availability of the format and leading to the closure of pressing plants. This rapid decline in the availability of records accelerated the format's decline in popularity, and is seen by some as a deliberate ploy to make consumers switch to CDs, which were more profitable for the record companies.^[26]^[27]^[28]^[29]

In spite of their flaws, such as the lack of portability, records still have enthusiastic supporters. Vinyl records continue to be manufactured and sold today, especially by independent rock bands and labels, although record sales are considered to be a niche market composed of audiophiles, collectors and DJs. Old records and out of print recordings in particular are in much demand by collectors the world over. (See Record collecting.) Many popular new albums are given releases on vinyl records and older albums are also given reissues as well, sometimes on audiophile grade vinyl with high quality sleeves.

In the United Kingdom, sales of new vinyl records (particularly 7 inch singles) have increased significantly in recent years,^[30]^[31] somewhat reversing the downward trend seen during the 1990s.

In the United States, annual vinyl sales increased by 85.8% between 2006 and 2007,^[32] and by 89% between 2007 and 2008.^[33]

Many electronic dance music and hip hop releases today are still exclusively on vinyl. This is because for disc jockeys ("DJs"), vinyl has an advantage over the CD: direct manipulation of the medium. DJ techniques such as slip-cueing, beatmatching and scratching originated on turntables. With CDs or compact audio cassettes one normally has only indirect manipulation options, e.g., the play, stop and pause buttons. With a record one can place the stylus a few grooves farther in or out, accelerate or decelerate the turntable, or even reverse its direction, provided the stylus, record player, and record itself are built to withstand it. However, many CDJ and DJ advances, such as DJ software and time-encoded vinyl, now have these capabilities and more.

Vinyl is also more and more popular in other musical genres such as hardcore punk, alt-metal or indie rock. Limited vinyl editions of new albums or EPs are prized by fans even though the music is not related in any way to DJing or audiophiles.

Figures released in the United States in early 2009 showed that sales of vinyl albums nearly doubled in 2008, with 1.88 million sold - up from just under 1 million in 2007.^[34]

Formats

[[Immage:Schellackplatte 1908.jpg|thumb|175px|Record of Emile Berliner's Gramophone Company (later Deutsche Grammophon). Made 1908 in Hannover, Germany]]

Sizes of records in the US and the UK are generally measured in inches, usually represented with a double prime symbol, e.g., 7" (7-inch) records, which are generally 45 rpm records. LPs were 10" records at first, but soon the 12" size became by far the most common, with 78s generally being 10", but also 12" and 7" and even smaller—the so called "little wonders".^[35]

Diameter	Revolutions per minute	Time duration
12 in. (30 cm)	33⅓ rpm	45 min Long play (LP)
12 in. (30 cm)	45 rpm	12-inch single, Maxi Single, and Extended play (EP)
10 in. (25 cm)	33⅓ rpm	Long play (LP)
10 in. (25 cm)	78 rpm	3 minutes
7 in. (17.5 cm)	45 rpm	Single, and Extended play (EP)
7 in. (17.5 cm)	33⅓ rpm	Often used for children's records in the 1960s and 1970s.

Less common formats

clv

At least one manufacturer, Philips, produced records that played at a constant linear velocity. As these were played from the inside to the outside, the rotational speed of the record reduced as reproduction progressed (as is also true of the modern Compact Disc).^[4]

The earliest rotation speeds varied widely. Most records made in 1900–1925 were recorded at 74–82 revolutions per minute (rpm). Edison Disc Records consistently ran at 80 rpm.

