Understanding the audio mastering process

Audio mastering is a final procedure where your stereo music mixes are committed to their final release medium, this could be a CD-R pre master ready for duplication, a DDP (Disk Description Protocol) or correctly encoded audio files. In any event it is the mastering engineers job to ensure that the music is equalized and processed in a way that ensures it will translate across the widest range of reproduction sound systems. A mastering engineer should have a long standing history of professional work within the music/media industry and should be highly experienced. He or she will be able to confidently decide the best processing (if any) that should be applied in order for the music to sound as good as possible. In addition the engineer can work with the fades, spacing, leveling of tracks and increasing perceived volume if required. Finally the music should not suffer from defects such as pops, clicks, bad edits or other sonic glitches.The medium for duplication or distribution should also be error free and quality control should be applied to ensure the client receives the best product possible. Mastering usually works with the final stereo mix downs but can also take the form of stem mastering. This utilizes groups of instruments (i.e. drums, bass, guitars, vocals) to further enhance the result. Mastering is very different from mixing which is where the multi tracks or sequenced elements of the music are individually equalized, compressed,  effected, automated and leveled.  
 
Why get your audio mastered ?  

There are numerous reasons to get your music mastered. Long, tiring mix down sessions mean that details can be missed, it may be that you miss a click or a pop in a mix and this is best removed before it is heard by your listeners. Some mix down environments may not benefit from high resolution, large format loudspeakers in a acoustically treated room. This means that there can be sonic inaccuracy that needs correction before release. Mastering engineers also offer a set a fresh ears with renewed perspective to a project which the musicians and producer may be overly intimate with. This can clarify and resolve sonic issues in a subjectively useful way. The mastering engineer will be expert in working with stereo 2 track material and have a skill set and hearing acuity which brings great value to a project. Processing stereo 2 track mix downs requires a very different approach than a mixing situation. An experienced mastering engineer will be fully aware of the advantages and disadvantages of any applied processing across a stereo mix and will seek to maximize subjective improvement whilst minimizing any side effects. Good judgment is the core of the mastering engineers job. This is closely related to high end, high resolution monitors, amplifiers and acoustics which create the fertile ground for good decision making.  
 
Why hire a professional mastering engineer?  

On the internet forums you can occasionally find people who want to offer mastering for free but this is not professional mastering. Professional mastering engineers spend years on the acquisition of skills and reference grade equipment. There is no short cut to this and as such you need to be wary of certain abuses of the mastering profession online. If you want quality results “free mastering” and websites that are purely graphics and text based should generally be avoided. Sites that do not show the room, the speakers, the equipment, a clients list, engineering back ground are rife and you have to ask yourself why such important details are missing. This is all common sense really. A professional will be able to bring something new to your project and with serious reference equipment will be able to listen deep into your mix downs and make confident and positive correction where need be. A beginner, student or someone who is ill equipped can easily process your music in a detrimental manner and mastering is not the time or place for experiments, learning on the job or beginners. A professional mastering engineer will add value to your musical releases without leaving anything to chance.  
 
How do I prepare for mastering?  

When you bounce or export your mix downs out for mastering please bounce at 24 bit resolution and at the existing sample rate of your DAW session. The files should be stereo interleaved .wav or .aiff files. You can also bounce to 32 bit but their is no sonic advantage over 24 bit for the purposes of mastering. Before you bounce your mixes ensure you bypass any limiter plug in on your software master bus. After doing so ensure you check for any clipping (signal peaks that exceed zero). If you do see clipping, rather than adjust your mix gain structure please simply pull down the master fader by the amount that is needed to resolve any occurrences of clipping. You can then export the files at 24 bit resolution. Files should be named with the track and artist name and a date which is useful for all to know.Files should be zipped up using Winrar, Winzip or Stuffit Expander and uploaded using a suitable online file transfer website. This data compression is loss less and so does not affect the audio quality in any way and it has the advantage of protecting the data integrity when the audio is sent online. It is also a good plan to prepare a .rtf text document with the track running order, track name, artist name(s) and any sub code information that will be inserted into the final medium such as ISRC codes. This should be sent to the mastering engineer with the audio files.
 
How do I choose the mastering studio?  

Mastering operates in 2 main ways, attended sessions and online mastering. The former means you need to attend the studio and sit with the engineer and listen in and make comments as you feel is required for your music. Some people like this way of working but it is more expensive and can be a little daunting listening to your music on a large and unfamiliar reproduction system. Online mastering is a much more cost effective and you still remain in complete control of your musical project as the mastering engineer will send mastering preview files so you can hear the music for yourself in a familiar environment. For online mastering I suggest making judgment on a site based on seeing credible information and actual pictures of the equipment that resides within the studio. This way you can easily rule out bedroom operators and the inexperienced posing as mastering engineers. Apply your judgment, check all the information on the site and ask yourself if you feel as if there is sufficient information to be able to trust the engineers experience, tools and previous work history. Many online mastering studios offer a free mastering sample, this can be a great way of hearing the quality of work, ruling out the charlatans. You can also try calling the mastering engineer and getting a first impression, ask about equipment choices, how to proceed and get a feel for the competence of the engineer.  
 
What is mastering capable of doing ?  

Mastering is a final procedure and normally works with stereo interleaved final mix down files, (unless you are choosing stem mastering which uses instrumental groups) this means that all processes are stereo ganged. This means that there are some mix issues which are not possible to resolve during mastering because of the inherent limitation of the stereo 2 track nature of the work. For example if you have mixed your bass too low in the mix it will be difficult for a mastering engineer to raise the level of the bass without raising other central elements in the mix. (i.e. snare /kick drum, vocals). These issues relate to mix down and it is here where they are best resolved. Some mastering engineers will offer basic mix advice if you require it as long as you are serious about proceeding with the work, this is an added bonus of online mastering as it can be addressed prior to the time of mastering if the mixes are sent in for an appraisal before mastering commences. Mastering is normally capable of adding space, depth, punch, thickness, perceived volume increases, warmth, air (sparkle) and other global tonal changes, to a mix. Stem mastering affords additional scope to target specific problems and further increase the subjective enhancements and apply an “expensive” sound to the production.  
Barry Gardner is the sole mastering engineer operating SafeandSound online mastering. An uncompromising online mastering studio with affordable mastering rates so all musicians, bands and producers can experience the benefits of professional mastering on their projects. Visit the site today for much more information on the subject of audio mastering.  
 
Is analog or digital mastering best?

I offer a personal opinion related to this question. Personally I have found that a combination of both analog and digital processing produces the best results in mastering. There are some techniques that analog processing can perform better than digital processing and vice versa. A mastering studio is not complete unless it has a combination of the 2 which seem to compliment each other very nicely. Ultimate results can only be realized by the use of both technologies in the vast majority of cases. However it can also be the case that occasional jobs benefit from the use of one or the other and this decision is reliant on the experience of the mastering engineer and the sonic goals at hand.
 
Does the client have a lot of input in the mastering?

This varies from job to job, some clients provide a list of pointers and instruction on a track by track basis and some clients just allow the mastering engineer to do his work and do the best for the music with a completely fresh and unhindered approach. Of course there are some jobs that have a combination of the 2 with some basic guides or sonic references for the engineer to work to.  

Barry Gardner operates SafeandSound Mastering, a mastering studio with a full complement of both analog and digital mastering equipment. The studio uses high end, full range, reference grade monitoring in an acoustically controlled environment.Offering surprisingly low rates for premium results. Visit the website today by clicking on the highlighted word above.