Analogue disc record

The analogue disc record was the main technology used for storing recorded sound in the 20th century. Its common names included gramophone record (British English), phonograph record (American English), record, album, disc, black disc, vinyl, and (more informally) platter or sides. The name was often prepended with the extra longplay or long play, which lent it the acronymic name LP.

Table of contents
1 Introduction
2 Early history
3 Post-War formats
4 The analogue record mastering and pressing process
5 The analogue record in the era of digital technology
6 See also

Introduction

It is an audio storage medium, most commonly used for preserving music. A gramophone record almost always consists of a disc engraved with a single concentric spiral groove on one side of the disc, in which a stylus or needle runs, from the outside edge towards the centre. (A small number of early phonograph systems and radio transcription discs started the groove from the inside rather than the edge of the disc, and a small number of novelty records were manufactured with multiple separate grooves.) The record spins at a certain speed, while the needle is held on a mobile arm, which gradually moves toward the centre of the record as it follows the spiral. Since the late 1910s, both sides of the record have usually been used for playing surfaces.

By the early 1990s digital media such as the compact disc surpassed the analogue disc in popularity, but analogue discs continue to be made (although in very limited quantities) into the 21st century.

Early history

Recording on disc as opposed to phonograph cylinder had been contemplated and experimented with by such inventors as Charles Cros, Thomas Edison, Chichester Bell, but the first to actually develop usable disc record technology was Emil Berliner, a German working in Washington, D.C, in 1884. He got patents in Berlin and Washington, DC for the record and the gramophone in 1887.

The first disc recordings for phonographs or gramophones were commercially marketed in 1895, and they gradually overtook the earlier phonograph cylinder as the dominant medium of recorded sound by the 1910s.

Early analogue disc records were originally made of various materials including hard rubber. In the early 20th century earlier materials were largely replaced by a rather brittle formula known as "shellac". The mass production of shellac records began in 1898 in Hanover, Germany. Shellac records were the most common until about 1950. Earliest speeds of rotation varied widely, but by 1910 records rotating at or about 78 or 80 times in one minute became standard, with 78 rpm becoming the standard in the late 1920s. This gave a common name for such records as 78s (or "seventy-eights"). This term did not come into use until after World War II when a need developed to distinguish the 78 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. Standard records was also used, although the same term had also been used earlier for 2 minute cylinders.

In the 1890s early discs were usually 7 inches in diameter. By 1910 the 10-inch record was by far the most popular standard, holding about 3 minutes of music or entertainment on a side. 12-inch records were also commercially sold, mostly of classical music or operatic selections, with 5 minutes of music per side.

Such records were usually sold separately, but sometimes in collections held in paper sleeves in a cardboard or leather book, similar to a photograph album, and called record albums. Also, empty record albums were sold that customers could use to store their disc records in.

Post-War formats

After World War II, the "78" was replaced by two competing formats: the 33 1/3 rpm (often just referred to as to 33 rpm), and the 45 rpm. The 33 1/3 rpm LP (for "Long Play") format was developed by Columbia Records and marketed in 1948. RCA Victor had developed the 45 rpm format years earlier but had not marketed it until 1949, in response to Columbia. Both types of new disc used narrower grooves, intended to be played with a smaller stylus, than the old "78s", so the new records were sometimes called Microgroove. All of these companies agreed to a common recording standard for improving quality called RIAA equalization.

The older 78 format continued to be mass produced along side the newer formats into the 1950s (and in a few countries, such as India, into the 1960s).

About the same time the most common substance for making disc records became vinyl. All speeds of records were made in various sizes, mainly 7, 10 and 12 inches diameter; the 7-inch being most common for the 45rpm, the 10-inch for the 78 (and the first few years of 33&1/3 production), and the 12-inch for the 33 from the mid 1950s on.

  • A 45-rpm 7-inch was called a 45 (forty-five) or a single, because it usually held a single song on each side. It took over this role from the older standard of the 10-inch 78. Early on RCA sold albums of 45s of all types of music including long classical compositions, but after a few years even RCA recognized that the LP format developed by their competitor Columbia was a more practical format for most recordings other than singles. American 45s have 3/4" centre holes. Pressings made in other countries often have 1/4" holes, the same as LPs, set into removable 3/4" centres.

  • A 45-rpm 12-inch format was introduced in Britain in the late 1970s. These so-called 12-inch singles could carry extended versions of songs, or carry the same material as regular singles with wider spacing between grooves, allowing for higher sound quality than regular singles.

