Mid-Side technique is one of the most used tricks that helps correct the stereo sound image of the whole song, or individual elements in it. It introduces wideness and can be found in most compressor units as well within equalizers.
These days, many plugins can take an L/R signal and encode it to a Mid-Side (M/S) signal. As a result, this opens up different possibilities which are really useful, especially in the mastering process. Essentially, the Mid signal is the sum of left and right channels summed to Mono, while the Side signal is the difference between Left and Right channels, or in other words, everything that is different between the left and right channels.
In most cases, the right place for you to put your equalizer, exciter or compressor, that allows Mid-Side (M/S) processing, would be the master buss. The reason for that is because all of your audio signals are summed together into the master buss. It goes without saying that in most cases you will have some instruments like bass, kick drum and snare positioned in the center, and instruments like guitar, synth lead on the sides.
To start with the demonstration and present the changes in the overall stereo image I will apply this technique on the track previously made in Lumit.
The plugin unit that I have chosen for this demonstration is Bx_Control by Brainworx. It is a relatively simple plugin in which I can show you the difference between mid, side and full stereo signals. Lets begin by placing it on the master buss channel rack within Lumit.
You will notice the red arrow pointing to the Stereo width knob. This knob actually controls how much of stereo widening would be applied to the overall signal (balance between the MID and SIDE parts of the signal). When you open the plug in this parameter is set to 100 % and if it remains unchanged it doesn’t affect the signal. But moving it to right you will start to hear the mentioned effect. I am of the opinion that the sweet spot in this case would be around 200 %, because pushing it more could ruin the entire mix by bringing some of the instruments side signal to extreme, and this is something that I certainly don’t want to happen.
To sum up, let us listen how the track sounds with the Bx_control bypassed, Mid signal soloed, Side signal soloed and in Full stereo. Try the Mid-Side technique for yourself, it helps a lot!
~ Bx_control bypassed
~ Mid signal soloed
~ Side signal soloed
~ Full mix