June 10, 2011 
The words “mixing” and “mastering” are often incorrectly used synonymously and in this brief article I hope to offer an explanation of the main differences. They are two completely different processes, and I strongly advise you to keep them separate.
MIXING
Years ago, mixing engineers were called balance engineers, which I think is a better, more descriptive, term. The whole idea of mixing is to achieve a technically and artistically sympathetic treatment of the various musical elements that together convey the original intent of the composition. In other words, to make the song sound good.
The mixing process involves using all the tools that are available including panning, EQ, compression, limiting, delays, reverb, effects and a multitude of other tricks.
Sometimes, the mixing engineer will attempt to mix the song like a live performance by panning and creating space to give the impression that it’s a band playing live and together. Other types of music are geared towards a free form sound stage that has no bearing on live shows – it’s a sonic landscape that tosses out conventional performance restraints. Your music and vision will set the approach to be used.
When creating your mix you can use meticulous automation to affect each part of every track like adding momentary effects, adjust fader levels, bypass/adding effects, delays and reverbs at particular moments in the song, and changing EQ and other parameters on just parts of a track to highlight certain passages. Mixing a song can be compared to assembling a jigsaw puzzle. Other mixing approaches favor a more organic approach, particularly mixing OTB (outside the box) on an analogue console, where a ‘mix performance’ is made and parts are later edited together.
Often mixing will involve editing decisions: does that particular part really add to the song? If not, toss it. Do those multi-tracked guitars really work, or do they just create a muddy mess? Does the bass clash with the kick, or do they work well together? Those backing vocals – are they really adding to the earlier choruses, or would it help the song build more by bringing them in later in the song? Does that 24 bar intro maintain interest and grab and hold attention, or would it be better to trim it?
A Few Tips
Take your time. When you’re tired, you will not make the best decisions. I like a three session approach, with long breaks between them (hours, if not a day). Take a song, and spend Session 1 on cleaning up the individual tracks, editing out noises, squeaks, pops, guitar amp noises, vocal noises, unwanted drum noises etc. Session 2 gets all the housekeeping done. Move tracks around, set up hardware gear (if you use hardware effects) patch everything up, assign busses to reverb, delays, submixes etc. and get rough sounds on your instrumentation. Session 3 is now confined to the main mix. The Balance.
If you’re mixing the same artist’s sessions, save templates of the set up you created in Session 2 above, so that your routing and tracking layout can be reused if appropriate.
Plug-ins are not a replacement for either talent or knowledge. Don’t buy plug-ins thinking that somehow your recording and mixing will magically improve – learn to use the ones you already have, and only buy new software or hardware when you know what you’re looking for, and are sure that you can’t already achieve what you need with what you already have. Reading manuals, experimenting, and looking for on-line tutorials could save you a lot of money.
When you think you’re happy with a mix, stop. Get some rest, and listen to it the following day.
Leave automation to the very end of your mix process.
Keep different versions, and name and date them. It’s easy to let a mix ‘run away from you’ and get out of control. Sometimes an earlier mix is the best one.
Try to avoid, as much as possible, listening to solo’d instruments. Spending hours on fine-tuning a bass sound doesn’t help much when you find it doesn’t work with the guitars, synthesizer parts or drums.
Remember that every knob works anti-clockwise as well as clockwise. Although this seems obvious, constantly raising levels and applying EQ boosts all over the mix can quickly result is a harsh, brittle mess. Try notching out frequencies with EQ rather than boosting others. Always consider frequency ranges – too many instruments fighting for space in a particular part of a frequency spectrum will result in loss of clarity and space.
Have at least two, preferably three sets of monitors. High End (your studio’s monitors), El Cheapo – equivalent to what people have in their living rooms, like their TV surround speakers or stereo systems (although these are dying out) and Crap: alarm clock radios, bad car systems, boom boxes etc. And of course, your iPod or equivalent as a fourth.
Don’t worry about perceived loudness at this stage. Just create mixes that sound good, and have plenty of headroom. Advice on this varies – within a DAW -6 to -10 dbFS is a rough guide.
Listen to mixes at various levels, from loud to extremely quiet. It’s amazing how an incorrect balance jumps out at you when listening very quietly. Stand up, move around the room – unless you’re in a high-end studio, mixes done in a room with less than optimized acoustic treatment will sound different when you move around or stand outside the room.
Burn a CD of your mix, and transfer it to an iPod. Play the CD on other systems; as many as possible.
Get comments from people who favor your genre of music and who you trust. Not about the song, but what they perceive as the weak and strong points of your mix (can’t hear the bass, vocals not loud enough, guitar licks swamp everything). Family members are often not a good choice. (Most) want to be supportive, and are unlikely to tell you that you’ve just spent days producing crap.
Unless you REALLY know what you’re doing, do NOT add any effects, compressors, limiters to your mix bus. Some experienced engineers may mix with a compressor on the mix bus, but that’s because they understand the effect and know how this affects the behavior of the entire mix. If you decide to use master bus processes, when you render your mix, make another pass and make a copy leaving off master bus processing in case you decide to take the mix to a mastering studio.
Also, ignore anyone that tells you to ‘normalize’ your output mix. Just don’t. Ever. All you’re doing is increasing the peak levels to 0 dBFS along with all other levels by the same amount, and you are increasing the noise floor, as that too is increased by the same amount as needed to bring the peaks to 0 dBFS.
Similarly, don’t use any sample rate/bit rate conversion or dithering. Just don’t. Leave these to the mastering stage.
