Mastering: Basic Music Mastering Tasks
To sell your music for commercial use, it is critical that you master your music tracks properly. We are increasingly engaged in licensing activity where the music is heard "as is," without embedding it into a production. This includes usage for commercial background music services, as well as for the production of audio CDs. We must count on each of you to double-check that each track is properly mastered without undue silence at the beginning or end, with no clicks or pops anywhere within a track. If we discover these flaws, we are unable to export the track for any deals in the future, which will lose you $$$.
While it’s now true that anyone can create a good mix with almost any gear it’s still easy to mess up a mix and betray the fact that you didn't spend thousands at a top studio. Frustratingly, the same errors crop up time and time again and it’s these that separate the greats from the not-so-greats. Mastering can be the stage where the final layer of magic is applied, but mastering is always the stage where any mix problems will be ruthlessly exposed. Think of mastering like holding up a big magnifying glass to your tracks… there is nowhere to hide!
If you need a software tool to help you fix these kind of problems, you can download an evaluation copy of Cool Edit 2000 from http://www.audiosparx.com/software. Cool Edit 2000 is a great program for doing all kinds of basic mastering functions including removing clicks and pops at the start or end of a track, removing excessive silence at the start or end of a track. The evaluation version is not time-limited, and does not expire; you simply have a subset of the available features (you choose which) each time you start the program. This includes checking the following things:
- Make sure all tracks have only 200ms (1/5 of a second) silence at the start. While it does not have to be exactly 200ms, it should only be a fraction of one second at a maximum. This ensures that there's not an undue silence at the start of each track when it is included on a CD or in an in-store playlist.
- Make sure all tracks have no more than 1 or 2 seconds of silence at the end, so that there is not undue silence at the end of a track when it is included on a CD or playlist. Ideally there should be only between 200 and 500ms silence at end.
- And please, REMOVE UNWANTED CLICKS OR POPS at the start, the end, or anywhere in the middle of your tracks.
- Don't turn up your mixes too loud. A common practice when mastering tracks for radio play is to boost the volume up above the 90th percentile in the volume range. DO NOT DO THIS FOR TRACKS YOU UPLOAD TO AUDIOSPARX!! Keep your mixes below the red line, or with occasional peaks crossing the red line, but not persistently above the red line. We see many young Hip Hop composers, and young composers in general, make this mistake.
- Don't set the volume too low. If a mix is too low, say mixed only around the 20 to 30th percentile in the volume range, it is difficult to hear the nuances of the music without having to turn your computer's volume control way up. This can easily make clients think there is something wrong with your tracks and they will bypass it just because it is mixed too low in volume. Try to keep your mixes, at the loudest point in the song, in the 70 to 100th percentile range with occasional very brief dips into the red zone.
- 15, 30 and 60 second tracks - Always make tracks of this duration be EXACTLY 15, 30 or 60 seconds long. Tracks of this duration are generally used for commercials on TV and radio, and commercial spots are always generally sold in exactly 15, 30 and 60 second lengths. If your track is a few seconds too long, that may not seem like much, but then the client has to figure out how to change the track in order to use it for their commercial. Most clients don't have the capability necessary to fix a track to shorten its length without making it sound either chopped or having a quick fade, both of which can be undesirable. So, they may skip your track just because it is a few seconds too long and purchase another different track that is exactly the length they require.
Additional Common Problems
- Don't mix the track's volume too low or too loud. If you mix the volume too low, it is hard for anybody to hear it without first turning up their stereo system. This can easily make it seem to the listener like there is something wrong or inferior with your track, and they will usually skip it just on this basis alone. So, turn the volume up in the mix so that it is dipping only occasionally into the red zone, or just under the red zone, so that the details of the track can be easily heard without having to turn up the stereo, yet not so loud that it is constantly in the red zone, which can introduce undesirable audible distortion in your track. A big mistake many artists make is cranking the volume up WAY too loud, constantly riding into the red zone, thinking that this will make the track plenty loud when played back, which it does, but this can and will also create obvious audible distortion. So, don't do this -- doing this will just damage the commercial potential of your tracks. We will generally immediately bypass tracks that are mixed too low or too loud when playlisting tracks on RadioSparx or sourcing track lists for client production projects.
