The last line in the process before a song or album is released. It is the mastering engineers job to ensure that the media is ready for release in the format intended and to the standards of the respective format.
There are many reasons that we need mastering. For example, when an album is made, it’s quite common for each song to have it’s own “sonic palette” or sound design. Similarly, groups of songs might have been recorded or mixed in different studios, and quite possibly by different producers – each with their own set of “ears”.
A side effect of a using different studios for recording and/or mixing is that irrespective of the equipment, every room has it’s own acoustic “sound”, and a mix engineer will make decisions based on what they hear. This could result in ‘resonances’ or ‘troughs’ in the frequency spectrum, causing the engineer to inadvertently boost or cut a particular frequency to compensate due to what they’re hearing.
When grouped together as a single body of work, the album may sound disjointed and inconsistent due to each song’s disparate creation environments. Plus, they might also have vastly differing levels of “apparent loudness” depending on the style or genre of each song.
The ultimate aim of mastering is to give the body of work a cohesive listening experience – while always maintaining the mix’s original integrity.
Mastering is a process that involves both objective and subjective listening.
Every mastering engineer has their own “style” and personality that they’re renowned for. However, an objective point of view is generally taken before any subjective processing is applied.
Objective issues relate to aspects of the mix that are seen as imperfections. In most cases, these are not down to personal opinion, but rather, unmistakable blemishes that weren’t apparent or intended at the time of recording/mixing such as signal or data corruption. They could also be things that were caused as a result of the recording/mixing environment, such as poor monitoring.
mono / out-of-phase / widening, lacking definition in bottom end mix is jumping around madly, unnatural changes in volume, unwanted noise/hum/glitches, frequencies that ‘stick out’, bass / top end imbalance, stereo imbalance, too dull / bright, muddy mix, hidden vocal, quiet overall
This objective treatment can be thought of as the corrective stage.
EQ, compression, multi-band compression, parallel compression, exciting, stereo widening/narrowing, and limiting are amongst the tools used here, some very sparingly, others not at all. The thinking here is to use these tools only if absolutely required, and when so, with a most delicate of touch. Again, this is not the time for aggressive processing – what you want to do here is to add some *sparkle*, but NOT alter the mix – one must always keep that in mind.
There are rare instances however, where mastering is needed to rescue a poor mixdown, or restore old mixes, in which case more heavy handed treatment is called for.
The is the part where the mastering engineer’s personality comes into play. It is where they will apply their personal judgement to the colouration and balance of the audio.
Much like a songwriter’s style – what a mastering engineer “hears”, is what defines their character.
This is where the mastering engineer adds their value – and that value is entirely a matter of opinion – you may either like it, or you may not.
I believe this process should always be two-way conversation between artist and engineer, but sometimes creative opinions can differ, and may not always resolve. It is for this reason that some artists/producers/labels will take the time to seek a mastering engineer that understands their style and ‘fits’ their music – and then nurture that relationship.
After all sound processing has been applied, the final step is to optimise the audio signal for the intended output format.
radio, tv, wav/CD, vinyl, cinema, gaming, mp3 (hi / lo) Mastered for iTunes, mobile phones, PC speakers, laptops.
This largely objective process, is to ensure that the mix sounds as close to the intended recording, compensating for any added colouration that the medium it is being rendered to may impose on the recording, due to its own physical limitations.
For example, low bit-rate mp3s add a certain “sizzle” in the top end, so if the recording has a lot of high frequencies present, this will exacerbate that sizzle effect, so you may choose to compensate accordingly before rendering to that format.
Similarly, vinyl has a lot of physical issues one must consider. For example, anything below 300Hz should generally be in mono to ensure the cutting needle is able to cut the necessary groove. Any bottom end that is panned left or right, or even out-of-phase, will cause problems and not be able to be transferred to vinyl. Each side of vinyl also has limited duration, and if mastering for a long side, you may consider gently increasing the top-end towards the end of the recording, to compensate for the decreasing high frequencies you’ll hear on the inside tracks of most vinyl albums.
Another element that is oft debated by mastering engineers everywhere, is the stage that ensures your recording will sound as good as, if not better than (read: loud), other music played alongside it. This involves what is called “apparent loudness”.
This desire to sound louder than other recordings, started what is now known as the “Loudness War”.
To pinpoint its exact beginning is difficult, but it was around the time recordings became widely available for purchase – around the days of vinyl. The war element of this is achieved through active participants performing in competition with each other trying to make recordings sound as loud as possible, and is the musical equivalent of an evolutionary arms race. It was borne out of the psycho acoustic phenomenon that occurs when you listen to two or more pieces of music that have different volumes compared to each other. The phenomenon is that the louder piece of music always sounds better than the quieter one (up until the threshold of pain).
New methods of imprinting a hotter signal on analog mediums kept evolving. Digital recording technology didn’t have the physical limitations of vinyl and tape, and could offer louder and brighter recordings from start to finish.
This process however, has it’s drawbacks, in that it can cause the music to sound “squashed”. The easiest way to explain this to think of the apple in vacuum packaging. If too high a vacuum is applied, the apple will simply crush , and while it’s still inside this neat little package, the apple no longer resembles the initial recordings. This is a personal choice – and every mastering engineer will have their own personal philosophy on it.