Understanding Mastering

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Written by Edward Vinatea.

Lou Waxman Columbia Studio A with 3 54s
Early days of mastering: Lou Waxman at the Columbia Studio A with 3 54’s (Photo courtesy of George Schowerer) .

Table Of Contents

    1. Preamble
    2. What Is mastering?
    3. What is a mastering engineer required to have in order to provide this service?
    4. Realistic Mastering Results
    5. Grading Mix Quality Results
    6. The Three Main Conditions For DIY Mastering
      1- A Digital Audio Workstation
      2- Fairly ‘accurate’ speaker monitors
      3- Acoustically conditioned room
    7. Conclusion
    8. (New) Watch Understanding Mastering on Youtube

The first mastering engineers were people in charge of cutting a flat transfer of the sound recording from reel tape to a disc and thus, it was the advent of tape recording technology what allowed for the first time these audio technicians or “mastering engineers” to modify, edit and sequence the content of any recording prior to cutting to disc.


This disc would then be used as the “master” for mass replication hence the word “mastering”. In those days it was a mundane function that any beginning audio engineer technician could perform inside a four wall room.


The main part of this function, but not the only one, was to check upon the sound quality during transfers.


As years went by and progress in audio technology was made, mastering engineers started to use two key sound reinforcement pieces of gear: the audio compressor and the equalizer.


The recordings could now be tonally changed and re-balanced to optimize the transfers to discs. By the 1950’s, this skill of optimizing the disc’s physical constraints gave mastering engineers a new-found importance and they were – from then on – considered to be in a league of their own.


Technology has advanced to a point that is conceivable to create records very inexpensively. Most musicians today (especially those in the indie circuit) are recording and mixing their own music like never before. But unfortunately, technology alone doesn’t necessarily guarantee the making of great records.


Many speaker targets to hit.

The process of mastering to achieve good speaker translation for all existing playback systems {see illustration} can be a daunting task and a real challenge to any so called ‘mastering engineer’ (“M.E.”).


But,  seasoned M.E.’s listening inside acoustically fine tuned mastering rooms will adjust recordings day in and day out, and compile them with similar frequency balance and perceived loudness to a final storage medium {e.g. wav computer file, CD, tape reel, etc} for proper playback system translation.


As one can see in the illustration, there are many targets to hit and the resulting master source would have to translate and sound ‘on point’ on those speaker systems to be considered a well done mastering job. However, these sonic results are always best when processing from great sounding mixes, that is, great mixing is the key to a great master!


Having said all that and since the subject at hand is mastering, we will not discuss recording or mixing techniques and will concentrate all our attention to the subject of mastering alone.


But it has to be said that – in my humble opinion, of course – “mastering” is often a very misunderstood and utterly underestimated process, while pretty often, mastering engineers are highly overrated in the process. To understand all of this one needs to put things in a realistic perspective first.



What Is Mastering?

Short Answer:

Mastering is the last step in the recording process executed by an experienced and specialized sound technician who checks the quality of the audio or music for best system translation, preparing the audio content for both; mass replication and broadcasting.


This preparation may consists of track sequencing {the order of the tracks}, track pq coding or pre-gapping {the spaces between these tracks} and/or other types of code programming {e.g. ISRC, UPC bar and text for CD}. Some mild signal processing maybe required in order to create a cohesive audio material but sometimes this becomes the main expectation or focal point of the engineer.


Long Answer:

From a historical point of view the name to this process was originally ‘pre-mastering’ while “mastering” used to be referred to the actual creation at the manufacturing plant of the replication medium {the master itself}.


Old Abbey Road mastering
Back in the early days, a view of Abbey Road mastering room.

But these days pre-mastering is synonymous of mastering which from a technical point of view is also the process of optimizing all individual frequency levels to meet ‘industry standards’.


The mastering process is – for the most part – source dependent, so the better your mix, the better the results to be obtained. Because of this, results vary from recording to recording making mastering a crucial step prior to manufacturing and broadcasting for best system translation.

One way to look at this process is the way one looks at publishing on the web; while it has given everybody the freedom to create web pages on just about any subject, there is usually no proper editorial content. So, a mastering engineer acts sort of like an ‘editor’ making sure that anything written is spelled out right and displayed or presented to a worldwide audience correctly.


A mastering engineer {“M.E.”} should be able to make a great mix sound louder, punchier and clearer better than any other type of audio engineer without making – in the process – a significant sonic sacrifice.


