Stereo
Stereo is when you have both “left and right audio signals.” This page will cover the differences between and uses of mono and stereo recording, panning, pan laws, mono compatibility, stereo widening and mid-side processing.
Specification 👇
Component 1 Specification
Component 2 Specification
Component 3 Specification
Component 4 Specification
Mono vs. Stereo
Mono is “a single sound source, speaker or channel.” A lot of instruments and sound sources will be record in mono (ie, using just one microphone). For example, it is common to record vocals and bass instruments in mono.
Stereo is when you have both “left and right audio signals.” You will get this if you use two microphones to record a sound source. Both microphones will be recording the same sounds, but their outputs will be slightly different as they are pointing at the sound source from different angles. It’s common to record instruments such as pianos and choirs like this in order to fill the stereo field when it comes to mixing.
Panning Positions
The stereo field is “placing audio in a mix so that they are perceived by the listener as either being central, left or right.“
Panning is slightly different when mixing mono and stereo signals. When panning a mono signal, you are deciding where in the stereo field you want the track to be, whether it’s centre, hard left, hard right or somewhere in between.
When panning a stereo track, due to the fact that there are two channels of audio in that one track, the pan knob acts more as a balance control. Panning the track to the hard* left will allow only the left channel signal through. Panning the track hard* right will let only the right channel signal through. A centre pan will make the channel signals evenly balanced.
There are no real rules when it comes to setting pan positions, but there are some common practices. For instance, it is common to keep the bass, kick drum and vocals panned to the centre. All the other instruments that you have can be panned at various different degrees left and right.
*if you set your panning to either 100% left or right, this is known as ‘hard’ left or right.
Pan Laws
There is an auditory phenomenon that makes it seem as though signals sounds quieter the further away that they are panned from the centre.
Pan laws are in place to compensate for this skewed perception. They can either make it so that the signal is boosted by a certain amount of dBs when it’s panned to the left or the right, or they can reduce the signal output when it is panned to the centre. This is done so that when the pan position of a sound is changed gradually, there is a smooth transition from one speaker to the other.
This video explains this concept in more detail and shows you how to set pan laws in Logic Pro X.
Mono Compatibility
A stereo mix with a high level of mono compatibility means that the mix sounds the same in mono as it does in stereo. A low level of mono compatibility will mean that the mix doesn’t sound the same, or sounds ‘worse’, when played through a mono playback system when compared to a stereo playback.
Creating a mono output from a stereo mix, or mono summing, is done by feeding both channels of your stereo mix to both of your speakers, rather than just feeding one signal to each speaker.
This works because mono has two completely identical channels; if you panned one left and one right, it would be still be mono. However, if you changed one of the signals on one of the channels slightly, it would become stereo as the signals are then no longer identical.
A project mixed in stereo with poor mono compatibility will not sound the same when played back in mono. Phase cancellation can occur due to slight timing differences between the left and right signals. In a stereo mix, slight timing differences between the left and right channels are what give the impression of a stereo field. When the signals are summed to create a mono output, the signals will be out of phase with one another, causing some frequencies to be cut.
Stereo Widening
Stereo widening, as the name suggests, creates a wider stereo image in your mix. This can be done by applying a stereo widening plugin to a track or your master channel. It can also be achieved by duplicating a track, changing something about the copy (timing wise or with EQ for example), and then panning the original copy hard left and the duplicate to the right, or vice versa.
Mid-side Processing
Mid-side is a stereo microphone configuration technique. Please see this page for more in-depth information on the configuration.
As shown by the diagram below, when processing a recording from a mid-side microphone configuration, each signal must be panned differently to achieve the full stereo effect. The 'mid' microphone ("Mic 1") is panned to the centre. The 'side' microphone signal is duplicated; the original signal panned to the left and the copy panned to the right. This copy must be out of phase with the original signal.
