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Mastering, a form of audio post-production, is the process of preparing and transferring recorded audio from a source containing the final mix to a data storage device (the master); the source from which all copies will be produced (via methods such as pressing, duplication or replication). See also Filmmaking Post-production occurs in the making of motion pictures, television programs, Videos audio recordings A data storage device is a device for recording (storing information (data See also CD manufacturing, Date=July 2007 In optical disc manufacturing replication is the process of producing discs via methods that do not involve burning blank The format of choice these days is digital masters, although analog masters, such as audio tapes, are still being used by the manufacturing industry and a few engineers who specialize in analog mastering.

Bob Katz, a published author and mastering engineer, has said that mastering is an art form and it should be relegated to a mastering engineer. A mastering engineer is one skilled in the practice of taking Audio (typically musical content that has been previously mixed in either the analog or Digital This task should not be executed even by the best and most experienced multi-track audio and live music engineers. [1]

View of a mastering studio
View of a mastering studio

Contents

History

Pre-1940s

In the earliest days of the recording industry, all phases of the recording and mastering process were entirely achieved by mechanical processes. Performers sang and/or played into a large acoustic horn and the master recording was created by the direct transfer of acoustic energy from the diaphragm of the recording horn to the mastering lathe, which was typically located in an adjoining room. In a Loudspeaker, a diaphragm (also known as the cone) is the thin semi-rigid membrane attached to the central Magnet. A lathe (ˈleɪð is a Machine tool which spins a block of material to perform various operations such as Cutting, Sanding, Knurling The cutting head, driven by the energy transferred 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. A master recording is an original Recording, from which copies may be made Wax has traditionally referred to a substance that is secreted by Bees ( Beeswax) and used by them in constructing their

After the introduction of the microphone and electronic amplification in the late 1920s, the mastering process became electro-mechanical, and electrically driven mastering lathes came into use for cutting master discs (the cylinder format by then having been superseded). A lathe (ˈleɪð is a Machine tool which spins a block of material to perform various operations such as Cutting, Sanding, Knurling

However, until the introduction of tape recording, master recordings were almost always cut direct-to-disc. Direct to disk recording refers to methods by which digital audio and video are recorded to portable storage media such as Hard drives and DVDs Direct to disk can Artists performed live in a specially designed studio and as the performance was underway, the signal was routed from the microphones via a mixing desk in the studio control room to the mastering lathe, where the disc was cut in real time.

Only a small minority of recordings were mastered using previously recorded material sourced from other discs.

Advances

The recording industry was revolutionized by the introduction of magnetic tape in the late 1940s, which enabled master discs to be cut separately in time and space from the actual recording process. Magnetic tape is a medium for Magnetic recording generally consisting of a thin magnetizable coating on a long and narrow strip of Plastic. Although tape and other technical advances dramatically improved audio quality of commercial recordings in the post-war years, the basic constraints of the electro-mechanical mastering process remained, and the inherent physical limitations of the main commercial recording media—the 78 rpm disc and the later 7-inch 45 rpm single and the 33-1/3 rpm LP record—meant that the audio quality, dynamic range, and running time of master discs were still relatively limited compared to later media such as the compact disc. A gramophone Dynamic range is a term used frequently in numerous fields to describe the Ratio between the smallest and largest possible values of a changeable quantity such as in Sound A Compact Disc (also known as a CD) is an Optical disc used to store digital data, originally developed for storing digital audio

Running times were constrained by the diameter of the disc and the density with which grooves could be inscribed on the surface without cutting into each other. Dynamic range was also limited by the fact that, if the signal level coming from the master tape was too high, the highly sensitive cutting head might jump off the surface of the disc during the cutting process.

From the 1950s until the advent of digital recording in the late 1970s, the mastering process typically went through several stages. Once the studio recording on multi-track tape was complete, a final mix was prepared and dubbed down to the master tape, usually either a single-track mono or two-track stereo tape. Audio mixing is the process by which a multitude of sound sources are combined into one or more channels A master recording is an original Recording, from which copies may be made Monaural (often shortened to mono) sound reproduction is single-channel Stereophonic sound, commonly called stereo, is the reproduction of Sound, using two or more independent audio channels through a Symmetrical

Prior to the cutting of the master disc, the master tape was often subjected to further electronic treatment by a specialist mastering engineer. A mastering engineer is one skilled in the practice of taking Audio (typically musical content that has been previously mixed in either the analog or Digital After the advent of tape it was found that, especially for pop recordings, master recordings could be optimized by making fine adjustments to the balance and equalization prior to the cutting of the master disc.

Mastering became a highly skilled craft and it was widely recognized that good mastering could make or break a commercial pop recording. As a result, during the peak years of the pop music boom from the 1950s to the 1980s, the best mastering engineers were in high demand. Pop music as a genre features a noticeable rhythmic element catchy melodies and hooks, a mainstream style and conventional structure

In large recording companies such as EMI, the mastering process was usually controlled by specialist staff technicians who were conservative in their work practices. These big companies were often reluctant to make changes to their recording and production processes—for example, EMI was very slow in taking up innovations in multi-track recording and they did not install 8-track recorders in their Abbey Road Studios until the late 1960s, more than a decade after the first commercial 8-track recorders were installed by American independent studios. Multitrack recording ('multitracking' or just 'tracking' for short is a method of Sound recording that allows for the separate recording of multiple sound sources to create Abbey Road Studios, established in November 1931 by EMI in London, England, is a Recording studio located at number 3 Abbey Road, As a result, by the time The Beatles were making their groundbreaking recordings in the mid-1960s, they often found themselves at odds with EMI's mastering engineers, who were unwilling to meet the group's demands to push the mastering process because it was feared that if levels were set too high it would cause the needle to jump out of the groove when the record was played by listeners. The Beatles were a pop and rock band from Liverpool, England formed in 1960 A mastering engineer is one skilled in the practice of taking Audio (typically musical content that has been previously mixed in either the analog or Digital

