One of the largest problems facing a mix engineer is the unpredictability of the receivers listening platform. In this modern technological age music is consumed constantly but the variety of listening platforms available make it impossible to determine the platform that the track is being mixed for. It must therefore be optimised for all listening platforms. The two most common spacial imaging setups within music are stereo and mono. Stereo referring to the use of two speakers to create a stereo image and mono referring to a single speaker with spacial, directional abilities. Common stereo platforms are headphones, car speakers, or computer speakers. Common methods of listening in mono are laptop speakers, wireless bluetooth speakers, Amazon Alexa’s and phones. With us being unable to predict where our mixes will be listened to it is of the upmost importance to check that mixes work in both mono and stereo.
To achieve this we should aim for a mix that contains the same information whether in mono or stereo but stereo simply providing a wider stereo image. To do this we firstly remove the concept of stereo imaging and focus on the dynamic and frequency relationships between the sounds, EQing and mixing our tracks so that all of the instruments are clear and cohesive. This process must take place because our brains are very good at differentiating sounds if they are placed within a space. Meaning that we are much more capable of isolating a sound source mentally if we receive it in different ears. This is often referred to as the cocktail party effect. If we have many sound sources being received by the same ear at the same time we are incapable of decoding the sounds. Effectively meaning that introduces the stereo image too early in the mixing process can lead to not noticing crucial problems because we are able to decode the sounds because our ears are receiving them respective of our positioning. So by adding mono flip we are able to work on the sonic and dynamic qualities of the sounds against one another truly.
Many plugins offer the capabilities of mono flipping, my particular go to plgins are the Scheps 73 because I like the sound that it makes anyway and it is capable of a high level of transparency so its suitable for use on a master bus and the Waves SSLChannel for similar reasons. If using a software plugin for mono/stereo flipping it is a good idea to setup a keyboard shortcut for quick checks, making the process more intuitive.