Mastering (audio)

Mastering is a form of audio post-production which is the process of preparing and transferring recorded audio from a source containing the final mix to a data storage device called a master recording, the source from which all copies will be produced (via methods such as pressing, duplication or replication). In recent years, digital masters have become common, although analog masters—such as audio tapes—are still being used by the manufacturing industry, particularly by a few engineers who specialize in analog mastering.

Mastering requires critical listening; however, software tools exist to facilitate the process. Results depend upon the intent of the engineer, their skills, the accuracy of the speaker monitors, and the listening environment. Mastering engineers often apply equalization and dynamic range compression in order to optimize sound translation on all playback systems. It is standard practice to make a copy of a master recording—known as a safety copy—in case the master is lost, damaged or stolen.

History

Pre-1940s

In the earliest days of the recording industry, all phases of the recording and mastering were entirely mechanical processes. Performers sang or played into a large acoustic horn and the master recording was created by the transfer of acoustic energy from the diaphragm of the recording horn to the mastering lathe, typically located in an adjoining room. The cutting head, driven by the energy from the horn, inscribed a modulated groove into the surface of a rotating cylinder or disc. These masters were usually made from either a soft metal alloy or from wax; this gave rise to the colloquial term waxing, referring to the cutting of a record.