However a few unusual systems were deployed. The Dutch Philips company introduced records whose rotational speed varied such that the reproducing "needle" ran at a constant linear velocity (CLV) in the groove. These records, also unusually, played from the inside to the outside. Both of these features were later to be found in the modern day compact disc, which itself was also invented by Philips. The London Science Museum displays a Philips CLV record marked as "Speed D".^{[citation needed]}

[[Immage:45rpminsert.jpg|thumbnail|150px|right|Columbia and RCA's competition extended to equipment. Some turntables included spindle size adapters, but other turntables required snap-in inserts like this one to adapt RCA's larger 45 rpm spindle size to the smaller spindle size available on nearly all turntables.^[14] Shown is one popular design in use for many years.]]

strobic

While stroboscopic speed checkers can be used to correctly adjust a turntable speed to 45 rpm in the U.S. where the stroboscope disc is illuminated by a lamp run from a 60 Hz supply, most strobes are slightly inaccurate where there is a 50 Hz supply. Using a conventional single segment per pulse, the nearest that can be achieved is 45.112+ rpm, which requires a disc with 133 segments. The difference amounts to the record sounding sharp by about a twenty-fifth of a semitone, i.e., practically unnoticeable. To construct a 50 Hz stroboscope disc that appears stationary at exactly 45 rpm is possible, and would require 400 segments advancing by 3 segments on each pulse of light.

(Dividing the strobe frequency (100 Hz as the lamp lights every half-cycle) by the record speed in revolutions per second (0.75 rev/sec for a 45 rpm record) and stating the answer as an improper fraction gives the number of segments in the numerator and the number of segments advanced in the denominator. In the example above: 100 Hz x 4/3 = 400/3, 400 segments, advancing 3 segments on each pulse of light. Compare with 60 Hz: 120 Hz x 4/3 = 120 segments, 1 segment per pulse.)

thumb|left|175px|1959 Seeburg 16 rpm record

Seeburg Corporation introduced the Seeburg Background Music System in 1959, using a 16⅔ rpm 9-inch record with 2-inch center hole. Each record held 40 minutes of music per side, recorded at 420 grooves per inch.^[36]

Deliberately playing or recording records at a higher speed gave an antic quirkiness to voices; doing so at a slower speed changed music and voice to an ominous, growling tone. Canadian musician Nash the Slash also took advantage of this speed/tonal effect with his 1981 12-inch disc Decomposing, which featured four instrumental tracks that were engineered to play at any speed (with the playing times listed for 33⅓, 45 and 78 rpm playback). As for the speed-swapping novelty effect, a Tracey Ullman 45, played back at 33, sounds like Mick Jagger. A Jeff Lynne 33 track, played back at 45, sounds like Cyndi Lauper. Not only that, but listening to Switched-On Bach, at half-speed, allows one to deconstruct the recording and understand how it was accomplished.

thumb|right|A modern 12" vinyl album being played. Note the stylus's contact with the surface.

Both the microgroove LP 33⅓ rpm record and the 45 rpm single records are made from vinyl plastic that is flexible and unbreakable in normal use. However, the vinyl records are easier to scratch or gouge, and much more prone to warping.

Sound reproduction & materials

Equalization

Due to recording mastering and man ufacturing limitations, both high and low frequencies were removed from the first recorded signals by various formulae. With low frequencies, the stylus must swing a long way from side to side, requiring the groove to be wide, taking up more space and limiting the playing time of the record. At high frequencies noise is significant. These problems can be compensated for by using equalization to an agreed standard. This simply means reducing the amplitude at low-frequencies, thus reducing the groove width required, and increasing the amplitude at high frequencies. The playback equipment boosts bass and cuts treble in a complementary way. The result should be that the sound is perceived to be without change, thus more music will fit the record, and noise is reduced.

The agreed standard has been RIAA equalization since 1952, implemented in 1955. Prior to that, especially from 1940, some 100 formulae were used by the record manufacturers.

In 1926 it was disclosed by Joseph P. Maxwell and Henry C. Harrison from Bell Telephone Laboratories that the recording pattern of the Western Electric (W. E.) "rubber line" magnetic disc cutter had a constant velocity characteristic. This meant that as frequency increased in the treble, recording amplitude decreased. Conversely, in the bass as frequency decreased, recording amplitude increased. Therefore, it was necessary to attenuate the bass frequencies below about 250 Hz, the bass turnover point, in the amplified microphone signal fed to the recording head. Otherwise, bass modulation became excessive and overcutting took place into the next record groove. When played back electrically with a magnetic pickup having a smooth response in the bass region, a complementary boost in amplitude at the bass turnover point was necessary. G. H. Miller in 1934 reported that when complementary boost at the turnover point was used in radio broadcasts of records, the reproduction was more realistic and many of the musical instruments stood out in their true form.

