This is an abridged version of a lengthy article I wrote about stereo width and the mono compatibility of music mixes. Producing a mix that is mono compatible is quite important. You may think in this day and age that it is less important because all sound systems and radio are in stereo right ? ……Wrong.

It is more common than one might think to find mono PA systems, FM radio that sums to mono in weak signal areas, in store ceiling PA/radio, small mono mini speakers plugged into mobile phones and mp3 players, unlicensed underground radio (breaking dance music into the scene), resurgence in interest for vinyl releases,  so making your mix sound good in mono remains very important. You should be making a mix that has both good stereo width and good mono compatibility.

You can simply check your mix in mono by mono’ing your stereo master output in your digital audio workstation. If your sequencer/DAW does not have a mono button you can find plug ins that allow this. (Brainworx bx solo, it’s free).

If you have produced a mix that has a significant stereo width and an expansive stereo image you may find that in mono your mix balance sounds very different. The wider your mix sounds in stereo the less compatible it will be in mono. This is because a wide, diffuse and spacious stereo image will often have a high proportion of out of phase signal between the left and right channels.

One major cause of concern is out of phase bass between left and right channels of the stereo image. In extreme cases this can cause complete cancellation of the bass in the track when summed to mono. Imagine your pumping underground dance music track being “broken” into the scene on an unlicensed station and the bass disappearing, that would be a disaster for the tracks first impression.  

Points to especially be aware of:

Avoid the temptation to over use stereo imagizers or stereo width enhancement tools. They can be useful when used with care and moderation and constant mono compatibility checking. Instead try gentle stereo delay based effects and panning. Also make wise choices of sound sources from the outset. Be aware that many preset synthesizer patches are not always highly mono compatible.

Learn to identify left/right channel phase problems by ear. Excessive stereo width is the main reason for a mix not working when collapsed into mono.

Identifying phase issues.

Ideally you would create some out of phase stereo sources and listen to them and try and learn to recognize the sound character of sounds that are close to or completely out of phase between the speakers. You can take any mono sound align them in your sequencer pan them hard left and right and phase flip one of the channels. This will produce a sound which is wide. So wide it sounds unnatural, as you move your head from side to side you will hear the sound jump around and there is no consistency to the position of the sound in the stereo image. Train your ears to identify this sound character.

You can also use visual tools to identify phase/stereo width problems, such as a phase correlation meter. (more on those in my full length article) However it is always best to be able to identify them aurally and not have to rely on a metering device. Once you can aurally identify these problems you will probably never make a mix that has the problems in the first place as you will hear the issue instantly.

If you found this short version of the article of interest type “resound sound mono” into your favourite search engine and you can read my full length article on the subject.

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By Barry Gardner