Mid/side EQ lets you adjust frequencies in the center of a stereo track separately from the sides, which can be an extremely useful technique for mastering. Read on to learn some of our favorite tips for adding focus, width, and depth to your masters using mid/side EQ and to help you enhance your tracks using mid/side EQ while mastering.

https://www.masteringthemix.com/blogs/learn/how-to-use-mid-side-eq-to-elevate-your-masters