Why Mastering is so Important

by Feb 2, 2019Blog0 comments

Fresh off the heels of January 2019, Winter NAMM was an amazing experience this year with lots on the horizon.  While there are still F.U.D. articles floating around social media and the web asking whether the music industry is dying, this year’s NAMM convention was a clear indicator that the industry is only growing.  As more and more people discover the power of music and audio, I’ve been consistently running into questions about mastering and whether it’s better to self-master or send out to a professional mastering engineer (M.E.).

I’m not going to just claim that sending out to a professional is a golden, universal rule you should blindly follow.  Though there are a number of benefits over self-mastering, I’d like to paint a better picture of what mastering does for those of you who are curious about the art of mastering. Hopefully this article demystifies that process so you can decide for yourself what is best for your situation.


Most people have come to understand mastering as when an engineer applies further audio processing to the mix. To be technically correct, however, that is a pre-mastering stage.  There are other operations that go beyond processing audio, but let’s dive into what mastering can provide sonically for a mix.

Making an Impact

Dynamics processing at the mastering level is not just about achieving loudness but balancing loudness with character.  The character can be anything from how the audio gets shaped by the response of the dynamics tools to add bite or soften the attack in comparison to where the meat of the audio sits.  The goal is to balance “loudness” with “impact”. Push dynamics tools too far and, just like an elastic band, it will break.

Loudness Wars

The subject of loudness wars is a deep one, and mastering for the new age of digital music means having a more in-depth understanding of what loudness is and how it’s perceived in various measurement methods. Perceived loudness is a subject that still carries some artistic merits, depending on the genre and style of music, informing just how “squashed” or “dynamic” the final master should be to still sound pleasing and be competitive.  

Not every song “needs” to hit the exact same loudness target and many may actually suffer negatively from either being overly processed or left sounding unfinished. A good mastering engineer will know when to rely on industry standards and make a creative decision to adhere more strictly or more loosely to best serve the song, not just follow what competitors are doing.


Equal Loudness Contour is a term that is based on the study of how the human ear receives and shapes the sound we hear across the frequency spectrum.  Mastering Engineers spend a good majority of their time sculpting the shape or contour of the mix to achieve the best balance for a given song. 

These EQ-based moves tend to be broad strokes as opposed to surgical boosts or cuts. This doesn’t necessarily mean all mastered music will have the exact same contoured master as the next song; it all depends on both the mix and the intention (of the artist and the mastering engineer).  Mastering engineers are focused on where the energy of a song is placed and where to enhance the frequencies to achieve harmony amongst the full spectrum for the most pleasing listening experience.


These pre-mastering processes often have both a creative and technical goal to achieve.  The priority of a professional mastering engineer is to do no harm. This tends to translate to them being transparent in what they accomplish.  A second priority is to enhance and provide focus to the mix.

A professional mastering engineer will have studied and kept current on changing industry standards for all the outlets a deliverable may be distributed to and leverage that knowledge to make educated, creative decisions.  

This can include tuning the pre-mastering process to achieve the best quality encoding of lossy-compressed formats like MP3, AAC, and others.  While it is typically an unspoken rule that mastering engineers want to provide a single “master” for a song regardless of where it’s destined to go to in the massive marketplace for music, there are inevitably some circumstances where alternates may be designed.

Some engineers may apply specific processing (perhaps as an optional service) such as mastering specifically for a vinyl release.   Another possible fork could happen when sending out to duplication or pressing facilities for Compact Disc. There are a number of sub-code and digital markers for features specific to CD’s that could affect the playback, such as Pre-Emphasis (similar to what Vinyl masters undergo with what’s called the RIAA curve).  A good mastering engineer will take the time to understand your market’s needs and cater to the best delivery formats for that market.


As if that wasn’t head-spinning enough, there are a plethora of non-audio related tasks that mastering houses may offer these days that can help with providing the best end-experience, and all of these have to do with logistics and getting the music into the marketplace.


Metadata is the keyword of the day and the gatekeeper to future-proofing your content.  With so many avenues for generating revenues streams from music that go beyond just uploading your song on Bandcamp or Distrokid (both are great platforms in their own right), Metadata becomes ultra-critical for publishing houses, synch-licensing agencies, and labels.  To exemplify this, Distrokid has recently expanded it’s metadata entry abilities by allowing authors to submit deep “liner notes” credits via it’s new beta Song Credits & Liner Notes service.

