{"id":6121,"date":"2020-08-18T11:21:39","date_gmt":"2020-08-18T10:21:39","guid":{"rendered":"https:\/\/www.sonarworks.com\/soundid-reference\/blog\/?p=6121"},"modified":"2020-08-18T11:21:40","modified_gmt":"2020-08-18T10:21:40","slug":"pro-mastering-tips-compression-pt-iii-mid-side-compression","status":"publish","type":"post","link":"https:\/\/www.sonarworks.com\/blog\/learn\/pro-mastering-tips-compression-pt-iii-mid-side-compression","title":{"rendered":"Pro Mastering Tips: Compression Pt. III, Mid-Side Compression"},"content":{"rendered":"\n

In parts I and II of this series on compression, we covered traditional stereo compression and multiband compression for mastering or master bus applications. As a reminder, we are going for transparent control to \u201cglue\u201d a mix together, to make the mix cohesive and punchy and bring up some interesting details and depth. This article will present another option for stereo mix compression that offers unique possibilities and may just scratch-an-itch for certain people. As with everything in audio production, opening your mind to a new process will push you to experiment and develop new methods. <\/p>\n\n\n\n

Middle vs. Side<\/h3>\n\n\n\n

To be brief, the mid<\/strong> of an audio stream consists of all the elements that are the same in both the left and right channels\u2014center panned information, and to some extent things that are not panned completely to one side or the other. The side<\/strong> information contains elements that are unique to only the right or left channel. Many digital processors, and some analog processors, can decode these two streams out of a stereo mix, allow independent processing of the mid and side streams and then recombine those two streams back into a stereo mix again. It works, and it\u2019s not magic.<\/p>\n\n\n\n

\"\"
The Waves PuigChild 670 recreates the Fairchild 670, a classic bus compressor that provides stereo-linked, independent, or mid-side (Lat\/Vert) compression options (see the yellow box above). If you thought mid-side processing is something new, consider that the 670 was released in the 1950s!<\/figcaption><\/figure><\/div>\n\n\n\n

Stereo Considerations<\/h3>\n\n\n\n

Before jumping into the details of mid-side compression, let\u2019s spend a moment on stereo linked compression vs. non-linked compression. When compressing a master with a traditional stereo compressor, we typically use moderate compression, which won\u2019t do a whole lot to change the stereo image of our mix. With more aggressive time constants and harder compression, an unlinked compressor may produce different dynamic changes in each channel which may cause the stereo image to wander a bit or become unstable. Linking the compressors left and right sidechains maintains a stable stereo image, but unlinking the left and right channels, even with gentle compression, often produces a subtle increase in stereo width. I\u2019ll let you decide if that\u2019s good or bad.<\/p>\n\n\n\n

In the case of mid-side compression, we are compressing the mono information with one channel of a compressor and both<\/em> the left and right sides with the other channel of the compressor. This method retains the stability of left-right stereo imaging. However, since we are ultimately adjusting the dynamics of the center of the mix against the dynamics of the sides of the mix, we have an opportunity to change the overall stereo perspective from less wide (louder mid<\/em> channel) to wider stereo (louder sides<\/em> channel). I would generally recommend starting with similar attack, release, and ratio settings both the mid and side channels\u2014the amount of gain reduction and the makeup gain for each path are the important considerations.
<\/p>\n\n\n\n

\"\"
UAD\u2019s Elysia Alpha compressor provides a mid-side on\/off switch. In M\/S mode, the left compressor channel affects the mid<\/em><\/strong> and the right compressor channel affects the sides<\/em><\/strong>.<\/figcaption><\/figure><\/div>\n\n\n\n

Reasons for Using Mid-Side Compression<\/h3>\n\n\n\n

The main groove elements and lead vocal typically live in the mid channel, while pads, ambiences, effects, and supporting instruments live in the sides. Mid-side compression, therefore, gives us a chance to control the dynamics of the groove and\/or vocal without affecting the clarity and dynamics of the stereo elements and vice-versa. <\/p>\n\n\n\n

By manipulating the mid channel, we have the ability to enhance the dynamics of the groove, the punch of the kick, or the presence of the snare or lead vocal. Conversely, we can increase the clarity of the details on the sides, which may add rhythm, ambience, and depth to a mix. As a bonus, mid-side compressors provide gain for each channel, so even without any compression, we have level control of the center vs. the sides\u2014an effective stereo-width tool in its own right.<\/p>\n\n\n\n

Many people get by fine without using mid-side compression, or multiband compression, but you should do yourself a favor and try mid-side on a few projects to see where this tool fits into your arsenal. Unlike multiband compression, you\u2019re less likely to destroy a good mix with mid-side compression, just be sensitive to the size of the mix and you\u2019ll be fine.<\/p>\n\n\n\n

In Practice<\/h3>\n\n\n\n

Let\u2019s take a look at some typical problems encountered during mastering and how mid-side compression can solve the problems:<\/p>\n\n\n\n