Audio mastering is the process of taking one or more final mixes, and turning them into a truly finished sounding product. If you were merely to transfer your song(s) directly onto a CD without going through the audio mastering process, and then directly compare it to your CDs at home, you would most likely be shocked at how "unfinished" it really sounds.

Mastering is also the process in which all of your final mixes are assembled onto a Master PMCD (a "Red Book Standard" disc), which CD manufacturers will accept for mass duplication.

Mastering is serious business. A properly mastered CD means you have gotten the absolute maximum potential out of your recording project, and hopefully it will now compare favorably with the best sounding CDs in your collection (as well as other people's collections!). Anything less than that means you have wasted a lot of money. And I don't mean just in the mastering process, but the ENTIRE recording process that led up to it.


audio mastering tip 1
Make very small changes when EQing, because an increase or decrease in one frequency range has repercussions elsewhere. For example, if you boost the treble, the bass becomes less prominent. It's amazing how even a 0.5dB change can make a noticeable difference. Adjust EQ to what sounds right, then halve the amount of boost or cut you added. This gives your ear a chance to get acclimated to the change in sound. You can decide later whether you want something more drastic.

audio mastering tip 2
Always save and back up your original unmastered, 2-track or surround mix before you start mastering, and work on a copy.

audio mastering tip 3
Duplicators will often reject CDs if the level hits 0 for several samples in a row. Yet these very short overloads may not be objectionable to the listener. To get around this problem, after assembling the entire CD, normalize it to -0.1 dB. This leaves just enough headroom that the CD won't be rejected for "overs."

audio mastering tip 4
If you mix to DAT or transfer tunes to DAT prior to sending them to a duplicating house, record a minute or two of "digital black" (silence) at the tape's beginning. This gets past the part of the tape that is most likely to have questionable surface characteristics. You can then transfer the DAT digitally to your computer for editing. Also, eject any digital tape in a space between songs. Should any tape damage occur while threading or unthreading, your song will be spared.

audio mastering tip 5
Think high resolution audio at all times. Save your final mastered versions in at least 24-bit resolution, even if the target playback medium is a standard 16-bit CD. Then apply dithering to the high resolution file to create the best-sounding 16-bit file.

audio mastering tip 6
Use normalization sparingly. Normalization sounds like a great idea: click a button to amplify your signal so that the peaks just reach the maximum available dynamic range. But music doesn't work like that. A heavily compressed tune may seem much louder than a less compressed tune whose peaks are actually higher.

audio mastering tip 7
If possible, test the album's song order before you start mastering. Use your CD burning program or Apple iTunes-type program to assemble a "playlist" of tunes, and record it to Red Book CD, portable MP3 player, Minidisc, etc. Live with the order for a few days so you're sure everything flows smoothly.

audio mastering tip 8
When mastering with a digital audio editor, save the setup you use (plug-ins, levels, etc.) as a preset. For example, Wavelab has a Master Section Presets option. If the vibe of the CD changes over the course of mastering, you can go back to earlier tunes, recall the preset, and make a few tweaks rather than start over from scratch.

audio mastering tip 9
Don't do any more processing than needed. These operations sometimes round off numbers; if these errors accumulate, there can be an audible "fuzziness." While this was mostly a problem with 16-bit systems -- 32-bit floating resolution has given a lot more operational headroom -- it's still a good idea to keep any processing to a minimum.
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