Clean up the bass area
In fact, the Low End area of the final track often requires cleaning with the mid/side EQ, whether we are dealing with a rock song or trance music. Keep in mind that human ear badly perceives the spatial position of the bass sounds, so if there’s any bass content in the side channel, the overall sound of the track will seem blurred. That’s why one of the first actions performed by many engineers during music mixing and mastering audio services is applying mid/side equalization in order to cut unwanted frequencies in the low end. On top of that, it helps the bass to occupy a distinct central position, so it becomes audible in the dense mix. You can find the recommended values for this task, but I don’t support such an approach, as my decision is always influenced by the specific track I’m working with.
Compression and width
Of course, mixing engineer isn’t exactly a wizard’s lab that can turn a bleak mix into a masterpiece, so the sound width should be achieved initially. However, occasionally this aspect requires some interference. For example, you can make the sound a little wider with the help of a mid/side processing by selecting compression and output level parameters for the mid and side channels. If you densify and lift the side channel level, the stereo component of the song will become more audible and the subjective width of the track will increase a little. For more details please have a listen examples of mixing mastering. To reverse the process (yes, sometimes it’s necessary) you have to focus on compressing the mid channel. However, a studio engineer should be very careful with such processing; otherwise, the main components (such as bass and vocal) can become overcompressed.