West in 1930 and later P. G. H. Voight (1940) showed that the early Wente-style condenser microphones contributed to a 4 to 6 dB midrange brilliance or pre-emphasis in the recording chain. This meant that the electrical recording characteristics of W. E. licensees such as Columbia Records and Victor Talking Machine Company in the 1925 era had a higher amplitude in the midrange region. Brilliance such as this compensated for dullness in many early magnetic pickups having drooping midrange and treble response. As a result, this practice was the empirical beginning of using pre-emphasis above 1,000 Hz in 78 rpm and 33⅓ rpm records.

Over the years a variety of record equalization practices emerged and there was no industry standard. For example, in Europe recordings for years required playback with a bass turnover setting of 250–300 Hz and a treble rolloff at 10,000 Hz ranging from 0 to −5 dB or more. In the United States there were more varied practices and a tendency to use higher bass turnover frequencies such as 500 Hz as well as a greater treble rolloff like −8.5 dB and even more to record generally higher modulation levels on the record.

Evidence from the early technical literature concerning electrical recording suggests that it wasn't until the 1942–1949 period that there were serious efforts to standardize recording characteristics within an industry. Heretofore, electrical recording technology from company to company was considered a proprietary art all the way back to the 1925 W. E. licensed method used by Columbia and Victor. For example, what Brunswick-Balke-Collender (Brunswick Corporation) did was different from the practices of Victor.

Broadcasters were faced with having to adapt daily to the varied recording characteristics of many sources: various makers of "home recordings" readily available to the public, European recordings, lateral cut transcriptions, and vertical cut transcriptions. Efforts were started in 1942 to standardize within the National Association of Broadcasters (NAB), later known as the National Association of Radio and Television Broadcasters (NARTB). The NAB, among other items, issued recording standards in 1949 for laterally and vertically cut records, principally transcriptions. A number of 78 rpm record producers as well as early LP makers also cut their records to the NAB/NARTB lateral standard.

The lateral cut NAB curve was remarkably similar to the NBC Orthacoustic curve which evolved from practices within the National Broadcasting Company since the mid-1930s. Empirically, and not by any formula, it was learned that the bass end of the audio spectrum below 100 Hz could be boosted somewhat to override system hum and turntable rumble noises. Likewise at the treble end beginning at 1,000 Hz, if audio frequencies were boosted by 16 dB at 10,000 Hz the delicate sibilant sounds of speech and high overtones of musical instruments could survive the noise level of cellulose acetate, lacquer/aluminum, and vinyl disc media. When the record was played back using a complementary inverse curve, signal to noise ratio was improved and the programming sounded more life-like.

When the Columbia LP was released in June 1948, the developers subsequently published technical information about the 33⅓ rpm microgroove long playing record. Columbia disclosed a recording characteristic showing that it was like the NAB curve in the treble, but had more bass boost or pre-emphasis below 200 Hz. The authors disclosed electrical network characteristics for the Columbia LP curve. This was the first such curve based on formulae.

In 1951 at the beginning of the post-World War II high fidelity (hi-fi) popularity, the Audio Engineering Society (AES) developed a standard playback curve. This was intended for use by hi-fi amplifier manufacturers. If records were engineered to sound good on hi-fi amplifiers using the AES curve, this would be a worthy goal towards standardization. This curve was defined by the time constants of audio filters and had a bass turnover of 400 Hz and a 10,000 Hz rolloff of −12 dB.

RCA Victor and Columbia were in a "market war" concerning which recorded format was going to win: the Columbia LP versus the RCA Victor 45 rpm disc (released in February 1949). Besides also being a battle of disc size and record speed, there was a technical difference in the recording characteristics. RCA Victor was using "New Orthophonic" whereas Columbia was using the LP curve.

Ultimately, the New Orthophonic curve was disclosed in a publication by R. C. Moyer of RCA Victor in 1953. He traced RCA Victor characteristics back to the W. E. "rubber line" recorder in 1925 up to the early 1950s laying claim to long-held recording practices and reasons for major changes in the intervening years. The RCA Victor New Orthophonic curve was within the tolerances for the NAB/NARTB, Columbia LP, and AES curves. It eventually became the technical predecessor to the RIAA curve.

