Chapter 16

In-the-Box Considerations

An all-digital in-the-box (ITB) mastering setup, whereby all processing is done with plug-ins, represents a worthwhile approach to explore. With an ITB system, you can work with one DAW that can function as both the PBDAW and the RDAW. Naturally, ITB mastering requires a digital source file. Benefits of ITB are: cost-effectiveness, easy recall, and a minimized mastering footprint on the source audio—as neither a DA converter (other than for DAW monitoring) an AD converter, nor expensive outboard equipment, are necessary.


Among drawbacks are that the result may lack some depth, dimension, frequency extension, and vitality. My experiments comparing the same source file mastered through a hybrid digital/analog system and an in-the-box version almost unanimously favor the hybrid result. I do ITB mastering a low percentage of the time, but it remains an effective option for certain projects or revision requests. ITB mastering allows the Mastering Engineer to achieve the desired target level, EQ adjustments, dynamics management, and image/width enhancement, with a result that is well correlated to the flat mix.

When to Use ITB Mastering

Always disclose to your client a decision to approach the mastering this way, as many artists, engineers, and producers specifically seek an analog mastering chain, while others are less concerned. Situations that favor ITB mastering are a client mix on the hot side (+10dBu–+11dBu on your VU meter—likely with some peak-limiting by the mix engineer), a mix that the client loves as-is (they may have grown accustomed to the overall sound), and a mastering revision request with numerous details or concerns about the first hybrid mastering pass. These situations reveal that the mastering process possibly altered the listening experience excessively for the client’s taste. This may occur because the conversion to analog and back to digital, along with the coloration from the analog chain, may alter the qualities and characteristics of the mix enough to disorient the client. If they ask for a revision, listen well to their feedback and decide upon either subtle shifts/adjustments to your original approach or an altogether alternate approach, such as ITB mastering. Experience and judgment enters into how you interpret their comments and select a plan for the revision.

Basic and Advanced Setups

As with an analog mastering chain, one’s initial attempts at ITB mastering are best served using fundamental mastering tools (a compressor, equalizer, and brickwall limiter). I prefer to set up my PBDAW (ProTools) with a separate left and right channel (to verify left and right channel integrity through the mastering system). As a result, I open the plug-ins on the stereo master fader buss. Be aware that nearly all of the advanced mastering methods outlined in Chapter 14 are available virtually ITB. Parallel EQ is especially powerful and effective (see Figure 14.4 for an advanced ITB setup). This is due to detailed parameter adjustments available in EQ plug-ins to create frequency bands of EQ to blend in with the source audio, and one-tenth-of-a-dB fader level adjustments for the parallel blend faders. Always remember to have delay compensation engaged in ProTools with parallel processing, or you will have phase issues and smearing of the image due to delay between main and parallel audio signals.

Digital Hardware Options

A similar approach to ITB mastering, but involving greater procurement cost, would be an outboard chain with all-digital hardware, such as devices from Weiss or t.c. electronic (see Figures 4.12 and 4.35). These are powerful multi-faceted digital signal processing (DSP) devices. Some mastering studios are set up with only a dedicated all-digital hardware chain, but they seem rare. I generally find that clients who may seek these high-end digital devices are also interested in high-end analog equipment for their projects.

Sampling Theorem and ITB

With ITB mastering, the DAW operates at a single sampling frequency and bit depth, usually determined by the source file resolution. If the source file is delivered at 44.1kHz or 48kHz, you can up-sample via sample rate conversion to a higher resolution (88.2kHz—24bit, 96kHz—24bit or higher) so that all the plug-in DSP is completed at the higher sampling frequency and bandwidth. Note that the bandwidth represented by the Nyquist frequency of the lower resolution source file will not change or increase. The advantage of up-sampling is that the DSP occurs at a higher sampling frequency, allowing for the capture of the mastered file at high-resolution specifications, even if the Nyquist frequency limits bandwidth.

Also note there is no way to effectively increase the bit rate of a 16bit file to 24bit in the digital domain; it must be sampled at that resolution at the original point of AD conversion and capture. There are conflicting theories about SRC, and concerns about the process altering a source mix (potentially adding anomalies), so some Mastering Engineers avoid it. Others see no harm and avail themselves of sophisticated SRC software such as Weiss Saracon.

Another clear advantage of an ITB system is that recalls or revision adjustments are lighting fast, as the plug-in chain can be easily saved in the DAW session. A final key point to consider is that for those compelled to develop mastering skills—ideally with access to a network of music creators to draw clients from—an effective ITB mastering can be quicker to setup and implement without the substantial costs of traditional analog mastering equipment.

Figure 16.1

Figure 16.1A basic but very effective ITB mastering chain consisting of the: UAD Fairchild 670, DMG Equilibrium, and UAD Precision Limiter. This makes use of the Primary Colors of Mastering introduced in Chapter 1.

Source: (courtesy Universal Audio and DMG)


As elucidated previously, even if a Mastering Engineer routinely uses a hybrid analog/digital system, there is a place for ITB mastering in their arsenal of approaches. I’ve identified the benefits and drawbacks so that the option may be duly considered. ITB represents a starting point for developing audio mastering skills, and/or an approach for when ‘plan A’ does not resonate with the client. Excellent plug-ins for ITB mastering are bundles or mastering-centric offerings from UAD, Waves, T-Racks, DMG, and Voxengo.


  1. Set up a basic ITB mastering session using The Primary Colors of Mastering (EQ, compressor, and BWL). Take care to avoid over-levels by fine-tuning gain structure through the plug-in chain. Capture the result, and describe the effect and quality of the enhancements.
  2. Set up an advanced ITB mastering session with one instance of parallel EQ or compression. Capture the result, and describe the effect and quality of the enhancements.
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