Digital technology

Optimum Digital Levels with respect to the Full Digital Scale (dBFSD)
Optimum Digital Levels with respect to the Full Digital Scale (dBFSD)

In the 1990s, electro-mechanical processes were largely superseded by digital technology, with digital recordings transferred to digital masters by an optical etching process that employs laser technology. A laser is a device that emits Light ( Electromagnetic radiation) through a process called Stimulated emission. The digital audio workstation (DAW) became common in many mastering facilities, allowing the off-line manipulation of recorded audio via a graphical user interface (GUI). A digital audio workstation (DAW is an electronic system designed to record, edit and play back digital audio Although many digital processing tools are common during mastering, it is also very common to use analog media and processing equipment for the mastering stage. [2]

Just as in other areas of audio, the benefits and drawbacks of digital technology compared to analog technology is still a matter of debate. However, in the field of audio mastering, the debate is usually over the use of digital versus analog signal processing rather than the use of digital technology for storage of audio. [2]

Although in reality there isn't such a thing as an "optimum mix level for mastering", the example on this picture to the right only suggests what mix levels are ideal for the studio engineer to render and for the mastering engineer to process. [3] It's very important to allow enough headroom for the mastering engineer's work. Many mastering engineers working with digital equipment would agree that a minimum of 3 to 6 dB of available headroom is critical to perform good mastering. Ideal peak levels should not exceed -3dBFSD and the average sum of the left and right channels should be at around -10 to -18 dBFSD (As shown on the picture to the right).

There are mastering engineers who feel that digital technology, as of 2007, has not progressed enough in quality to supersede analog technology entirely. Many top mastering studios, including Bernie Grundman Mastering (which has mastered 37 Grammy-nominated albums), and Gateway Mastering, still embrace analog signal processing (such as analog equalization) within the mastering process. Bernie Grundman is an American audio engineer. Biography He is most known for his mastering work and his studio Bernie Grundman Mastering Bob Ludwig (b Circa 1945 is an American mastering engineer He is a well known and respected figure within the music industry Analog signal processing is any Signal processing conducted on Analog signals by analog means Additionally, the latest advances in analog mastering technology include 120V signal rails for previously unavailable headroom of 150dB as well as frequency response ranging from 3Hz to 300kHz. In order to duplicate this frequency response in digital domain, a sampling rate of at least 600kHz would be required, by the Nyquist–Shannon sampling theorem. The Nyquist–Shannon sampling theorem is a fundamental result in the field of Information theory, in particular Telecommunications and Signal processing However, it is pertinent that the extremes in this frequency range (3 Hz - 300kHz), are effectively inaudible, existing outside the range of most professional microphones.

Process

The source material is processed using equalization, compression, limiting, noise reduction and other processes. Equalization (or equalisation, EQ) is the process of changing the frequency envelope of a sound in Audio processing. Dynamic range compression, also called DRC (often seen in DVD player settings or simply compression, is a process that reduces the Dynamic range of Noise reduction is the process of removing Noise from a signal. Subsequently, it is rendered to a medium such as CD or DVD. This mastered source material is also put in the proper order at this stage. This is commonly called the assembly or track sequencing. More tasks such as editing, pre-gapping, leveling, fading in and out, noise reduction and other signal restoration and enhancement processes can be applied as part of the mastering stage.

The specific medium varies, depending on the intended release format of the final product. For digital audio releases, there is more than one possible master medium, chosen based on replication factory requirements or record label security concerns. Digital audio uses Digital signals for Sound reproduction. This includes analog-to-digital conversion, digital-to-analog conversion, storage

A mastering engineer may be required to take other steps, such as the creation of a PMCD (Pre-Mastered Compact Disc), where this cohesive material needs to be transferred to a master disc for mass replication. PMCD (PreMaster CD is a specially formatted recordable Compact Disc designed to be sent to a CD pressing plant for replication A good architecture of the PMCD is crucial for a successful transfer to a glass master that will generate stampers for reproduction.

The process of audio mastering varies depending on the specific needs of the audio to be processed. Steps of the process typically include but are not limited to the following:

  1. Transferring the recorded audio tracks into the Digital Audio Workstation (DAW) (optional).
  2. Sequence the separate songs or tracks (The spaces in between) as it will appear on the final product (for example, an Audio CD).
  3. Process or "sweeten" audio to maximize the sound quality for its particular medium.
  4. Transfer the audio to the final master format (i. e. , Red Book-compatible audio CD or a CD-ROM data, half-inch reel tape, PCM 1630 U-matic tape, etc. ).

Examples of possible actions taken during mastering:

  1. Edit minor flaws.
  2. Apply noise reduction to eliminate hum and hiss.
  3. Adjust stereo width.
  4. Add ambience.
  5. Equalize audio between tracks.
  6. Adjust volumes.
  7. Dynamic expansion.
  8. Dynamic compression.
  9. Peak limit the tracks. In Electronics, a limiter is a circuit that allows signals below a specified input power to pass unaffected while attenuating the peaks of stronger signals that exceed this input

The guidelines above are mainly descriptive of the mastering process and not considered specific instructions that may or may not be applied in a given situation. Mastering engineers need to examine the types of input media, the expectations of the source producer or recipient, the limitations of the end medium and process the subject accordingly. General rules of thumb can rarely be applied.

Audio mastering tools

See also

References

  1. ^ Bob Katz The Craft of Mastering
  2. ^ a b Mix Magazine: Issues in Modern Mastering
  3. ^ Bob Katz Mixing Tips

Recommended reading

External links

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