As the RIAA curve was essentially an American standard, it had little impact outside of the USA until the late 1970s when European recording labels began to adopt the RIAA equalization. It was even later when some Asian recording labels adopted the RIAA standard.

In 1989, many Eastern European recording labels and Russian recording labels such as Melodiya were still using their own CCIR equalization. Hence the RIAA curve only truly become a global standardization not until late the 1980s.

Further, even after officially agreeing to implement the RIAA equalization curve, many recording labels continued to use their own proprietary equalization even well into the 1970s. Columbia is one such prominent example in the USA, as are Decca, Teldec and Deutsche Grammophon in Europe. To further cloud the picture, some labels even saw different equalization curves arise from differently located pressing plants.

To further complicate matters, identical equalization curves existed but were named differently by different recording labels. Some small recording labels advertised their special curves which were the same as Columbia/RCA Ortophonic curves.

While the stylus moves horizontally when reproducing a monophonic disk recording, on stereo records the stylus moves vertically as well as horizontally. In fact, prior to the full development of the 45/45 system, the first stereo cutting heads were made by bolting together one lateral cut head and one vertical cut head sharing a common stylus holder. Feeding the driving coils with suitably phased material, a practice which would later give rise to the matrices used in quadraphony, achieved the 45/45 groove.

[[Immage:Plattenschrift en.svg|thumb|rill with sound only on left channel]]

One could envision a system in which the left channel was recorded laterally, as on a monophonic recording, with the right channel information recorded with a "hill-and-dale" vertical motion; such systems were proposed but not adopted, due to their incompatibility with existing phono pickup designs (see below). Prior to these experiments, the lateral and vertical portions of the groove were experimented with in a discrete twin-groove system described below.

However, before this lateral-vertical single-groove system was experimented with for stereo reproduction, its components were adopted for other uses, namely many radio station music transcriptions used the vertical modulation portion with its higher fidelity and lower susceptibility to rumble, and lateral portion for speech, as the rumble could be filtered out electronically and not affect the program.

Also by the mid-1950s, an audio engineer by the name of Mintner grew tired of the incompatibility of the vertical portion of stereo records and their susceptibility of damage when played with a mono vertically-noncompliant cartridge and stylus and came up with a way to have both channels recorded laterally and in the same groove.

Due to the frequency limitations of cutting heads of the period, the disc needed to be mastered at 16-2/3 RPM for playback at 33-1/3 RPM, a practice which would later be adapted and improved in the 1970s, coupled with 180 gram virgin vinyl to create Half Speed Mastered audiophile LPs.

Similar to lateral-vertical stereo played through a 45/45 stereo system, Mintner left the normal mono signal in the normal frequency range of 20Hz-20KHz, ensuring compatibility with normal mono players of the period, and then moved the difference signal up to a supersonic band of 20KHz-45KHz by modulating a 30KHz carrier signal engraved on the disc. A carrier detector and de-matrix circuit, similar to what would later be used for FM multiplex stereo, sensed the carrier wave, stripped it off, retrieved the signal, and then matrixed it with the original mono signal to create stereo.

Unfortunately, the development of lightweight pickup arms was still many years away, so the heavy weight of pickup arms in the 1950s caused the carrier wave on the record to be completely destroyed after only a few plays. But, both the modulated carrier wave and matrix-encoding systems used herein would later be multiplied by two and used as CD-4 and SQ/QS respectively in quadraphonic.^{[citation needed]}

Another early-stereo experiment engraved the left channel of the program on the left (top) side of the disc running conventionally in a clockwise format, and the right channel on the right (bottom) side of the disc in a counterclockwise fashion. This was accomplished simply by flipping the stylus around front-to-back in the recording head, and introducing a figure-8 flip in the lathe drive belt, causing the recording to still be made outside-in, but in reverse.

To play the disc, a pedal was depressed to separate the twin gramophone heads which faced one another across the turntable and load the disc vertically as in a jukebox. Then the pedal was very carefully released again in order to set the heads upon the disc for play. As the pedals were spring loaded, most of the records were destroyed by the two heavy gramophone heads crashing into the disc when the load pedal was released.

