Saxophonist Blog


Audio Levels in Digital Audio

Although I've spent many hours as a musician in recording studios, my experience on the other side of the glass at a recording desk was usually to listen to recorded audio and comment on editing and mixing. Over the last decade I've become more involved in the actual recording, usually of saxophones or the production of electroacoustic music. I thought it might be useful to list a few basic things that I had to understand in the beginning. Absolutely basic stuff for a properly trained audio or recording engineer, but for instrumentalists perhaps not.


Recording Saxophone (particularly Classical)

You can easily find recommendations for the best microphones to record acoustic instruments. Microphones can colour the recorded sound and be weighted towards particular frequency ranges, similar to speakers really. I chose two diaphragm microphones with a particular recording pattern that produced a neutral sound with little added warmth, and also weighted to focus a little more on high frequencies; they're incredibly sensitive. I'm comfortable that they seem to record a pretty good representation of acoustic sound across the whole family of saxophones.

I use Focusrite audio interfaces and Logic Pro X. I often find that recording to a peak level of around -12 dBFS works for me, you'll have to experiment. The timbre of the recorded sound will change with different microphone positions. I've experienced the 'microphone in your bell' position in various ensembles, which produces a completely different (and unnatural?) sound to a position further away, especially for classical saxophone.

When I've finished recording and I'm working in Logic Pro, I use a combination of the Logic Pro plugins (particularly the Space Designer convolution reverb) and the excellent FabFilter plugins.


Levels within your DAW

  • Use 24 bits rather than 16 bits. This will give you a larger dynamic range and enable recording at lower levels with more headroom (to avoid clipping and distortion).
  • Record with a peak level -18 to -12 dBFS to allow for later mixing and other processing.
  • Use a gain/trim plugin as the first insert on a channel to begin with an adequate audio level, then keep an eye on the levels as the channel travels through any plugins: you can use the output level of any plugin to correct levels.
  • Don't attempt to end up with a mix that peaks at 0 dBFS, that was the old days of 'loudness wars'.
  • Set the target level on loudness meters to match the required streaming/broadcast levels.
  • Don't normalise when bouncing.


Bouncing Your Mix

Before creating a final audio file you need to be aware of a few things. National and International organisations have agreed a set of protocols relating to audio delivered over different technologies such as YouTube, Spotify, iTunes etc. If you don't comply to the rules, they have algorithms in place to alter you audio to ensure you do.

Rather than focusing on peak normalisation, it's better to look at Loudness Normalisation.

  • LUFS Target Level. Different systems (streaming, radio etc.) has different requirements regarding loudness. The European level is -23LUFS, America -24LUFS and streaming services around -16LUFS or -14dBFS.
  • If an audio file exceeds the target level, the audio is raised or lowered until it meets the rules. This means that if you have produced a highly compressed audio file at a high LUFS, it will be lowered to meet the rules, but sound worse because of lack of transients and dynamic range.
  • Keeping the peak of your mix below -2.0 dB on a true peak meter will avoid clipping and distortion during any transcoding processes, or adjustment by a streaming service.
  • Audio with a larger dynamic range will usually sound better than more compressed audio.



Target Levels for Streaming Services

Service Loudness Peak
Apple Music -16 LUFS -1.0 dBTP
Spotify -14 LUFS -1.0 dBTP
Amazon -14 LUFS -2.0 dBTP
YouTube -14 LUFS -1.0 dBTP
CD -9 LUFS -0.1 dBTP
EU Broadcast -23 LUFS
US Broadcast -24 LUFS



Terms used in a DAW / Logic Pro's meters

LU

1 LU equals 1dB

LUFS

Integrated Loudness, the average loudness. Use to check if your level adheres to the streaming or broadcasting rules of the service you're using.

True Peak

True Peak Meters detect inter-sample peaks to give a more accurate reading of peak levels.

Peak to Loudness Ratio

This is the difference between the average loudness (LUFS) and the True Peak level.

LU or LRA

Loudness Range. Shows the dynamics of the audio material. This is not measured from lowest to highest point, rather an average dynamic range. I prefer as wide a range as possible for recording classical music.

Remember you can set your target levels in Logic's level meter plugins by sliding the little yellow (or orange?) line. Then you can more easily get a sense of your audio levels. I aim to get a good dynamic range for acoustic recordings, often avoiding compression as much as possible.


Some great sources about recording:

The Institute of Audio Engineering

Logic Pro Gem

Mastering the Mix

Bartlett, B. and Bartlett, J. (2009) Practical recording techniques: the step-by-step approach to professional audio recording. 5th ed. Burlington, MA: Focal Press.

King, R. (2017) Recording orchestra and other classical music ensembles.

LinkedIn Learning: There are so many great courses giving an insight into basic recording and editing, to mixing and on to mastering. Sometimes the courses are free if you are involved in a university.