Finally, DO NOT compare your mix to completed, mastered commercial CDs. They won’t sound the same, and you’ll make yourself crazy. Read the following mastering section.
Paraphrasing Leonardo da Vinci to this context: “A mix (art) is never finished, it’s just abandoned”
MASTERING
If you’re making a demo, much of what follows won’t apply to you. Feel free to experiment with mastering yourself, but do it as a separate process, not part of your mix.
Read books, get advice on forums, talk to experienced engineers. One of the most frequently recommended books is “Mastering Audio: The Art and the Science” by Bob Katz.
Just learn what is involved with mastering. And following on from some earlier advice, buying a mastering ‘plug-in’ does not make you a mastering engineer. Again, learn how to use what you have first, and read up on Linear Phase EQ, limiting, compression, multi-band compression and loudness maximizers. Learn how to Google.
The whole point of mastering is to take a well mixed song, and add some subtle enhancements that make it sound even better. Mastering is adding sparkle and gloss to your music. You don’t fix bad mixes at the mastering stage. Period.
In the same way that a ghastly recording can’t be ‘fixed in the mix’ you can’t expect that a lousy mix can be fixed by mastering. A well mixed song shouldn’t require very much mastering effort at all, except to balance the various levels of the songs and to change the perceived loudness of the overall CD.
The songs should flow cohesively through the whole CD. Acoustic ballads are supposed to be quieter than a blazing rock track, and the dynamics within the song need to be allowed to live, and not get so squashed that listening fatigue sets in (see “Loudness Wars”) and the whole CD is a unpleasant sonic assault on your senses. The timing between tracks is important, as are the length and style of fades and cross-fades.
A mastered song should sound good on all systems. Of course, they will sound different, but if you have a song that only sounds great when played loud on studio monitors but sounds terrible played at low level in a car or on your iPod, you probably need to fix the mix first.
Mastering is a subjective process and when you go to a mastering studio, you’re really buying ears and experience.
M.E.s use specialized, often expensive, high-end equipment and monitors. M.E.s work in acoustically designed rooms and are used to listening to a wide variety of music. They know what needs to be done to your mix to get it to translate well to all listening systems. M.E.s rent you a fresh set of ears for your project and can help to correct any slight deficiencies that slipped through the mixing process, often because your room is not flat and there will probably be consistent imbalances in the frequency handling within your mixes which can be corrected.
Frankly, a M.E. doesn’t have an investment in your song or you as an artist, and therefore can examine your mix solely based on what will sound good and not be influenced by what your drummer, bass player or singer might like.
A simple example: in your mix room, maybe there is a room mode, which you may not be aware of, at around 250Hz of about +2 dB. This causes you to think that your low end at around that frequency is fine, but in fact at around 250Hz your mix is 2 dB light. A good M.E. will hear this, and make the right EQ change.
Unfortunately, any element you address in the mastering effects other parts of your song whether they need it or not. This can be avoided by using mixing stems, but that is beyond the scope of this article. This illustrates another reason why your mix should be your focus – mastering is adding some fairy dust, not polishing a turd.
A Few Tips
I often hear from fledgling artists that they can’t afford a M.E.
Wrong. You’ve invested in recording gear and instruments, endless weeks of writing, rehearsals and recording, even more hours of mixing, and you now want to toss it out there to the world?
Suppose you’re selling your car. Do you just show it ‘as is’ or do you invest some time in an effort to fix small issues, wash, polish, vacuum, clean the windows, treat the upholstery? You want to present your product in the best possible light to your audience: a car buyer or a potential fan of your music.
Some mastering studios are expensive, but you don’t have to use them – there are many mid-range facilities staffed by experienced engineers with great ears who are not that expensive. Some charge by the hour, some by the song, some by complete CD project. Relatively, all but the most expensive facilities are within the reach of most artists. Maybe budget $400 – $1,300 for a good mid-range facility for a 10 song CD – but the price varies substantially depending on your location.
Think about pre-mastering consultation. Take a couple of your most representative mixes, and buy an hour or so at a good local mastering service. Your aim here is not to actually master anything. Just turn up with your mixes, and sit with the M.E. and listen to them. Pick the M.E.’s brains – ask him/her for comments. How is the EQ? How do the spacial elements hold up? Too much reverb on certain instruments? Is there some mud or HF ‘fizz?’ How’s the definition? Any avoidable distortion present? Phase issues? Mono compatibility? The key question to ask: “Do you think my mix is ready for mastering, or should I try again, and on which elements should I concentrate?”
The insights you get at such a meeting might help you immensely. You might decide to mix your songs again, but now you have some data to go on. You might choose to make some more changes in improving the acoustics of your mix room. Or the M.E. might tell you that it all sounds really good, and he can do a great job in mastering for you.
I usually suggest avoiding online mastering services, although some are very good, and you can certainly use them to compare different facilities later. I believe that the benefits in attending mastering sessions outweighs the slightly increased cost. You will develop a relationship with your M.E. and you’ll pick up lots of tips on how to make your mixes better. Listen and be gracious – you might decide that this particular M.E. isn’t right for your project, but you gain experience. You can then continue to audition mastering facilities until you find one with which you’re comfortable. Relationships are all important in the music business, and remember that a good M.S. is a knowledgeable person who, if s/he likes you, could be another great connection to have.
To find a good mastering engineer, ask around in your area. Ask studio engineers. Ask other artists. Even if you have to drive a few hours, go there in person. Talk to M.E.s on the phone. Look around for M.E.s that have cared enough to put helpful articles on their web sites describing their services and explaining the various options which they offer.
Additional reading:
soundpropaganda 
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