The format died mainly because of the brittleness of 78s as described above, and also because some discs were produced in an offset format for players with heads at opposite sides of the turntable, while others were produced for playback on machines with gramophone heads on the same side. Playing a disc made for one on a player made for the other would induce a half-revolution difference in the program, similar to trying to play a manual-sequence album on a changer where the sides would be out of sequence. ^{[citation needed]}

Utilizing another technique borrowed from vintage Vitaphone recordings which accompanied sound films in the 1920s before the advent of sound-on-film, arrows were inscribed on the master indicating the start of the lead-in groove. Stampers could then be either aligned with or staggered from one another for production, which, due to the exacting care needed for stamper alignment was accomplished at the long-dormant Vitaphone disc production facilities which produced the originals.

For a good visual of the early problems associated with Vitaphone, see the recording scene and the movie-preview scene of Gene Kelly in MGM's Singin' in the Rain. Unlike most phonograph discs, the needle on Vitaphone records moved from the inside of the disc to the outside, a practice which would be half-borrowed by live recording engineers of those pre-tape days, recording odd sides of a live performance conventionally outside-in, and even sides of a program inside-out back and forth between twin disc recording lathes. When plated and pressed, these discs were produced with a hybrid of manual-operator and automatic-changer sequence called "DJ disc sequence," so that an operator would never have to flip a disc over in order to continue.

This inline/staggered heads idea from twin-sided stereo shellac 78s would later be utilized in competing home-stereo tape recording formats of the early 1950s, once again, one machine being unable to play stereo recordings made on the other. This time, however, one format, Inline, won out.

After lying dormant for over 40 years, the idea of having one head on the front of a disc and one head on the back was picked up in the 1970s by Sharp Electronics and used in a space-saving turntable design to play both sides of a vertically-oriented LP in sequence without having to move the stylus from one side to the other (as in a two-sided LaserDisc player where the pickup travels from bottom to top to play the other side). Each side had its own cartridge and stylus, and the three-inch platter could spin in either direction, allowing for as much as 45 minutes of uninterrupted music.

The Cook twin-groove stereo system borrowed from this but put both grooves on the same side of the disc, engraving the left channel of the groove beginning near the edge of the disc and the right channel beginning near a point halfway through the recording and concluding near the label. A twin-lateral pickup was used for playback.

In the Westrex system, the lateral-vertical system described above is tilted 45 degrees, allowing each channel to drive the cutting head at a 45 degree angle to the vertical, sharing equally in both the lateral and vertical modulations and eliminating the need for a matrix when encoding from a stereo source.

During playback the combined signal is sensed by a left channel coil mounted diagonally opposite the inner side of the groove, and a right channel coil mounted diagonally opposite the outer side of the groove.^[37]

It is helpful to think of the combined stylus motion in terms of the vector sum and difference of the two stereo channels. Effectively, all vertical stylus motion conveys the L-R difference signal, and horizontal stylus motion carries the L+R summed signal.

The advantages of the 45/45 system are:

greater compatibility with monophonic recording and playback systems. A monophonic cartridge will reproduce an equal blend of the left and right channels instead of reproducing only one channel. (However many monophonic styli would damage a stereo groove, leading to the common recommendation to never use a mono cartridge on a stereo record.) Conversely, a stereo cartridge reproduces the lateral grooves of monophonic recording equally through both channels, rather than one channel;
a more balanced sound, because the two channels have equal fidelity (rather than providing one higher-fidelity vertically recorded channel and one lower-fidelity laterally recorded channel); and
higher fidelity in general, because the "difference" signal is usually of low power and thus less affected by the intrinsic distortion of hill-and-dale recording.

This system was invented by Alan Blumlein of EMI in 1931 and patented the same year. EMI cut the first stereo test discs using the system in 1933 see "Bell Labs Stereo Experiments of 1933." It was not used commercially until a quarter of a century later.

Stereo sound provides a more natural listening experience where the spatial location of the source of a sound is, at least in part, reproduced.