How to Master a Song in Audacity
By Scott Shpak
Updated September 22, 2017
Mastering a song is one of the last steps prior to releasing a song for the world to hear. While in the professional world mastering is done by engineers with particular experience and equipment to do the job, with care and patience a home recording enthusiast can perform some of the functions of mastering. While it is unlikely that it will equal the results from a professional mastering facility, the hobbyist can gain some insight into the process by using Audacity -- a free cross-platform audio editor -- as a mastering tool.
Work with a stereo mix of your multi-track project. Mastering is done to balance and optimize a finished performance and the better your mix is, the easier it will be to master.
Open your mix in Audacity by selecting "File" from the menu bar. Click on "Import" from the drop-down menu and load your mix file. Audacity will assign it to a track. Repeat the process and open a second copy of the same file. When it is assigned to a track, click the "Mute" button on the left. You will use this copy for A-B comparison with your mastered file.
Use Audacity's built-in effects to process the un-muted track. First, select "Equalization" from the "Effects" menu bar. Consider small EQ changes to problem frequencies. Areas to watch are extreme low bass, below 80 hertz, where too much content can make things muddy and indistinct. Frequencies around 400 to 600 hertz can often be lowered a little bit to balance highs and lows, and sibilant frequencies can be addressed with cuts anywhere between about 3,500 to 10,000 hertz, depending on the voices.
Select "GVerb" from the effects menu if you wish to put a little reverb on the entire mix. This is sometimes handy for blending voices and instruments together. Generally you will want only a touch of reverb. Start with a small room size and reverb time and a dry signal level about -4.0. Play with the parameters until it is difficult to tell if there is any effect on at all, then compare it with the muted copy. You will likely be surprised how much reverb is on your mastered version. Beware of adding too much.
Open "Compressor" from the "Effects" menu. Compressors and limiters smooth out dynamic changes, making tracks sound more "punchy." This is an effect that can also be overused, so start with modest settings like a ratio of 2:1 or 3:1 and short attack and release times. Uncheck the "Make-up Gain" box unless you are mastering a high-energy, loud song.
Many of the other effects included with Audacity may be used at the mastering stage with discretion or for a special effect. If the finished version of your song depends on an effect at mastering, that's probably a sign that your mix needs work.