Technical data and formats of the record

The vinyl record uses a mechanical process for storing sound information in which the sound is recorded in a spiral groove. Various mechanical or electrical pickup systems can be used for playback. The technical properties of the record are defined in standards such as DIN IEC 98.

The various record formats have changed considerably over time in order to optimize playing time, frequency response and durability. From the beginning, they were defined in centimeters; the English inch designations are only approximations. Some standard formats have proven to be particularly common:

The single has a diameter of 17.5 cm and a center hole size of 1 1⁄2″ or 38.1 mm. It is normally played at 45 revolutions per minute and offers a playing time of approx. 4-5 minutes per side.

The 10″ single has a diameter of 25.0 cm and is also usually played at 45 revolutions per minute. In the 1950s to 1970s, a playback speed of 33 1⁄3 or 78 revolutions per minute was also common. However, this form of single is rarely used today for new releases.

The Maxi-Single (Twelve-Inch) with a diameter of 30.0 cm is mainly played at 45 revolutions per minute, but can also be used at 33 1⁄3 revolutions per minute. The playing time is approx. 16 minutes per side.

The extended play (EP) is an intermediate format between the single and the long-playing record. It can have a diameter of 17.5 cm or 30.0 cm and is played at different playback speeds of 45 or 33 1⁄3 revolutions per minute. The playing time is between 5 and 8 minutes per side.

The long-playing record (LP) has a diameter of 30.0 cm and is usually played at 33 1⁄3 revolutions per minute. Its playing time is around 20 to 25 minutes per side. For a short time, there were also long-playing records with 16 2⁄3 revolutions per minute, which reached a playing time of up to 60 minutes per side, but were only suitable for voice recordings due to their limited sound quality.

There are also intermediate formats with diameters of 2″, 4″, 5″, 6″, 8″, 9″ and 11″, but these are very rare. The specified play times are only guide values and can vary depending on various factors, such as the bit deflection and the low-frequency components.

Plate fonts

There are three main engraving processes, two of which are still used today. The groove width has been continuously reduced over the years. Whereas shellac records had a groove width of 120 µm (normal groove), the microgroove generally used today is 40 µm wide without modulation; the groove base has a radius of 8 µm. The groove spacing here is approx. 70 µm with linear feed without the use of filler fonts.

The one from Thomas Alva Edison and Pathé is based on the fact that the information is imprinted on the record by the depth of penetration of the engraving pen. The depth is directly proportional to the amplitude of the recorded signal. Although this method enables the reproduction of high frequencies, it requires a higher contact force of the pickup, which can lead to greater wear of the record.

The lateral typeface introduced by Emil Berliner is characterized by a horizontal deflection of the groove. It offers a greater dynamic range than gravure type and facilitates the production of copies. In addition, crackling is significantly reduced compared to gravure type.

The flank writing developed by Alan Blumlein and marketed by EMI made mono-compatible stereo recordings possible for the first time. The sound information for the left and right channels is imprinted in the 45° flanks of the groove, which ensures downward compatibility with mono systems.

The Rhenish fill font method invented by Eduard Rhein controls the groove spacing on the sound carrier. sound carrier depending on the volume of the audio material. This allows the playing time to be extended, whereby the additional playing time varies depending on the program.

Scanning of records

Depending on the groove size, the scanning of records requires different styli with different radii of curvature. Typical radii for spherical styli are as follows:

• Normal groove: 65 µm
• Microgroove: 25 µm
• Stereorille: 15 µm

While the normal groove is used for shellac records (78 revolutions per minute), the microgroove is used for mono records of the 1950s and 1960s and the stereo groove for today’s stereo records. Modern stereo grooves, however, often use improved stylus grindings with smaller and more differentiated rounding radii.

The playing time of an LP side at 33 1⁄3 revolutions per minute is limited by technical factors and the desired sound quality. As a rule, playing times of up to 25 minutes per side are possible without any loss of quality. In the pop and rock sector, however, longer playing times of up to approx. 28 minutes, and in some cases even over 30 minutes, are possible. However, higher levels and a high bass content can have a negative effect on the playing time, as they require greater excursions. To maximize the sound quality, you should avoid cutting too deeply into the record.

The lifespan of a vinyl record can be extended care and storage practically unlimited. However, mechanical wear can occur during playback with a needle, which shortens the service life and impairs the sound quality. This wear can be avoided by optical scanning, e.g. with a laser turntable.