Learning Audio Mastering Through Presets

Part 2: Mid/Side Processing

Tips & Tutorials  |  June 5, 2014

This is the second in a three part series of blog posts taking a look at some specific mastering techniques as demonstrated by some Ozone presets, and dissecting the settings being used.

Be sure to also read Part 1: Multiband Compression and Part 3: Using an Equalizer.

This blog has been edited from its original format; some references have been changed to reflect Ozone 7.

Mid/Side Processing

This is a mellow rock song. When mastering in the rock genre, one of the goals is to make the song sound up front, and wider, but without seeming over-processed.

The challenge is twofold. Acoustic instruments such as voice, piano and drums can sound unnatural if too much processing is applied. Simply widening a track using stereo imaging tools may not always work, as this might make the instruments panned to the center sound less powerful as they get stretched across the stereo image.

In order to enhance the perceived width of this mix, and make it sound polished, the “Mid-Side Master - Add Richness and Depth” preset has been loaded in Ozone.

This preset works because it uses a technique called Mid/Side processing. Mid/Side processing divides the signal into a center channel and a side channel, allowing different settings to be applied to the audio in the middle of the mix vs. the audio that sounds like it’s coming from the sides of the mix. Thus, it is possible to make the mix sound wider while simultaneously preserving the presence of the important elements (vocals, bass, drums) panned to center.

Listen to the audio example below with no processing, then compare it against the “Mid-Side Master - Add Richness and Depth” preset.

What can be learned about Mid/Side processing from this preset?

To increase the punch and presence, there is an EQ boost in the low end (around 200Hz), and a cut in the mid range (around 800Hz). This EQ curve affects only the Mid channel, where the drums and bass are typically located, meaning that these EQ changes will likely only affect those instruments, preserving the sound of the wider ambience.

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To enhance the perceived width and add a ‘sparkling’ quality, there is a high shelf filter affecting only the Side channel. This filter adds a gentle boost centered around 6kHz and above, which means that the reverb, ambience and wider parts of the stereo image will sound brighter, without adding harshness to the Mid channel, where the vocal sits.

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The compression on the Side channel is less extreme / non existent, because the more sustained, reverberant, ambient sounds typically found in the Side channel are more susceptible to sound obviously squashed. For this mix, treating the Side channel more gently helps achieve a more transparent reduction in dynamic range.

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Mid/Side can be a very seductive sound but does not always translate to a better result for a mix. It's important to always be aware of the effect settings are having on the mix by listening closely. Very gentle Mid-Side processing is generally favorable, making it possible to avoid extreme settings that can cause phase shifts or imbalance issues.

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