Next to experience a mastering engineer has all the tools needed (e.g. the gear and the acoustic environment), but one is certainly not the deciding factor to achieve great recordings. However, since most music production mixes don’t come out – in terms of tonal balance – perfect all of the time, mastering is also a necessary step to improve upon system translation by means of harmonic balancing.


Many engineers regard their mastering process as a way of adding impact, color and vibe to the audio material they work on in a proprietary manner, which is fine as long as they don’t introduce too much circuit noise and harmonic distortion into their signal chain.


The job may also include disc assembly and quality control for manufacturing purposes when and if required by their clients.

What is a mastering engineer required to have in order to provide this service?

Acoustic Room For Mastering
An acoustically designed mastering room environment.

Mastering should preferably be conducted inside an acoustically fine tuned, neutral response room, or one that can control sound reflections and it’s equipped with a flat response speaker monitoring system. In addition, if an inexperienced engineer is performing this task without the foregoing and the guidance of spectrum analysis, chances are that a harmonically imbalanced master recording will be sent to the manufacturing plant for mass replication and that could have in the long run serious consequences.



Realistic Mastering Results:

  1. Bad mixes always yield bad mastering results, no exceptions.
  2. Mediocre mixes yield inconsistent mastering results. However, some significant improvements are usually achieved when done right and some results may even meet industry standards.
  3. Good mixes are always elevated to industry standards and sometimes the results are even dramatic.
  4. Great mixes meet by default ‘industry standards’, but with the exception that there is usually little room for improving upon system translation, and the ideal RMS level which has to be finalized. In most cases, other than increasing loudness, the results may only be perceived as subtle.


Grading Mix Quality Results

You may ask the “M.E.” to critique or grade your mix, but this isn’t really something that should be expected free of charge. Many engineers consider this nothing but a consultation, and because it does engage their full attention and this takes time, it requires paying a fee. Your miles may vary, but grading a mix from the usual ‘A’ as the best mix and’ E’ the worst, you can expect a good mastering engineer to raise the quality level to about half grade, e.g, from a C (mediocre) quality to a C+.


Or, we can also grade with a 5 star rating system:

from an ‘A’ grade mix (5 stars) to the lowest, ‘E’ grade mix (1 star).

That being said, 5 star mixes are extremely rare and require an audio engineer with many years of experience in mixing {10 yrs+ being the usual}. This also means that the mastering engineer other than to boost and match levels, very little (or nothing) will do to the mix.


Does that sound to you like cheating? It’s not, mastering is not always about what you do to a mix, but what you don’t .


Because, even for one to arrive to the conclusion that the mix is perfect and that it will translate fine on all playback systems, requires many years of mastering experience, very good monitoring environment, or both.


In addition, a highly experienced and skilled mastering engineer using quality tools to process audio could possibly raise the quality by one whole grade, e.g., from ‘B’ (good) quality to ‘A’ (excellent).


This is why it’s so important to choose a reputable mastering engineer. If you don’t, this mix that you have spent lots of money on and a long time to get it sounding just right, is actually going to be degraded in sound quality at this particular last step because of the incompetency or inexperience of a mastering engineer.


Disc stamper: the manufacturing of optical discs can be viewed as two separate operations. The first operation is stamper making, which includes mastering and electroforming (galvanics). The second operation is replication, which includes utilizing the stamper for injection molding, finishing, and printing the replication.

Make sure you are – at the very least – working with a mastering engineer registered on The Directory Of Mastering Studios to minimize the risk of being provided with bad results or worse, getting ripped off.


That being said, bad mixes can potentially sound a bit better by a skilled engineer although never as good as well mixed records. There is certainly no chance at all that it will sound like a mix produced at a state-of-the-art facility.


If you are not sure you have a good mix, seek professional advice. A reputable mastering engineer could tell you what you really have if you ask politely and are patient enough with his busy schedule. Some give you this advice as part of their mastering fees, others as I said, charge as a separate service upfront.


A mastering engineer who wants you as a client might tell you exactly what is wrong and what needs adjustment even for free, but don’t expect one to volunteer an opinion. You need to ask first. One may also not even charge you for this expert opinion because after you make new revisions, you’ll probably be more inclined to hire one for one’s patience, great suggestions and professional advice.


Again, don’t expect this to be part of the service; the most successful mastering engineers have very good reasons not to form opinions on anybody’s mixing work and they just process whatever is given, no questions asked. Some fear that they may offend the sensibilities of the mixing engineer, especially if the client was behind the mixing. Therefore, due to the nature of the business this could present to some M.E.’s a big conflict of interest, one that they wouldn’t want to touch with a 10 foot pole.


