How to Prep a Mix for Mastering
Preparing a Mix for Mastering
You’ve finally finished that mix that has caused many sleepless nights. The snare doesn’t sound like sh*t, the bass slaps, and the vocals cut through with the clarity of an angel. It’s now ready to be sent off to mastering, but how should you send it? Should you remove master buss processing? How much headroom should you leave? These are perfectly valid questions, and are best discussed with the mastering engineer of your choice, as many will ask different things. I’ll discuss what I want from a mix and what I request of anyone that hires me.
The mix. At the end of the day I want what you believe is the absolute best mix you can get. If that means you have eq and compression on your master buss, so be it. I like to work with open communication when possible. If a mix engineer is unsure which is better, sending a version with and without master buss processing is a perfectly valid. The one thing I generally ask is no limiting on the master buss unless its for some creative purpose. The reason for this is that limiting is a destructive process and better results will be had with a file that has not had information removed. This brings us to our next point… Headroom. You have all heard this internet myth of leaving anywhere from -3db to -6db of headroom. Here is why this is not only not necessary, but potentially deceiving. Leaving headroom is great, and what most mean by this is “give me a mix that isn’t clipping”. This circles back around to the use of a limiter as well. If you remove the limiter on the master buss, your mix may now clip. The easist solution is to place a gain plugin last and simply turn down the mix until it doesn’t clip anymore. This will preserve the entirety of the transients in the mix without clipping or the use of limiting. The amount of headroom in this instance is completely irrelevant. Whether it’s -3db, or -8db, the important thing is that the mix isn’t clipping. Leaving “headroom” does not mean lowering the ceiling on your limiter to -3.0db.
Samples, Format and Bit. The next step is to figure out what bit depth, format and sample rate should you export at and I always ask for the original sample rate of the project and a minimum of 24 bit depth minimum (32 or 64 bit preferable). I want the original sample rate so I can be in control of the down sampling and choose the type of SRC (sample rate conversion) filters to employ for optimum sonic results. Most DAWs these days are operating at 32 bit sample rates minimum, and receiving a mix at the original bit depth means dithering does not have to be applied. Having a mix that was already dithered is not the end of the world (far from it), but having to dither as few times as possible would be preferable as every step of dithering adds a very small amount of noise to the mix.
The preferred format to deliver a mix for mastering would be a lossless file such as WAV, FLAC, or AIFF. Most engineer will probably just ask for a WAV file to make this less confusing and aside from storage size, there are not really any benefits to using one over the other. Lossy formats, such as MP3, have dumped file information such as high end content in order to compress and make the file smaller, make it unsuitable for mastering (save for extreme cases where a lossless file doesn't exist). It should be noted changing a file more a lossy MP3, to a lossless WAV, does not restore the lost information even though the file has changed. This is especially important for individuals using instrumental tracks they may have purchased and a good reason to always get the best quality file(s) you can. As you can now see, it’s not a difficult feat prepping a mix for mastering. If a particular engineer is asking for magical numbers to deliver a mix to in terms of headroom this should be a cautionary flag to you as all of us have gain and trim plugins in our DAWs of choice and can tweak this to our own specifications. At the end of the day, supplying an unclipped file without a limiter, in its original sample and bit rate is really all there should be.