Mastering Your Song on the Master Bus: Audio Mastering Hack
You’ve taken your mix as far as you can but it still doesn’t match your reference tracks and it feels like you’ll never make it sound radio ready… it’s not your mixing skills, you need to master your track.
Audio mastering was once a dark art. Mastering engineers were the only ones who understood it or knew how to do it. Audio mastering was a complete mystery to everyone else.
Now with a Digital Audio Workstation anyone with enough training, patience and practice can create a decent sounding mix. Once your mix is finished, the next step is audio mastering.
This is one of the last steps in Singer Songwriter’s Ultimate Guide to Home Recording series.
In this article, you’ll learn…
- What audio mastering is,
- What the technical terms used in audio mastering mean, and
- You can watch me demonstrate a modified version of audio mastering on a mix.
I demonstrate a variation of the audio mastering process. “Faux-mastering” is a hack using the mastering process on the master bus of your mix to simulate audio mastering. The full mastering process deserves its own article.
After the video lesson, you can read a written summary of the process, including the plugins and the settings I use as a starting point.
What is Audio Mastering?
Mastering is, in the simplest terms without unnecessary technical jargon, taking a finished mix and maximizing the sound for broadcast.
You raise the final volume level of the song while adding equalization and compression to make it sound great on radio or streaming. It needs to sound good on any sound system from earbuds to a set of professional speakers.
Think of mastering as photoshop for music. There isn’t a stock photograph or magazine cover published that hasn’t been edited with photoshop or a similar program. Any professional song available for streaming or purchase has been mastered. Another analogy is to think of mastering as taking an awesome painting and putting a customized frame on it to make it stand out when you hang it in an art gallery with other paintings.
Reference tracks can help you with recording and mixing. I even use a variation of this concept to analyze and borrow songwriting ideas from songs I love (read all about it in: Songwriting Reference Tracks). I didn’t introduce reference tracks until this lesson because unless you understand that they are mastered tracks and you can’t reasonably match them with an unprocessed recording or with a rough (unmastered mix) without boosting them extremely high (too high to mix with them). Now you know enough not to let reference tracks discourage you!
How This is Different from Professional Mastering…
A disclaimer before we begin: the process is similar to how I’d master an EP or album. This “simulates” mastering on a song with a plugin chain on the master bus. It’s “faux-mastering”, it’s not how a professional mastering engineer works.
Faux-Mastering is different because:
1. Professional mastering is done on several tracks for an album or EP with finished mixes.
2. If you’re mastering audio properly, use speakers set up in a room with audio treatment, not headphones, and
3. Pay more attention to your reference tracks than I do in the demonstration. I’ll explain that more during the demonstration.
I’m cutting corners in this process because throughout this series I’m demonstrating the recording process from setting up your studio to a finished master ready for distribution using the bare minimum of gear and plugins. Then you can follow along and start doing it yourself as quickly as possible.
Who wants to wait to start home recording if you can actually get started now?
Audio Mastering Technical Terms You Need to Understand
For mastering there are a few technical terms you need to understand. There are a few ways to measure the volume of a digital sound file: the Peak Level, RMS, VU and LUFS.
1. Peak Level
The Peak Level is the loudest sound level measured in decibels. This can refer to any sounds that stand out in a part of a song, or to the single loudest moment in a track. 0 decibels or 0dB is the loudest sound you can have in an audio file.
When peaks go above 0dB it’s called clipping and it sounds terrible. When mastering you want loud but not too loud. If your peaks go above 0db you’ve made it too loud. -1dB is used instead of 0dB for mastering because if you change the sample rate or the bit rate when you render a song (turn it into an audio file) it’s possible for some peaks to go slightly higher.
2. RMS Level
RMS, Root Mean Square, is a way to measure how loud sound seems to human ears. Think of it as the average loudness of sound over time, not at an instant the way a peak level is measured. The audio volume meters on your DAW typically measure RMS levels in dB.
Read more about RMS:
VU or Volume Units, measures the audio volume of a signal. Mechanical VU meters were the standard way to measure audio signals since 1940. I’ll demonstrate a VU plugin that can help you set the audio volume while you’re mastering in your DAW. For a more technical explanation and links to get your own VU meter plugin click on this link (not an affiliate link)…
Klanghelm (14 Euros, about $18USD, $22CAN)
Read more About VU
VU Meter Plugin | Waves (not an affiliate link, demo version is available)
LUFS is Loudness Units Full Scale, measures loudness with a different formula than RMS. LUFS was first introduced in 2006 to set a universal standard for streaming. Loudness Units are a more accurate way to measure the perceived volume of sound. It gives more importance to the frequencies that humans hear as louder so it’s considered better than RMS or VU metering to set sound levels.
Streaming and broadcasting uses the LUFS level to normalize audio, automatically setting a similar volume level between different songs. This prevents sudden changes in how loud music sounds between songs, like the shock you get with screaming commercial breaks when you’re watching television.
LUFS for mastering are measured in two ways:
1. LUFS short-term, over a short time frame, think of it as a brief check in. The other measurement is,
2. LUFS integrated which is the level averaged over the entire song. The standard is slightly different between each platform, ranging generally between -10 and -16 LUFS integrated.