  • A 33-rpm 7-inch was known as an "EP" (extended play), with 2 or 3 songs per side. However, 45-rpm 7-inch EPs were also produced, using narrower groove spacing (and therefore lower sound quality) to carry 2 songs per side.

  • A 33-rpm 12-inch (originally 10-inch) was an "LP" or long-playing record, with from 5 to 10 songs on each side. Because the same amount of music as on an entire album of old style 78s could be fitted on a single disc, some people took to calling these new discs albums even when referring to a single disc. Run time per side tended to increase from about 15 minutes to nearly 30 minutes, but most LPs during the 70s had a combined run time of 40 to 45 minutes, hence the popularity of the C90 compact audio cassette which runs for 45 continuous minutes per side.

  • 16-rpm records, usually 12 inches, were also manufactured. These were of lower audio fidelity and mostly used for spoken word recordings. The most common of these were recorded readings of books made for the benefit of the visually impaired.

Disc records were extremely popular in their heyday, despite their well-known weaknesses. Throughout most of their period of popularity audio quality was below the best technically possible, but disc records were cheap to manufacture, and easy for the buyer to store and play back.

The discs were fragile. Shellac 78s were brittle and would shatter if dropped. While vinyl records were less subject to breakage they were more prone to being scratched on their unprotected surface, and were more easily warped out of shape by heat. Scratches could cause audio clicks and pops; the needle could skip to the next groove, bypassing that portion of the audio track; or it could skip backward, repeating the same portion of track over and over. If the hole in a record was not cut precisely in the centre the grooves would speed up and slow down once per revolution as the needle moved further from and then closer to the centre, causing changes in speed and pitch known as "wow".

Audiophiles would take great care of their records, often playing them on expensive equipment to get the best sound and impart the least wear to the disc. However, even with the best of care, keen ears could often detect slight surface noise and audio degradation after two to five playings of a vinyl record. Repeated use degraded the audio quality further.

As a practical matter, records provided adequate sound quality when treated with care and replaced after a reasonable number of playings. They were the music source of choice for radio stations for decades, and the switch to digital music libraries by radio stations has not produced a noticeable improvement in sound quality. The limitations of recording and mastering techniques had a greater impact on sound quality than the limitations of the record itself, at least until the 1980s.

Records were easy and inexpensive to manufacture, so they could be mass-produced. Also, with the advent of long-playing records, the album cover became more than just packaging and protection, and album cover art became an important part of the music marketing and consuming experience.

The analogue record mastering and pressing process

Recording the disc

For the first several decades of disc record manufacturing, sound was recorded directly on to the master disc (also called the matrix, sometimes just the master) at the recording studio. From about 1950 on (earlier for some large record companies, later for some small ones) it became usual to have the performance first recorded on audio tape, which would could then be processed and/or editied, and then dubbed on to the master disc.

A Record cutter would engrave the grooves into the master disc. Early on theses master discs were soft wax, later on a harder lacquer was used.

Mass producing records

The soft master would then usually be electroplated with a metal, commonly a nickel alloy. When this metal was removed from the master, it would be a negative master (in some companies' terminology, this was called the master; note difference from master disc above). In the earliest days the negative master was used as a mold to press records sold to the public, but as demand for mass production of records grew, another step was added to the process.

The negative master mold is used to create metal positive discs, each called a mother. These mothers would then in turn be used to make more negatives, each called a stamper. The stampers would be used as the molds for the discs sold to the public. The advantages of this system over the earlier more direct system included ability to make more records more quickly by having multiple stampers pressing records at the same time, more records could be pressed from each record since much used molds would eventually wear out, and spare mothers as back ups.

The analogue record in the era of digital technology

Starting in the 1980s, vinyl records were gradually replaced in mainstream music consumer markets with the compact disc (CD). Vinyl records continue to be manufactured and sold today, although it is considered to be a niche market comprised of audiophiles, collectors, and disc jockeys (DJs).

Some audiophiles dispute the superiority of CDs. The lack of hiss or background crackling is dependent on the quality of the original recording. There are also inherent limitations of the 44 kHz sampling rate used for CDs, which tends to distort subtle phase differences that affect the psychoacoustic placement of the sound in the stereo image. The quality and clarity of the sound is very much dependent on the quality of the reproduction equipment, for example the DAC (Digital to analog converter).

The background noise one hears on a vinyl record has been compared to the patina of an oil painting -- a part of the work, not an imperfection to be eliminated; moreover, it has been claimed that some pre-CD recordings were made with this patina in mind. To further cloud the issue, some pop music released on CD has had crackles and hiss added artificially, for effect. See Lo-fi.

See also




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