Despite that Stereo systems were invented over half a century ago and multiple channel speaker configurations are the standard in cinemas and home theaters systems for the last twenty years or so, mixing in Mono, or at least checking a mix in Mono is still crucial. And yes, not only for mono playback systems but also, it can help you set your elements in the stereo field.
Stereo vs L+R
First of all, having two speakers doesn’t mean stereo, and that’s the first thing we should clear!
Let me tell you something, I do a lot of audio post-work and every time I get a stereo Wav or Aiff file from a video editor, everything is wrong: I receive stereo music mixed L+R, I get dialogue tracks together in a stereo track (boom on the L, Lav on the R), sometimes even L and R swapped, which turns out to be a mess, and you need to start guessing things. So, you definitely should know 2 tracks doesn’t mean stereo at all.
Let’s say you’ve got a mono track, like a bass guitar which is going to a stereo bus (a master bus, for example), despite it’s going to a stereo bus, that doesn’t mean the bass guitar became stereo, it just means it is playing the same, at the exact same level on the L and R channels, that’s L+R. If you, for some crazy reason, were to output that exact same bass guitar only to the L channel (that’s just one speaker), you’ll get the same mono result, only 3 dB softer.
Bottom line: L+R is playing a mono source in two speakers, and that will be perceived as 3dB louder than if it were played in just one speaker.
Now, think about a drum kit, you’ve got different elements and you’d probably wanna fill the stereo field somehow, so, you take the hats and pan them left, the floor tom to the right, rack tom a little to the left, kick and snare in the center, and overheads hard-panned to left and right. Now, you’ve got different elements coming stronger from different channels, probably more similar to what you would hear if you were standing right in front of the live drum kit, and that’s stereo!
Stereo mimics the way we hear, we have 2 ears with a head between them, we hear some sounds coming from the right, and some from the left, and that’s how stereo works. On the other hand, L+R is just that: all sounds coming both from left and right with the exact same volume, so our brain perceives them like if they were coming right from the center.
Checking Mono Compatibility
There are some systems that will playback in Mono, and you should always check that your stereo mix translates well in Mono. Think about AM Radio -yeah, that’s still a thing-, analog TVs -some TV stations still broadcast in Mono-, cell phones -most cell phones have just one speaker, and guess what? that’s Mono!-, most clubs and PA systems are set up to be Mono, despite the number of speakers, and the list goes on.
So, if you got a lot of stereo elements, and especially stereo effects like reverbs and delays you need to check how your mix translates to Mono, it’s very likely that listening in mono will reveal phase issues and you might not hear some elements that were so clear in stereo, especially on the low end and the high end. Now, it’s time to make decisions. You should be asking yourself questions like “Where will my mix will be played the most?” if your answer is TV or clubs, you should go back and fix those phase issues, maybe your answer is headphones, then you might not care that much about those phase issues.
Anyway, always remember the better your mix translates to mono, the better will sound in stereo.
Setting the Stereo field monitoring in Mono
As crazy as it might sound, a very cool trick used by top mixers is to listen in mono when you are setting all your elements in the stereo field. Let’s say you are panning a guitar track and you are not sure where to place it, listening in Mono can be very helpful. While listening in Mono, start panning until you hear the spot where the guitar actually sounds best, now switch back to listening in Stereo, the result is great! I do this trick every time with hats and it always works, always!
You might wanna do this with all the elements in your mix. You will find that works great when switching back to stereo, and you already know it will translate well to Mono systems.
Mono mixes to stereo
When you know your mix will be played mostly in Mono systems, you might wanna pan everything to the center and just forget about the stereo field. Well, that’s a valid option, if it gets played in stereo, you won’t have any problems, it is just L+R, but, it might not sound very exciting, so, I wouldn’t recommend this practice. It is always better to be sure that a stereo mix translates well to mono than to have everything panned to the center.
Some time ago I tested and reviewed a very interesting plugin that is very helpful when it comes to add dimension to mono and stereo tracks, check it here: Stereo Finalizer.
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