upPresto 8N Disc Cutting Lathe (1950) used by the Canadian Broadcasting Corporation to record radio programs A disc cutting lathe is a device used to transfer an audio signal to the modulated spiral groove of a blank master disc for the production of

phonograph records A phonograph record (also known as a gramophone record, especially in British English) or a vinyl record (for later varieties only) is an analog sound storage medium in the form of a flat disc with an inscribed, modulated spiral groove. The g ...

. Disc cutting lathes were also used to produce broadcast transcription discs and for direct-to-disc recording.

Overview

Disc cutting lathes utilize an

audio signal An audio signal is a representation of sound, typically using either a changing level of electrical voltage for analog signals or a series of binary numbers for Digital signal (signal processing), digital signals. Audio signals have frequencies i ...

, sent through a cutting

amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It is a two-port electronic circuit that uses electric power from a power su ...

to the cutter head, which controls the cutting

stylus A stylus is a writing utensil or tool for scribing or marking into softer materials. Different styluses were used to write in cuneiform by pressing into wet clay, and to scribe or carve into a wax tablet. Very hard styluses are also used to En ...

. The cutting stylus engraves a modulated spiral groove corresponding to the audio signal into the

lacquer Lacquer is a type of hard and usually shiny coating or finish applied to materials such as wood or metal. It is most often made from resin extracted from trees and waxes and has been in use since antiquity. Asian lacquerware, which may be c ...

coating of the master disc. The

direct metal mastering Direct metal mastering (DMM) is an analog audio disc mastering technique jointly developed by two German companies, Telefunken-Decca ( Teldec) and Georg Neumann GmbH, toward the end of the 20th century after having seen the same technology us ...

(DMM) process uses a copper-coated rather than lacquer-coated disc. Before lacquer discs, master recordings were cut into blank wax discs. Once complete, this master disc is used to produce matrices from which the record is pressed. For all intents and purposes, the finished record is a facsimile of this master disc.

History

Prior to the success of Western Electric's "Westrex" system, master discs were produced acoustically and without electricity. In 1921, John J. Scully, a former Columbia Phonograph Company employee, designed and built a weight-driven lathe specifically designed for use by phonograph manufacturers. The first Scully lathe was sold to Cameo Records. John's son, Lawrence, founded Scully Recording Instruments. In 1924,

Western Electric Western Electric Co., Inc. was an American electrical engineering and manufacturing company that operated from 1869 to 1996. A subsidiary of the AT&T Corporation for most of its lifespan, Western Electric was the primary manufacturer, supplier, ...

purchased a Scully weight-driven lathe to demonstrate their "Westrex" cutter head and electronics for both the Columbia Phonograph Company and

Victor Talking Machine Company The Victor Talking Machine Company was an American recording company and phonograph manufacturer, incorporated in 1901. Victor was an independent enterprise until 1929 when it was purchased by the Radio Corporation of America (RCA) and became ...

. Both companies began using the Westrex system for recording sessions in 1925 after agreeing to license the system from Western Electric. In 1931, German manufacturer Georg Neumann & Co. introduced the AM31 disc-cutting lathe, which employed a direct-drive design. Two years later, Neumann introduced a portable lathe capable of making recordings on location. Imports of Neumann lathes into the United States were restricted, however, and Neumann lathes were not imported to the United States until the 1960s. Scully dominated the U.S. marketplace for professional recording lathes from the 1930s to the 1960s, and almost all American lacquer masters were cut using a Scully lathe, often fitted with the Westrex cutter head and electronics. In 1947, the Presto 1D, Fairchild 542, and Cook feedback cutters represented major improvements in disc-cutting technology. In 1950 Scully Recording Instruments introduced a disc cutting lathe with variable pitch, which made it possible to vary the width of the grooves (i.e. the pitch) of a master disc, simultaneously conserving the available recording space of the disc while preserving the dynamics and fidelity of the recorded material. Five years later, the company introduced automation for this variable pitch feature. In 1957, Westrex demonstrated the first commercial "45/45" stereo cutter head. In 1966, Neumann introduced the VMS66, followed by the VMS70 (1970) and the VMS80 (1980), which introduced variable pitch to Neumann's offerings, reducing speed fluctuations to achieve smoother sound and extended dynamic range. Unlike other systems, Neumann's disc cutting system was complete and included the lathe, cutter head, and electronics.

References

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External links

Audio Record Magazine: Quick Facts On Disc Recorders (October 1952)
Sound recording technology