Future Music's guide to mastering: Understanding dynamic range and compression
Check out the video above to hear Conor Dalton, a mastering engineer who runs Glowcast Audio Mastering, explain dynamic range and compression.
What is mastering?
"In my experience there seems to be a lot of confusion surrounding the world of mastering, its capabilities and its limitations. I'd describe it as the last link in the music production chain, somewhere between a final mix and a completed project, where audio can be optimised through subtle processing, errors checked and all involved made to feel good. It's the process of creatively enhancing audio before preparing and transferring recorded audio to a device such as a CD or vinyl – and not a chance to remix or fix an otherwise bad recording."
"This master is the copy from which all further copies are created."
What does mastering include?
"Mastering is the final chance you get to sonically change your music through techniques such as EQ and compression and the last chance you get to bring out the best of your sound. As a mastering engineer it's my job to make all the individual elements of the song gel together in harmony, as well as balancing the song tonally with EQ and removing minor flaws such as pops and clicks.
"As I've already implied, if your mix has problems, you're going to struggle to get an amazing sounding mastered record. Mastering isn't the place for fixes, rather it's the art of balance: audio feng shui, if you will. That means that it can never make a bad mix good, but it can certainly help make a good mix great. When mastering for CD, tracks are also spaced with appropriate distance between them so the whole album flows well artistically and ISRC and UPC/EAN codes can be embedded if necessary. Then the 'master' is created, for example a digital WAV or AIFF file, CD or vinyl.
"This master is the copy from which all further copies are created. The goal of mastering is for the finished songs to sound great on any sound system, whether that's a stadium live rig, or a home stereo. You want mastering to be mainly constructive instead of corrective: you want to be enhancing the audio, and not spending all your time fixing mistakes that occurred during the mix. Therefore, it's essential to get your mix sounding just the way you like it to the best of your ability before mastering.
"Your job when applying creative processing techniques in the mastering stage is to recognise the point at which you have successfully pushed the audio to its optimum position, before the sound begins to deteriorate through over-processing. It can also include adjusting stereo width, surgical EQ to remove unwanted resonances, and limiting, for example."
"Understanding your options and limitations is the essence of mastering."
Can you make my track loud at the mastering stage?
"Yes, but something you must understand is that loudness comes at the expense of dynamic range. Mastering is not just simply making something loud. I get asked a lot if I can make someone's song 'as loud as' another artist and one of the most common problems I encounter from tracks I get sent as a mastering engineer is over compression on the mix to achieve loudness.
"Loudness is really an illusion, as we all have volume control on our hi-fi or stereo: I chat some more about this on the video tutorials with this month's magazine. While it's often desirable to aim for competitive loudness, it's not wise to completely kill the dynamic range of your song in order to achieve it. When you reduce the distance between the loudest peak and the quietest sound through compression to achieve loudness you can achieve a 'fuller' sound.
"However, if you tread too far and over-do it, then you're sacrificing some of the essential and powerful peaks for the benefit of the quieter sounds, and as a result you compromise some sonic integrity to achieve that loudness. Understanding your options and limitations is the essence of mastering."
Metering can play a vital part in keeping dynamic range in check
Understanding dynamic range
"Understanding dynamic range is essential to achieving a good sound. It's the difference and distance between the loudest peak in the track, and the quietest sound. Compression reduces this distance to achieve an overall feeling of increased 'loudness'. Now consider this analogy: imagine the dynamic range of the human voice in everyday conversation.
"Remember that the human ear naturally prefers some dynamic range in music."
"The loudest sound in a conversation is a scream, and the quietest sound is a whisper. If you were to reduce the distance in volume between a shout and a whisper, your whole conversation may become more up front and in your face, more exciting, and the whisper easier to hear at the expense of subtly toning down the screaming just a touch.
"However, consider the implications of pushing it too far. The screaming is toned down, meaning less impact and severity and the whispers become inappropriately loud, meaning no more secrets: your conversation becomes less expressive, emotive and articulate if you reduce the dynamic range too much to achieve an overall loudness.
"When using compression, remember that a volume boost or cut added by the compressor is deceiving."
"It's exactly the same for music. Your job at the mastering stage is to recognise what compression (if any) is needed, and how much is appropriate before the audio begins to deteriorate and the sonic integrity is compromised to achieve loudness. Remember that the human ear naturally prefers some dynamic range in music, and an overly loud and compressed sound is very fatiguing to listen to after a while as it lacks depth. Imagine a roller coaster that didn't go up and down, but rather just coasted along on a straight line high up in the air, it wouldn't be very exciting would it? It's the ups and downs in music (and roller coasters) that excite us, so if everything is pushed to become loud then the importantelements of the song that should be prioritised will lose impact."
Tip: "When using compression, remember that a volume boost or cut added by the compressor is deceiving. It's good practice to always volume-match your output with make-up gain, so make sure the compressed and uncompressed signals are the same volume when you flick on/off on your compressor. This way, you only hear the effects of compression and not the unhelpful change in volume, which can trick you into thinking that because the compressed signal is louder it's 'better'. This is a good way to maintain sonic integrity when adjusting dynamic range through compression."
Can I master my own music?
"Of course you can, however, one of the major benefits of having your music mastered professionally by someone else is for a fresh set of ears to provide a new perspective on your music. We all know that feeling when you've been listening to your track for weeks and you just can't tell if creative processing changes are required anymore. This is where a fresh perspective can be essential: A first impression often can reveal a lot about your audio."