In the demonstration I use the free version of the Youlean plugin to measure the LUFS as I master the track. Click this link to get it (not an affiliate link, full version is $29USD):
Read more about LUFS
5. Dynamic Range
The difference between the loudest and softest sounds in your song in the dynamic range. The current standard for most popular music genres is 8 to 12dB of dynamic range on a mastered track. Dynamic range is one dimension to add more interest to your music.
When the dynamic range is very small the music sounded “squashed” or “over compressed.” There’s little change, like someone who’s yelling at you… after a while you have trouble paying attention and it’s hard to understand what they’re saying.
The challenge in mastering is making the music loud (without clipping) while still keeping enough dynamic range to make the music sound interesting. Otherwise you could crank the gain, slam the song through a limiter to make it LOUD and go out partying with the band!
The mastering process I demonstrate in the video simulates mastering, but isn’t exactly how it’s done by professional mastering engineers. Mastering on your Master Bus is “faux-mastering” for a single song… the process is similar but it’s done with several fully rendered songs, not on the mix bus. One goal of mastering is to use similar (or the same settings) on all songs so there is a consistent sound on every track of an album or EP.
Master Bus Plugin Chain
The mastering chain is: Gain, EQ, Multiband Compression, Limiter, VU Meter, Youlean Meter
My Audio Mastering Process is:
1. Insert all plugins in the FX Bin
2. Set the limiter first, so you don’t have to worry about hearing peaks clip above odB when changing other plugins
3. Set the initial volume level with a gain plugin. Changing the gain or faders on tracks or other buses changes the signal levels running through compressor plugins which changes how hard they affect the signal, undoing the time you’ve already spent mixing.
4. Set the EQ plugin to improve the sound of the song. You can also try to to match the EQ curve of your reference track.
Subtractive EQ can reduce some of the louder frequencies so you can push the volume up a little higher. If you feel like you need changes of more than 3dB you should go back and fix the mix.
5. Set a multi-band compressor to increase the perceived volume without increasing the peak levels.
6. Last plugin that affects the signal is a limiter (or a stock compressor set with the ratio as high as possible) to prevent any peaks above -1dB so you can push the level without any clipping. For most genres, aim for 2-5dB of gain reduction on the limiter.
7. Then go through the entire plugin chain again (as many times as you need) to get the best balance between the peak levels and the perceived loudness without squashing out the dynamic range.
Remember good mastering should be transparent, so you don’t really notice it. Make the track sound louder, but not different. Use your best judgement, improving the sound is more important than hitting certain settings on your meter plugins.
Make your tracks sound better and louder, not just louder!
Mastering Plugin Settings
A gain plugin changes the signal level. Use any gain plugin you like. Increase the gain until your peaks are close to -1dB.
Bonus, you can use automation to change settings on a gain plugin. It’s rare to do this while mastering, but it can be useful while mixing.
I usually roll off the low end with a high pass filter set to 60Hz (adjust the frequency to cut out anything lower than the lowest sound in your song).
Optional: turn on one filter band and sweep for unwanted sounds or places to boost frequencies to improve the sound (read my Mixing with EQ article for exact details) )
To use subtractive EQ, watch for the highest peaks on a graphic EQ and turn on a filter band to reduce it a few dB.
Test a slight high end boost (use a shelf filter set to 10kHz and sweep it up and down to adjust. See Mixing with Automation, where I set this up in the Master bus and activated it in every chorus).
Any EQ changes of more than a few dB should be fixed in the mixing phase, not while you’re mastering (I try to keep changes to 3dB or less).
To ensure that mastering sounds transparent, the best practice is to keep the: attack, release, ratio, threshold and gain the same in all bands. Otherwise you can create unnatural or strange sounding changes to the mix. Select all bands then change the settings.
Use 3 Compressor Bands with Cross Overs at 160Hz and 3500Hz
Gain Reduction: adjust all bands at the same time, aim for 2-5dB gain reduction in the compressor band that’s compressing the most.
Gain: add the same amount of gain in all bands to compensate for the compressor with the most gain reduction.
Attack fast 0-10ms (some limiters don’t have adjustable attack, if there are a few setting choices pick: fast)
Release 100-200ms, be sure it releases before the next peak. Test “auto release” if it’s available.
If you’re uncertain of the release time you can use the same process I discuss for setting release time on a compressor in: Mixing with Compression.
Set to VU and calibrate to -10dB. Most of the song should
With the VUMT you also have the option of setting it to “Value” so you see the exact value, and “Hold” to show peak values longer.
Aim for -16dB LUFS integrated to comply with requirements for most streaming platforms.
Other settings vary by genre. Check your reference tracks to find the best settings for your genre, especially for dynamic range and LUFS (short term).
Then use your ears. I felt that my song started to sound worse when I pushed to the same loudness and peak levels as my reference tracks. Those songs were professionally mastered by people with more experience than I have, they could push the music to those levels and make it sound good.
Audio Mastering Summary
Mastering a song makes it sound better. It’s done by increasing the gain to make it louder. EQ sculpts the sound to make it sound better. Multiband compression increases the apparent sound levels without increasing the peak level. Limiting, at the end of the chain, evens out the levels of the peaks without letting any clip and create digital distortion.
Just like songwriting, mastering (and recording and mixing) requires knowledge of best practices and gets better with experience. Balancing the many variables gets easier the more you try. You’ll get better with practice. The first song you wrote wasn’t your best song ever. Take time and enjoy the learning journey!