I get this question a lot: What’s the difference between mixing and mastering? Sometimes a client doesn’t really know what the definition is of either term. This can be a lengthy article but I’ll try to give you a reader’s digest version. I’m gonna work backwards here so follow along.

The term mastering originally comes from the days of vinyl records, of 45’s and 33 ⅓’s. Before vinyl records though audio had to be physically cut onto a wax cylinder, in fact the term waxing was the pre-cursor to mastering because these cylinders were made of wax. Of course vinyl superseded the wax cylinders but the process remained the same, a lathe machine of sorts had to inscribe the actual, physical waveform onto the record. Recordings were typically made direct to disc, can you imagine that? Every song probably had to be done in one take, that’s something you don’t see often these days! Because of this physical, analog process of recording audio there were a number of limitations most notably including running time, dynamic range, and frequency range. What might be obvious is that there is only so much physical space on a vinyl record so of course you can only have a certain amount of musical material with regards to time. The other limitations aren’t so obvious—frequency and dynamic level, if you had too much of these in certain ways the needle would skip or bounce. This would be akin to having a scratched CD, no bueno!

But soon enough the advent of magnetic tape came. This allowed a greater freedom on the production process, recordings and masters could be made in different locations and time schedules. One of the biggest benefits though was the improvement of audio quality. It was possible to capture a wider range of dynamics and frequencies. So the audio should’ve sounded better in terms of representing the actual recording source, right? Well, yes and no. You have to take into account that the primary medium of consumption was still the vinyl record. And this is where the mastering engineer comes in to play because if a record wasn’t mastered properly the needle would jump around and interrupt playback.

In a recent issue of Computer Magazine (CM212, Jan. 2015) mastering engineer John Paul Braddock gives some great explanations as to what it means to master audio. Basically he says the mastering process is to make a track “fit for purpose.” So when you think of vinyl records that is exactly what a mastering engineer had to do, they had to make the tracks sound as good as possible on the very specific medium of vinyl.

Now let’s move forward to present day audio production. We no longer have to deal with the confines and restrictions of physical media such as vinyl and tape as a majority of music can be stored, processed, and edited in the digital realm of 1’s and 0’s. [But wait, “I’ve heard that analog sounds better than digital” you say. That’s a whole other thousand page article which I won’t go into here] Digital audio, in contrast to analog, has a great reduction in its limitations especially with regard to dynamics and the frequency spectrum; we now have much more dynamic headroom and can represent a wider range of frequencies that were previously difficult to deal with. Making audio “fit for purpose” in the digital realm is extremely easier than it was in the analog realm. Before you crucify me with that statement let me clarify that I mean “fit for purpose” here means to simply make the track work for its respective medium—the CD format—which is what I believe mastering meant for engineers years ago; do you really think people wanted to cut significant chunks of low and high end from a track if they didn’t have to? [I don’t claim to know how to master vinyl but I do know that it involves more trimming on the low and high end than does digital mastering]

Which brings me now to mixing. In fact let’s completely forget about mastering for a paragraph or two. In most musical settings involving an ensemble of sorts—whether it be a string quartet, a symphony orchestra, or a full on rock band—we as listeners want to hear the full spectrum of sound in appropriate levels. In a string quartet we want to hear the lowest cello string up to the highest violin string in some sort of pleasing balance. When the violin is presenting a melody we want to focus on that, we still want to hear the viola and cello supply their accompaniment but our center of focus should be on the melody. Extrapolating this concept to a much larger ensemble, the symphony orchestra, we want to hear the lowest tuba note through the singing range of the violin, up to the tinkle of a triangle and the shrill of a piccolo. In passages where every single player is playing something we want to hear more of certain elements than others but still in a balance that is pleasing.

A rock band has much fewer players but a whole lot more volume! But the idea of balance is still the same, we don’t want to hear a crash cymbal that’s getting in the way of the singer or a bass guitar that’s getting in the way of the kick drum. Any good conductor or live sound engineer is a mixer, they’re handling all these elements to present them in a way that’s pleasurable and artistic.