I certainly will not discuss a mix that came from a record company (especially major), but I might do it if I am asked by a newbie mixing engineer. Now, if you want to attempt doing this mastering work all by yourself, please read on.

The Three Main Conditions For DIY Mastering
In order to attempt mastering your own mixes, you need to have at the very minimum the following:

  • 1. A Digital Audio Workstation {DAW} with a mastering software installed.
  • 2. A pair of fairly ‘accurate’ speaker monitors (as close to flat response as possible).
  • 3. An acoustically ‘conditioned’ room (as accurate as one can get it to be).

If you don’t have conditions 2 and 3, do it at your own risk.


1- A Digital Audio Workstation

I don’t want to get focused on this requirement too much. Many of you know about workstations and computers more than I, and thus, I’ll keep it simple. The DAW is basically a computer system with an audio card to capture and to output sound. Better results can be achieved by adding high quality AD/DA signal converters, though this benefit comes with a higher price tag.

There are some converters that are a lot more expensive than both the computer and mastering software put together. But still, there are units that accomplish the job under $1,000.

If you can’t afford good converters, you can attempt mastering in the box (ITB) with decent results. As long as you stay in the digital domain, you’ll be fine.


2- Fairly ‘accurate’ speaker monitors

If mastering depends on what you hear, then you can’t skimp on these crucial items. If you thought about mixing and mastering your music, then you need a pair of monitors that reveal the true frequency response of the recorded sound. I doubt you are going to find quality speakers that can respond relatively ‘flat’ at less than $500 each piece. Thus, those $300 a pair speakers that you use for mixing will only make the mastering task a whole lot more difficult to accomplish due to the fact that you are not going to correct frequencies that you cannot hear.


However, nothing is impossible when you have good ears or deep instinct for recorded sound accompanied by great knowledge of the use of an accurate Real Time Spectrum Analyzer (“RTA”).


Warning: If you do both mixing and mastering {even with mastering speakers} you may still miss or not be able to clearly hear rogue frequency peaks and/or flaws created at the mixing stage due to comb filtering issues in the room.


3- Acoustically conditioned room

The room you use to monitor in is essentially the place where you do your critical listening and make all your compression and equalization decisions. Most people know that the room you record in should not be used to mix and master as well, thus, having one room to record and one to monitor is the ideal situation.


But, having an extra room is a luxury that many don’t have. To make things more difficult, if the room is also flawed with comb filtering issues and/or acoustical interferences, then the speakers you use for monitoring sound might be rendered from either not-so-accurate to almost useless.


Because sound always bounces on reflective boundaries, the shape of a room and even the contents in it can be a big factor on how sound will be perceived. Even your distance and angle from monitors can change that perception.


You can improve upon room acoustics with sound traps, sound deflectors and acoustic treatment or by hiring an acoustics engineer to re-design an existing room and/or build a new one if necessary. If you choose the latter, you’ll be required to invest some serious $$ in it.



Optimum mix levels before mastering
Optimum levels of a production mix prior to be sent for the pre-mastering process as suggested by Edward Vinatea in 2007. (Wikipedia.com)

To recap, there can’t be great mastering without great mixes to begin with. A good or decent mix can be mastered and the sound quality can be raised to “industry standard”, but this can never be accomplished with a poorly engineered record. It’s never going to happen, if your mix is bad, then expect disappointing results.


Realistic Mastering Results (From The Sound Process P.O.V. Only) :

  1. Bad mixes yield always bad mastering results, no exceptions, don’t waste your money.
  2. Mediocre mixes yield inconsistent mastering results. But, some significant improvements are usually achieved when done right and some results may even meet ‘industry standards’ (or whatever that means these days). Here is where the experience of the “M.E.” might save the day.
  3. Good mixes are always elevated to industry standards and sometimes results are perceived as dramatic.
  4. Great mixes meet by default “industry standards” and there is usually little room for improvement. Other than increasing loudness, the results may only be perceived as subtle.


Conclusion: Unless you never second-guess your own mixes, consistently produce outstanding mixing results time after time, built a frequency response accurate mastering room to do all this mixing/mastering work (mixtering) in the same place or location, have budget set aside to buy all the basic gear needed, and have also plenty of time on your hands to practice the art of mastering, it’s simply a lot faster and cheaper to hire a professional mastering engineer within your album’s budget today than learning tomorrow something that’s going to take a long time to sink in.


Edward Vinatea
Mastering Engineer
Website: EV Sonic Lab
Edward Vinatea is a mixing and mastering engineer who has worked with artists of the likes of Cindy Blackman Santana, John Davidson, The Shirelles, Geri King and many more.


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