Recording and processing audio can be a complicated process. If you're unfamiliar with the Mid/Side technique, this article is for you!
Don’t worry! Today, I’m going to make it really easy for you and break down everything that revolves around this interesting method of working.
What is Mid/Side?
To break it down simply, Mid is the center of the stereo image. When the mid signal is boosted, the listener can observe a centered sound to the audio. It’s going to give the impression that the signal is more mono than stereo.
Side, is the edges of the stereo image. So when you boost the side signal, it will give a more spacious sound to the audio.
Conceptually, mid/side originated from a mic technique created by EMI engineer Alan Blumlein in the 1930s. The objective of his work was to create a signal that closely represented how the human hears work.
It’s been used ever since, often in broadcast, as it’s always mono-compatible if done correctly.
One of the most annoying things about stereo recordings is that they can sometimes have small amounts of phase cancellation when collapsed to mono. On the other hand, mid-side can give you much more control over the stereo width of a signal than any other recording technique.
How is Audio Recorded with the Mid/Side Technique?
With mid/side recording, often 2 completely different microphones are used, with different polarity patterns. For example, the mid signal would be generated using a cardio polarity microphone pattern, and the side signals would be generated using a figure 8 polarity pattern. You need this to create the different parts of the signal correctly.
You’d set up the microphones as follows: One would be directly facing the source, and one would be on top, but with the front and back of the capsule facing the sides. It’s important to place them as close to one another as possible.
Then, the signal of each microphone is recorded into separate tracks. For this to work properly, you’re going to have to do a little bit of a process.
First, take your mid recording and pan it to the center. Then, take your Figure 8 Side microphone recording and duplicate it into two channels: Pan one side track hard left, and the other hard right. Finally, flip the phase on the right channel side microphone track. Decoding complete.
Now, you've got three channels of audio: the Mid center channel and two Side channels, and you can balance them to create the desired effect and space. By bringing up the side signals, you can add more space to the mix.
How to Process Audio with Mid/Side in a mixing and mastering context?
Processing audio in a mid/side mixing and mastering context is quite a delicate thing. It’s easy to mess it up, but it’s quite rewarding if you get it right.
Utilizing an EQ and activating the mid/side mode, you get to independently affect the mid and side channels separately with processing. Sometimes, when mastering, you want to activate a mid/side EQ, reduce some of the sub frequencies on the side channel, and raise the high shelf very slightly on the side channel. This allows the bass to be more centered and creates a bigger stereo spread in the high frequencies.
You can do many useful things, such as fixing a vocal in the mid-channel that's sticking out too much in a mastering scenario using mid/side. Still, you need to be careful because it’s very easy to upset the balance of the mix.
Another way you can apply mid-side processing is to apply mid-side compression. Something like POWAIR from Sound Radix is an amazing compression plugin that I recently just bought personally. It’s one of the most advanced compressors out there and also allows you to compress the mid/side signals independently. Mid/Side compression allows you a big amount of control over the signal and helps you balance things effectively if needed in different scenarios, such as a mastering context.
You’ll actually be able to compress in Mid/Side with Mix: Analog as well!
Mid/Side recording and processing is an exceptionally powerful tool in your arsenal for professional sounding recordings that collapse to mono well and fix complex issues in a mix with ease. Once you wrap your head around the concept, you’ll be making fine adjustments quicker and achieving a much more specific result in your mixes.