What Makes a Great Reference?
References are professionally produced tracks used to compare and contrast your mix to those of similar genre and style, to achieve a desired sound, as well as compare frequency information.
You want to be able to accurately compare your work to what's out in the world; your favourite recordings, the things that you admire, or the things which define the genre which within you're working. To do this, you need to be able to hear as closely as possible the audio in the same fashion and form as it came off the mastering desk, unchanged by a distribution service, compression, or medium.
Distribution services will modify the audio to provide a better experience for the listener. But, in doing so, sometimes they will change essential components of the sound that make it hard to compare our work against the mastered version.
Figure out if what you're listening to has been loudness normalised.
Loudness Normalisation: Changes volume to bring the average amplitude of a track to a target level.
If you're using a loudness normalised track as a reference for your mastering work, you're not using the true master, but a version altered by the streaming/distribution service.
When you listen to lossy audio, there are artefacts that you will hear that change the overall tone of the music. You could end up using, as a target, something that's skewed, then when your work goes out, that tone gets skewed once again, and you doubled up that tonal shift.
You can quickly identify with Ozone's codec preview when working with a low-quality MP3 as there is no information above 15KHz. As you increase the MP3's quality, the more high-frequency information becomes present.
When you listen to music through lossy codecs, you'll end up with noise that's a result of the filtering required to reduce the file size.
How to Find Good References For Mastering
Old C.D.s (44100 kHz & 16-Bit)
High-quality streaming services (Tidal, Amazon HD, Qobuz - up to 192 kHz & 24-Bit)
Purchase on Bandcamp or Beatport (Varies, but 48000 kHz & 24-Bit is most common)
MV: Qobuz is the best high-quality streaming service, with Tidal being second. You can purchase music on Qobuz, but the library is limited. I mainly purchase reference tracks from Bandcamp as 24-Bit is what I'm after. You're working at music in your D.A.W. In 32-Bit floating-point, which contains double the bits than a 16-Bit file. 24-Bit is slightly closer, but I would love to see more 32-Bit WAV's available in the future.
How To Use Mastering References
Find a collection of material to distil some general guidance or ideas from.
Match EQ is an option for using a frequency spectrum profile from a reference track. Just feed the spectrum 30 seconds of a track to capture an accurate representation of the frequency curvature. Smooth the curve to get a change in the EQ that's flattering to the track you're working on. The point isn't to copy another track's spectrum, as every track is different.
How To Think About Level and Tone with a Mastering Reference
Turn the reference tracks down a few dB, so you don't turn the level of your track up all at once before you make adjustments. It would be best if you had headroom to work with. Limit at the end of the chain. In the beginning, don't match the level of your track to the reference track; this comes at the end.
The tonal balance control will show you the average spectrum across thousands of recordings, in multiple genres, which you can use to measure your audio against. It's a great way of helping you to gauge if your music is in the ballpark for what is considered a normal distribution of frequencies.
What To Do First With a Mastering Reference
Before Jonathan starts a master, he'll listen to reference material to recalibrate his hearing.
Firstly, he'll listen for tonal or balance issues. He's building a mental model of the given track to think about what may need changing at the global level. Is there a broad change that you can make to move the track in the direction you'd like to go in? Use references to guide you through this process.
It's important to compare your project to the references at the beginning of the mastering stage, as this will inform any significant changes you may need to make.
The idea is to make the track you're mastering the best it can be. So don't get too into the weeds of copying every detail from a reference. Slowly wind in how much the reference influences your decision-making the further you get into mastering a track.
Hallmark of a great reference: Everything should be available to the listener, nothing in a great mix should be hard to find, or obscured by something else. The quality of the recording needs to be high. Music that you like, where you appreciate the craft, beautiful arrangement manifested in a beautiful mix, with a beautiful master.