What is Mastering and How is It Different From Mixing?
As a mastering engineer, I’m often asked to explain the difference between mixing and mastering. They both include volume level adjustments and EQ. They both aim to make a good blend of sounds and proper presentation of music for your listeners. And you can easily add plug-ins on the master output in your DAW, which presumably means you could simply address the final “master” output of your audio work while in the “mix”. So why not just call it all mixing?
To answer this question, first, let’s think about what we’re trying to accomplish when we’re mixing. Mixing is the portion of your audio work that involves the blending of various recorded or programmed tracks within a single song. It requires making individualized adjustments to each track to ensure every sound has its own particular place within the song.
During mixing, you’ll likely consider the overall flavor or character of the song that best represents your artistic vision. And, of course, watching for those minor details within individual tracks to ensure unwanted noise is cleaned up, timing between elements is spot on, and pitch adjustments have been applied.
Where does the overall loudness come in to play?
You might believe you need to address it while mixing because you want your song to be loud and clear on all listening devices. But, if volume level were part of the mixing work, then it would also be true to say that your song only sounds correctly mixed when someone is listening with the playback volume at a certain level. Obviously the volume setting has very little to do with sound blend and artistic flavor of a song, so therefore this aspect should not be considered part of the mixing work.
That’s where mastering comes in. Mastering is the portion of the audio production that deals with the overall presentation of sound after all the mixing work has been completed. It’s the step that addresses issues not related to blending individual parts together or creating a particular characteristic sound that identifies an artist or band. Mastering has to do with sweetening or enhancing the song’s final mixed sound and ensuring the most optimal playback for all listening situations. Both of these require a completed mix first.
Think of the difference between mixing and mastering like making a cake. When you mix the cake batter you carefully measure out the various ingredients required to assemble a particular flavor of cake you want to make, including any special adjustments that match your own subjective taste preferences. And here the words “flavor” and “taste” work well metaphorically since they fit your sense of taste as well as artistic musical preferences. Once the cake ingredients are all mixed together, it’s still not finished.
You have to bake it, and you may even have a further step of frosting it. Neither of these steps is done during mixing. That would be absurd. Similarly, saying that baking and frosting a cake is part of mixing ingredients also doesn’t make any sense. We can see from this analogy that there are clearly defined steps in the creation of something that combines multiple elements to produce one final integrated outcome. Some steps deal with the combining of individual elements and others address the overall combined product.
So Why Can’t I Simply Turn Up The Volume Level In The Master Output Channel of My DAW and Call It “Mastered”?
If mastering is a process involving the overall combined mix and not the individual elements within the mix, and it addresses the overall loudness of the song, which we agree isn’t technically part of what we’re aiming for in mixing, then why can’t we simply add a compressor or limiter to our master output channel and push the volume up until it sounds loud enough and say it’s now been mastered? While it’s true that in some instances this actually may be sufficient if you’re not careful you can ruin a good mix this way. There’s typically a lot more to mastering than just increasing the master volume level.
For starters, there’s the psychoacoustic effect. Your ear hears different frequencies of sound with differing efficiencies at different volume levels. For example, your ear does not hear deep bass sounds well at low levels, but suddenly they become quite noticeable at higher levels. In contrast, upper midrange tones you hear very well, even at relatively low volumes.
So, if you create a mix with a nice blend of bass, midrange, and treble sounds and then raise the master fader several deciBels, you may notice it introduces an imbalance in the sound, even though all you did was raise the overall volume. This is a result of the physiology of human hearing. When a mix is being properly mastered, the mastering engineer will take the psychoacoustic effect into account and make EQ adjustments to maintain the desired balance that you worked so hard to create in your mix.
There are other adjustments applied in professional mastering work, such as dynamic range adjustment appropriate to the genre of music, image width enhancement to open up the sound or enhance the width of your panning in the mix, intro and outro fades that may need to be readjusted once the track has been boosted to its final playback volume level, digital noise cleanup related to the discrete nature of digital sound sampling, and other details as well.
It’s true that in some cases when you simply apply a limiter to the master output channel or have an automated online mastering system boost your volume levels it may actually provide a good enough representation of your original mix, even at the full volume level. But, in instances where it really matters, like if you have a chance to submit a song for a contest or to get picked up by a label or a publisher might want to pitch one of your songs for a streaming television series, or if you otherwise want to make sure you’ve created the best possible sound for your song, you should make sure it is fully mastered with consideration to all necessary elements.
Using our analogy again, make sure your cake is properly baked and professionally frosted when you plan to share it with someone important.
How Do I Know When I’m Done with Mixing and Ready to Begin Mastering?
Knowing the difference between mixing and mastering helps us understand that when we want the best possible results we should properly master a fully completed mix. So, how do we know when the mixing is done and the mastering is ready to start?
In some ways, this is the easiest question to answer. The simple answer is if you feel like your mix represents your desired balance of sound and character of musical presentation, then it’s done. At that point, you proceed with the audio mastering step to smooth out those final technical bits and pieces as part of the whole-picture effort. But, we need to remember our analogy of the cake. You can’t hand a mixed bowl of cake batter to the baker at the oven and say, “Please take some of the egg out of this while you’re baking it”.
On the other hand, you can say “I think it may not be sweet enough” and the baker at the oven may answer “not to worry, we’ll frost it after baking it and that will make it taste perfect”. By this I mean consider which aspects of your sound must be dealt with at the level of the mix where you can address them within the individual tracks of the song, compared to other elements that can be very nicely refined as part of an overall sound enhancement and sweetening process. When in doubt, hire a professional mastering engineer and ask him or her for advice. It never hurts to ask for help from a professional.
About The Author
Erik Veach is the owner and lead audio engineer at Crazy Daisy Productions, providing mixing, mastering, and sound editing services since 2001. He is the original pioneer of automated intelligent mastering systems, introducing them for use in professional music production in 2003.