Album Artwork

Have album artwork?  Most portable music file-formats accept album artwork injection.  While services like Distrokid and Youtube may provide tools to upload custom content covers, those are individually specific to those platforms and that doesn’t propagate to other places your distributor may send to.  Mastering houses that utilize specific tools like Wavelab, or HOFA-CD-Burn & DDP Maker, can also inject album art and more, along with providing proof sheet PDFs with all of the critical information about a given project.

If you’re looking at self-mastering, these tools provide more non-audio mastering functionality than many common mastering suites such as iZotope’s Ozone Advanced (although their DSP certainly is well known).

ISRC Injection

International Sound Recording Code is another critical non-audio aspect that mastering engineers may wrangle.  Some mastering houses may have their own ISRC Registrant codes, but you can apply for your own (traditionally, the ISRC code should be issued and owned by the copyright holder of the sound recording).  ISRC is the digital marketplace equivalent of a UPC barcode. The ISRC is how digital music outlets identify who the product belongs to.


Transcoding is like transcribing.  In much the same way as a scholar would translate a book into a new language or make a copy by hand, mastering engineers must prepare the audio to be translated into various file formats or codecs.

As touched on above, there is much more that goes on under the hood when converting a full, high-resolution uncompressed audio file like a Wave (which can be hundreds of megabytes or more), than simply saving as an MP3.  Mastering Engineers pay critical attention to how to optimize audio to retain the most fidelity to lossy formats like MP3.

As the term lossy suggests, in order to achieve the data compression that makes your average MP3 as much as 1/10th the file-size of the original master, tons of data that describes the audio gets “thrown out”.  If you’ve ever noticed horrible playback quality on your Soundcloud upload, you can begin to imagine just how difficult it must be to optimize for this transcoding process.


Want physical pressings in CD or vinyl?  Mastering engineers who deliver for these formats will have an intimate knowledge of what these formats need to best prepare the content for delivery.  DDP is an industry standard format for submitting an audio project (album, EP, or single) to a duplication or pressing facility. As I touched on earlier, vinyl requires some further preparation, and this is where mastering engineers need an understanding and working knowledge of the RIAA Curve to create a separate vinyl master that retains the best fidelity, as vinyl presents several physical and performance limitations that the various audio projects can present.


Hopefully, you have a slightly better understanding of why mastering is so important.  Sending out to a mastering engineer won’t be necessary for everyone. You may not be able to hire an industry veteran who charges hundreds of dollars per song, but also may not need any of the specific services they offer.  If you’re on the fence about considering hiring out, or struggling with learning it yourself; the best way I can think to describe a professional mastering engineer is this:
Mastering engineers are the framers of your audio masterpiece.  A mastering engineer is the one who takes the raw art – the canvas upon which your art is painted, and prepares it for the world.  Framing is an equally important aspect of the final presentation. Like a framer, a mastering engineer will make careful creative choices to present the art-piece in the best way possible.

A framer will utilize matting to help focus the art-piece to draw emphasis to what they feel is the most important part of the canvas, hiding the edges where often the painter may have left imperfections that can potentially pull the audience away from experiencing the message the art is trying to get across.  A framer will consider what gallery the piece is being displayed in, and what art may be displayed next to yours as well as the lighting conditions of that environment in order select the proper matting materials, frame type, size, shape, color, and finish. All of these are intentional creative choices that impact how the end-viewer will experience that art piece.

A mastering engineer does much the same.  We make creative decisions about where the content may end up (often many places), and “frame” the mix with the use of precise creative audio adjustments to the dynamics and EQ (sometimes using saturation and distortion and other modulation effects) to squeeze every ounce of optimization out of a given delivery medium’s format without sacrificing quality or intent.

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Do you have a mix you’re stuck with?  Are you considering finding a mastering engineer you can trust?  Send me your mix and I’ll provide a free mix critique. I also provide free test mastering previews!

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Was there something I missed or left out?  What struggles have you faced?  Have you found a mastering engineer that’s helped you achieve a new level of quality?  I’d love to know what experiences you’ve had with mastering, so leave a comment below!