This is just one facet of mixing: blending the dynamic levels appropriately. Mixing involves a great number of other manipulations as well such as adjusting the frequency spectrum with EQ, creating space with reverb, enhancing sounds with saturation, etc. The point is that mixing involves tweaking all sorts of sound parameters so that they’re presented in a musical way. Any live musician worth their salt will tell you that you during a performance you have to constantly be listening to everybody else to ensure that you’re playing together as a whole unit, you don’t wanna be that ass hat who’s playing block chords that are way louder than the soloist, trust me. So you can think of the mixing engineer as musician of a track, they’re trying to listen to everybody and adjust things accordingly so that they sound like one cohesive unit and not a gaggle fuck of amateurs.

Now think about these live performances and where they take place. The string quartet may perform in a medium sized recital hall, an outdoor wedding, or a small upscale restaurant. The symphony orchestra will most always be in a large concert hall although occasionally you can find them in certain outdoor venues. The rock band can be found in small dive bars, medium-sized sound stages, garages, or gigantic sports stadiums. I want you to consider each unique venue as a ‘box.’ Each box is uniquely different; some are very small, others large, some have tons of reflective surfaces, others are as dry as the Sahara. Every ensemble has to adjust themselves to every different ‘box’ to sound as pleasing as possible. This is exactly what the mixing engineer does. They have to treat every recording as a different ensemble and present it as pleasing as possible.

By now you’re asking, “ok, so what does the mastering engineer do that’s different?” The mastering engineer takes every recording he gets and makes it fit into an industry standard sized ‘box.’ This box, unlike the boxes previously, is the same size no matter where you go. We call this box the Red Book standard, what you know as a compact disc. Basically the CD format uses .wav files at a sampling rate of 44.1kHz and 16-bit resolution [it’s much more complicated than this but this will suffice for the topic at hand]. Since this box is standard it should be able to fit just about anywhere, and it does! You can playback a CD-quality mastered track on a variety of formats such as a car stereo, home stereo, laptop, or into a giant club PA system and it should sound fairly consistent across the board.


I hope that this gives you a better understanding of these two processes however I’d like to leave this article on a few notes:

1. There are different kinds of mastering other than the one approach I’ve listed above. Even though we live in a digital age vinyl mastering is still alive and well! Clients also have different needs than just Red Book CD quality mastering, there are different mastering skills required for radio format, laptop/mobile device format, broadcast TV format, and so on. The main idea to retain is that each approach has its respective standard—or ‘box’—and these boxes each have their own unique restrictions and limitations. With that in mind mastering can probably best be thought of as a process that presents audio in the most sonically pleasing manner given a medium’s particular set of restrictions.
2. As with all human endeavors the skill of mastering has grown tremendously from its beginning. I’ve presented the process as a somewhat utilitarian approach but it can be used quite artistically and creatively, in fact, no two mastering engineers will apply the same processes to an identical track. That being said a mastering engineer must still be conscious of the particular limitations he is working with and also when he starts crossing the line between making a track ‘fit for purpose’ and creative expression.
3. Because of today’s technology it is quite possible—and relatively easy—to mix and master in the same step or simultaneously, I’ve heard this referred to sometimes as ‘mix mastering.’ There both exists some overlap between the two processes and some complete differentiation as well, much like there are two sides to the same coin. I personally prefer to do stereo mastering where I’m only working with one stereo track, this keeps me from reverting to ‘mixing mode’ and is a workflow that works best for me, for example, if I get a job from scratch I first mix all the tracks to create one stereo track only thinking about balance and creativity, NOT loudness or fullness. I then take the resulting stereo track and enter ‘mastering mode’ where I try to ‘fill the box’ as much as possible and bring the track to industry standard constantly comparing it to other professionally mastered tracks. To each his own.

Because this is the internet don’t take my word as gospel, read other articles and books about this and stay informed. If there are errors or questionable statements here please leave a comment in the section below so that I can fix myself and not sound like an ass.