- Don't mix the Bass and Kick too loud. Without doubt one of the biggest errors we see is the low frequencies being pushed to a needlessly loud level. This is a misguided practice for one main reason – overly loud bass eats up headroom and makes it harder to get a loud master. At the mastering stage an overly loud bass can make it very difficult to achieve the holy grail of “LOUDNESS” as the highs and mids won’t get to be that loud before the bass or kick starts clipping or distorting. Not cool if you want your track to be as loud as the vast majority of commercial releases. So why do so many mixes have this issue? When speaking to people who have submitted tracks where the bass has been mixed too loud the answer is either, “We wanted the bass to sound really big in the club” or “We didn't realize it was so loud”. To deal with the first point, if you are making music that will be played in clubs remember that club sound systems will already be designed and calibrated to make sure that any bass frequencies are amply represented. Mixing should be a time to balance levels, sculpt tones and get your music sounding good, not loud. The second point, however, needs a slightly more complex answer…
Bass frequencies are hard to accurately reproduce in listening environments and if it was easy to fix then this mistake wouldn't be a common one! However, the best thing you can do is ensure that you have the most acoustically neutral mixing environment that you can get. It is not possible to overstate the importance of this. You can have the latest plugins or most expensive hardware but if you’re using them in an untreated room then you’re mixes are always going to struggle. You can achieve this through use of acoustic products such as diffusers, absorbers, and bass traps, and you can even use well placed blankets and duvets if money is tight. Get used to your space and listen to plenty of reference tracks.
Using acoustic products will not only improve bass reproduction but, done properly, you will notice improvements in stereo imaging and reproduction in the highs and mids. Another way to improve here is to periodically check your mix through a frequency/spectrum analyser. It may take a bit of time to get used to an analyser and learn what you should be looking for but the rewards can be huge. Again, listen to plenty of reference tracks while watching the analyser and start to piece together how the producers and mixers got their track to “look” like that.
- The mix disappears when checked in mono. Hang on, mono? Didn't that die in the 1970's?? No! Many places and items use mono – stadiums, clubs, shops, TVs, cell phones… the list goes on. Lots of electronic items use mono speakers as a convenience or for cost reasons, but systems in big spaces will use often use mono to ensure an even sound across a location. As part of the mastering process I’ll sometimes check what I’m doing in mono and when I hit that button elements of the mix just disappear! So why does this happen? The main reason I've encountered is misuse of stereo widening effects. Many widening effects work by adjusting the phase of a stereo signal (phase is too big a topic to try to explain in this article but there are good articles and resources all over the net) and when pushed to the extreme the signal disappears in mono.
This one is easy – check your mix in mono! Nearly all DAWs have a Mono switch on the master channel (if you lack this function then Brainworx have a great free tool called BX Solo which allows summing of all incoming signal to mono, among other things). Quickly checking in mono will immediately tell you if anything’s wrong and you can do something about it there and then. If the offending cancellation is coming from a part that has been recorded in from a real world stereo source then you can use your mixer’s polarity inversion switch to counter act. Another thing that may help is to grab one channel of the stereo recording and nudge it forwards or backwards until it starts sounding good. This approach can also help if you have a multimic’d source like a drum kit. If the offending cancellation is coming from an effect then ease it off until it’s sweet, or find an alternative effect. Bear in mind that not all stereo widening effects are equal and you may get results close to what you want without phase cancellation using a different plugin. Experiment and see which works best for your track. Phase monitoring plugins are also available to help give you a quick visual aid with any phase issues.
- Mix is too bright. Making audio sound bright is a big temptation when mixing. Lifting up the high frequencies can be a great way of adding extra sheen to a production and making your music sound “big money”. Also, human hearing is particularly sensitive to frequencies between 2kHz and 5kHz, and it is a great temptation to load up this area with information in an effort to make parts stand out or have presence. But what can happen is the highs are inundated with extra additive EQ, extra energy and extra bite and it all turns into one big spiked brick of harshness.
