Mastering In The Home Studio
Part 2

By David Franz

Last month, in the first part of this two-part series on mastering, we outlined the preliminary stages of mastering your mixes with Pro Tools. To recap, first you should bounce down your final mixes at the highest resolution possible. Then create a new Pro Tools session and import your hi-res final mixes into the new session. Adding EQ, Compression, Peak Limiting, and Dither/Noise Shaping is the next step, and bouncing your mastered audio files is the last step. Last month we covered the first two steps, as well as adding EQ. Now let's tackle the rest.

	The Waves Linear Phase Multiband plug-in provides compression as well as additional EQ and limiting, if desired.

Compressors often have their own "sound." Be mindful of this fact. When mastering, you'll often want your compressors to sound transparent — that is, not affecting the overall sound of the final mix too much.

You can use broadband compression, which compresses any frequency above the compressor's threshold, or you can use frequency-based multiband compression to compress certain frequencies more or less than others. Multiband compressors, such as the Linear Phase Multiband compressor from Waves, are often used to adjust the sound of the extreme ends of the spectrum — the lows and the highs — to get them under control and tighten up the mix.

	The Waves L2 plug-in is a great tool for the last stage in your mastering signal flow.

When using limiters, it's usually a good idea to have your mastered signal peak at around -0.1 dB instead of 0.0 dB. This is because actually having a signal strength of 0.0 dB could cause clipping on some CD players. (Note: We're technically talking about dBfs here.)

The DigiRack Dither plug-in.

Dither and Noise Shaping
At the end of the mastering process, all audio files have to end up as 16-bit/44.1 kHz tracks so they work on audio CDs. Bouncing audio from a higher bit depth to a lower one creates unwanted quantization noise that occurs at low volume levels (e.g., on fade outs). Dither and noise shaping reduce quantization noise. In short, dither reduces the bit depth of an audio file by truncating the digital information (usually from 24 bit to 16 bit) and adds a small amount of noise to an audio signal making quantization noise less obvious. Noise shaping moves the noise added by dither into a part of the frequency spectrum that humans are less sensitive to. Dither and noise shaping (both within the same plug-in) should be the last plug-in inserted on your master fader track. (Note: Waves' L2 plug-in has dither and noise shaping built into it. However, a Dither plug-in comes standard in the DigiRack plug-ins with Pro Tools.)

What Plug-ins Do I Use to Master?
Although there are many options, here are the plug-ins I often use to master in my studio:

• Focusrite EQ on individual tracks (if needed)
• McDSP Analog Channel 1 (to give it some analog-like compression)
• Waves Linear Phase EQ — general EQ curve for all the tracks
• Waves Linear Multiband for compression on individual frequency ranges (if needed)
• Waves L2 Ultramaximizer for "look ahead" peak limiting, dither, and noise shaping

	Mastering session (Mix window)

Download this MP3 to hear a hip hop song that I mixed and mastered. The song starts with the final mix, then switches back and forth between the mastered version and the final mix (this is called "A/B-ing"), and ends with the mastered version. The differences should be obvious. Listen for the increased mix clarity, the extended high end, and the wider stereo image on the mastered version.

A/B-ing
A well-known practice in audio engineering, from recording to mixing to mastering, is called "A/B-ing." A/B-ing means comparing the quality of two or more sounds (literally comparing "A" to "B"). For example, you might A/B the sounds of two different mics on the same vocalist, or the sounds of several different reverb settings on a snare, or several overall EQ curves on your master fader track in your mastering session. As you perform the mastering process, it's a really good idea to get in the habit of A/B-ing your EQ, compression, and limiter settings so that you really know how you're affecting the overall sound. Use the bypass button on the individual plug-ins to check the sound against the uneffected final mix, and flip back and forth between different saved plug-in settings to hear different sonic options. Also, A/B tracks that you've already mastered with tracks that you're currently mastering to get a sense of how they sound together.

Bouncing Your Mastered Tracks
Once you've added your mastering plug-ins or hardware inserts, tweaked each individual song to create a cohesive-sounding final product, put the songs in order, adjusted the timing between the tracks, and added all volume rides for fade outs, you're ready to bounce the final mastered tracks so you can burn them to a CD (or create MP3s). Bounce each song individually. Highlight the track you want to bounce and open the Bounce to Disk window. Select the following settings:

Bounce Source: the main stereo outputs of your system
File Type: WAV, AIFF, or MPEG-1 Layer 3 (MP3)
Format: stereo-interleaved files (for burning to an audio CD)
Resolution: 16 bit
Sample Rate: 44,100 Hz (44.1 kHz)

The Bounce to Disk window with mastering parameters.

A few notes: 1) You'll probably want to choose "convert after bounce," because converting during bouncing can eat up a lot of system resources and could reduce the number of plug-in instantiations available. 2) To change the sample rate conversion quality, go to Preferences and click on the Editing tab. (Check out the Pro Tools Reference Guide for more on this). 3) Pro Tools does not create PQ subcode data — the stuff needed to write specific track information, like running times and index numbers. If you want to customize the track layout of a CD or add complicated crossfades between tracks, you'll need specialized mastering software.

Once you've bounced your mastered tracks, burn them to a CD using a CD burning program and you're good to go. You've mastered your own recordings!

Thanks to Scott Elson (my close friend and protégé of legendary mastering engineer Bob Ludwig at Gateway Mastering) for his contributions to this article. To learn more about Scott, mastering, and Gateway, visit Scott's web site (www.scottelson.com) and Gateway's site (www.gatewaymastering.com).

Like what you see in this column? Check out my book Producing in the Home Studio with Pro Tools (2nd Edition). You can buy it online right here through Digidesign's website, or visit www.protoolsbook.com. Interested in personal instruction on Pro Tools from yours truly? Visit www.berkleemusic.com and learn about several amazing Pro Tools learning experiences available online though Berklee College of Music. Wanna see my studio and hear some samples of my work? Visit www.undergroundsun.com.

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