Master of Recording
A recording master is an original sound recording from which edited copies are made. When recording is done on a magnetic tape, the original tape is known as a master tape.
A master recorded with a multitrack and from which the production process is performed (or recorded live and then mixed) is known as a "multitrack masters". When the tape or disc contains a mix (in mono, stereo or surround) it is called a "mixing master."
Compact discs allow you to record the master data in audio or data format. They also allow you to remix the content. Master's on CD are usually called "gold master". The origin of this term is not clear.
It is common practice to make a copy of the master record, which is known as backup, in case the master disappears or is damaged.
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