De-mystifying “Mastering”

The word “Mastering” has been one of the most misunderstood and somehow a controvertial term in Audio Production. Truly, it is a process of Post Production, Quality Check and a Transfer Process to the required Delivery Format for Release.

A ‘Mastering Engineer’ is an individual involved in this process, who has the ability of critial listening of the Audio Programme and taking decisions in the processes involved in finalising the content in terms of Dynamic Range, Tonal Balance, Imaging and Loudness Levels. Obviously, requires a good deal of experience in this field of Audio Engineering as Mastering is the Final Process before the content is released in the Market for consumption.


Mastering begins with carefully listening to the content with the help of a full range playback system with very good Signal to Noise Ratio, Dynamic Range and the ability to reproduce an Accurate Tonal Response, which is a much need requirement for this process. Making decisions on processing the audio content is the next step, where processes like compression, equalisation, imaging (width), Loudness control (Genre specific) and Dither are performed. During a Mix session, the Mixing Engineer has control on the individual elements of the audio content viz, tracks, layers, etc., while the Mastering Engineer works on the Mixed Content, which is usually a Stereo or Surround Mixed Programme where even the slightest change performed can make a difference of Night and Day.

For example, a mixed audio track has all the elements mixed down to the required format of Stereo (2 Channels) or Surround (Multichannel), so if one increased the low (bass) frequencies even by 1 dB, it will effect all the elements which fall within that frequency range. Whereas in a Mix process the Engineer can process each and every element individually. So, too much processing is a big no no while performing Mastering, or else there will be a huge change in the Mix Balance of the Programme.


So what do we need?

A good playback system to start with. And what is a good playback system? Well in simple terms, a good playback system is a system which does not lie to you.

Where does ‘Lie to you’ fit in this process?

To make critical decisions which can effect the quality of the produced content, one requires a system which has the ability to provide a nearly flat frequency response converting the entire audible human hearing range of 20Hz to 20KHz.

A “Mastering Grade” loudspeaker system is the first essential requirement to fulfill this process. Good speakers need good rooms. So, an Acoustically Treated Room goes hand in hand for critical listening. However good your playback system may be, a bad room can ruin it badly. A Mastering Room and a Mix Room are bit different. A Mix Room would be suitable for accurate mixing of various elements in the audio programme, so ideally the room should have an RT (Reverberation Time) of approximately 0.5 seconds. Whereas a Mastering Room is similar to a very quiet Living Room, with the necessary Acoustic Treatment to control Room Reflections, Bass Control etc.

A good Amplifier is a much need requirement to drive ‘Mastering Grade’ loudspeakers. So, power delivery, frequency response and long term reliability are important factors of a good amplifier. Well, now a days, several manufacturers are providing speakers which have very decent onboard amplifier modules as a part of the unit. There are advantages and disadvantages for both types of speakers, better knows as ‘Active’ and ‘Passive’.

As a Mastering Engineer myself, I prefer to use Passive Speakers, but this is not a Rule of any kind. This is a personal choice. In my case I have the flexibility to choose and match the amplifier with my Speakers and Speaker cable as well. All these little factors have played an important role in matching my speakers and amplifier with my Room. But, this may not be the case for you.


Since the introduction of Digital Audio and Formats, the need for good conversion has become a necessity for quality production. Therefore choosing the right type of DAC (Digital to Analogue) becomes important for a Mastering Engineer. There are tons of good converters available in the Market. As per one’s requirement there are various interfaces viz, FireWire, USB 2.0, 3.0, 3.1, Thunderbolt 2, 3, whichever works for you. Ideally a DAC required for a Mastering Room should have a SNR of 115 dB RMS (unweighted) with an extremely stable clock.

Given below are the Specifications of a Typical Mastering Grade DAC:

  • Output level switchable +19 dBu, +13 dBu, +7 dBu, +1 dBu @ 0 dBFS
  • Signal to Noise ratio (SNR) @ +7/+13/+19 dBu: 117 dB RMS unweighted, 120 dBA
  • Signal to Noise ratio (SNR) @ +1 dBu: 115,4 dB RMS unweighted, 118,9 dBA
  • Frequency response @ 44.1 kHz, -0.1 dB: 0 Hz – 20.2 kHz
  • Frequency response @ 96 kHz, -0.5 dB: 0 Hz – 44.9 kHz
  • Frequency response @ 192 kHz, -1 dB: 0 Hz – 88 kHz
  • Frequency response @ 384 kHz, -1 dB: 0 Hz – 115 kHz
  • Frequency response @ 768 kHz, -3 dB: 0 Hz – 109 kHz
  • THD @ -1 dBFS: -112 dB, 0.00025 %
  • THD+N @ -1 dBFS: -110 dB, 0.00032 %
  • THD @ -3 dBFS: -116 dB, 0.00016 %
  • Channel separation: > 120 dB

– Courtesy: RME Audio


Over the years, the Mastering process has moved on from Analogue Tape Machines to a Digital Workstation running on a  PC or Mac Computer. Though many Mastering Engineers still prefer passing the Audio Signal through an Analogue Tape Machine (I am one of them) for a ‘warmer’ audio signal. This is again a personal choice. Signal Processing in the Mastering process is also going through this Hardware vs Plugins war…well both have their advantages and disadvantages. I like using both, again that is not a rule, but a matter of choice. Both the worlds of Hardware and Plugins have excellent solutions for Mastering and choose whatever works for you. Digital Technology has come of age over the last decade. The quality of Plugins, converters, etc have seen a huge improvement over time and are able to deliver very good results.

There are various forms of Mastering. When I began my career, about 22 years ago, I had my initial training on Analoge Tape Machines like the Studer A827 2” 24 Track unit, and we were Mastering down to a Studer A807 and Mitsubishi X86. Mastering was mainly to make sure that all the tracks in the album play at the same level, have a similar tonal balance, basically feel like that they belong to the same family. Ever since the begining of the Loudness War around early 2000’s started this movement of Mastering Engineers pushing the Audio Levels to the available ceiling, really crushing it…killing the Dynamics…well, this was the period of Louder the Better.

Thankfully, things have changed in recent times, where Mastering Engineers are taking good control of Loudness Levels. In this age of Online Music Platforms like Apple Music, Spotify, Amazon, etc, they have specified certain loudness requirements in LUFS (Loudness Units Full Scale), which has brought in some amount of consistency in Loudness Standards. Bodies like EBU (European Broadcasting Union) and ITU (International Telecommunication Union) have specified Loudness Standards for Music, Films, Gaming and Broadcast to mantain consistency, especially for Online Releases.

From Mastering for Tape, Vinyl, CD, Radio, TV, we have come to a point where Mastering goes deeper in to making your production stand out in the market, while maintaining the sensibility of Loudness Standards for today. Mastering does involve the basic processes of quality control, like making sure that there is no audible noise (unless intended by the producer), Adjusting the Fades, Tonal Balance, Adjustment of Dynamics, Imaging and Loudness.

At the end of it all, Mastering is an Art which involves Science and your ability to ‘Master’ the Mix, so it would stand out with an ‘attractive sound’ boosting popularity and ofcourse sales.

I am a Mastering Engineer with 22 years of Work Experience with the Music Industry, and for me each day is a learning process, as each project teaches you something new, something more that what you already knew. I know how to mix, but I don’t unless absolutely necessary. Mastering and Mixing are two different processes, and should be performed by two separate individuals in their respective spaces.

Thank you.

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1 Response

  1. Sushil Anand says:

    Very informative and well written.

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