Subtractive EQing is your friend here. If you have a part that you want to stand out carve out some space in the other tracks that occupy the same frequencies. Automate your EQ to give space to the main lines when they appear and let that shine. You can achieve the same effect with a dynamic EQ if you have one available. Compression can also help if the offending part is percussive in nature or has a spiky edge so experiment with faster attack times, or even with a transient processor, to tame high energy spikes. Try to avoid EQing parts in solo as it’s all too easy to mix a part to sound great on its own and lose sight of the overall picture. If you want to add more to a part remember that with additive EQing less is more. Use your ears and don’t be afraid to back off if you’re unsure – at the mastering stage it’s much easier to add a touch of “something special” than to remove a problem.
- Mix is muddy or excessively thick. Odd rumbles, lack of definition, bass fighting kick, kick fighting bass, bass and kick fighting a weird energy that’s pumping in time with the pad or lead or high hats… Low end can come from anything, and from many places you don’t expect. If there’s an excess of low frequency energy it can cause all sorts of problems at mixdown and mastering by eating up headroom, interfering with compression, and generally being a PITA. This is a big problem if you’re working with audio that’s been recorded through microphones as they tend to pick up all manner of bumps, knocks and rumbles. Synths and samples also contribute to muddying mixes as their sounds can be very full sounding which, in the context of a mix, can be inappropriate as you may only need a section of their frequency content to get the effect you’re after.
One of the first things you can do is identify which tracks should contain the low frequencies (e.g. kick, bass, that tuba freak-out in the breakdown, etc…) and then put a high pass filter on every other track to completely remove any rogue frequencies that may otherwise be free to roam. This will free up all of the low end space for the parts that actually need it. Then, with the parts that you’ve identified as needing the low end, sculpt individual pockets in the mix for them all to live in. An obvious technique is side-chaining the kick to duck the other parts when needed. This does not need to be an obvious “Eric Prydz” effect but can be as subtle as you like. Don’t be afraid to get really surgical with cutting out low frequencies, as many instruments can be brutally hacked at before sounding odd in the mix. Additionally, and maybe counter-intuitively, setting a high pass filter on these low end parts can also clear up a mix in certain situations. I’m not talking a high value here, but cutting out the super low end can give extra room for the vital low frequencies to operate. As always, experimentation is key as techniques and final settings will always depend on the source material.
- Too much processing on the master channel. For better or for worse it’s become very common to mix with lots of processing on the master channel. Nearly all modern music demands a certain sound that can only be achieved through master channel processing but care must be taken as it can be a double edged sword. Too much eq and you skew the tonal balance of the whole track, too much compression and you squeeze the life out of a track, and too many “audio candy” processors will drag in tonal issues, phase problems and all manner of oddities. Many times I've had to send a mix back and ask for a version without master channel processing as it’s been used in an inappropriate way and ruined most chances of getting a good master.
When approaching a mix resist applying master channel processing until you've achieved a mix that’s tonally balanced across the frequency spectrum, has an appropriate dynamic range and, put simply, sounds good. Once you've got your mix structurally developed then start adding small amounts of processing on the master channel and tweak your individual channels accordingly from there.
Special Note – Limiters
Many people will have different ideas as to whether limiters have any place at all on the master channel when mixing. There’s definitely a spot for them when you’re referencing your mixes against commercial releases or if you need to give a preview of your un-mastered track to anyone but it’s probably a good idea to avoid them during mixdown and there are two reasons for this.
- If you’re using a limiter on the master channel to increase loudness and energy take it off immediately. Mixing is about getting your track to sound good, not loud. Mixing into a limiter used in this way will rob you of a chance to hear how your track actually sounds as you’ll be a getting a wonky image of everything that’s going on – dynamically and tonally. Loudness should come at the mastering stage – if you need more volume when mixing turn up your speakers!
- If you’re using a limiter on the master channel to catch peaks or stray transients that are making your track clip take it off immediately as your individual channels are too loud and they should be adjusted. In this wonderful world of computer based DAWs we don’t need to worry about noise floors or signal to noise ratios in our mixers like they did in the days of analogue desks so there’s no excuse to be mixing your channels at levels where they might be clipping, or clipping the master channel when summed together.
It’s important to stress that none of these tips on their own will propel your tracks on to MTV and they’re definitely not rules that can’t be broken, but being aware of common pitfalls is half the battle already won. Keep experimenting, keep cranking out the tunes and practicing your mixing and, as you may have already guessed, the best thing you can do to make great master is have a great mix. Get mixing!