Half-speed mastering is a technique occasionally used when cutting the acetate lacquers from which

phonograph records A phonograph record (also known as a gramophone record, especially in British English), or simply a record, is an analog sound storage medium in the form of a flat disc with an inscribed, modulated spiral groove. The groove usually starts near ...

are produced. The cutting machine platter is run at half of the usual speed (16

rpm Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimension ...

for 33 rpm records) while the signal to be recorded is fed to the cutting head at half of its regular playback speed. The reasons for using this technique vary but it is generally used for improving the high-frequency response of the finished record. By halving the speed during cutting, very high frequencies that are difficult to cut become much easier to cut since they are now mid-range frequencies.

Mobile Fidelity Sound Lab Mobile Fidelity Sound Lab (MFSL or MoFi) is a record label specializing in the production of audiophile issues. The company produces reissued vinyl LP records, compact discs, and Super Audio CDs and other formats. History Recording enginee ...

used half-speed mastering for its Original Master Recording LP's.

References

Audio storage {{Sound-tech-stub