The best mono compatibility with stereo tracks

Often I find myself stressing over getting the best mono compatibility when mixing. When I turn that mono button I’m often wondering what to do.

Do people split stereo tracks into mono

Do you reduce the stereo width to a lower value to have better mono compatibility

I read a recent article about this and was told just do your best and not worry about it too much.

Anyone have any suggestions

What is your target? You want your mixes to still sound good when played over an AM table radio? That used to be the justification for mono compatibility, but I’m not sure what the use case is these days. I do have a table Internet radio type device which is mono, but I don’t worry about the sound quality of that too much, it is basically to play background music, it has pretty limited low and high frequency response, mono compatibility is probably the least of concerns for that style of device.
That is the only mono device I have, I haven’t seen a TV with mono speakers in about a decade and a half, cars have had stereo instead of mono since around 1970, I don’t think any of the personal audio devices are mono, everything uses stereo earbuds now. My point being that “mono compatibility” is in large part a “when I was a kid…” type story that older guys tell you. I mean, have you personally ever thought to yourself “wow, I thought that song sounded better than that, it really doesn’t sound good on that mono .”
Maybe smart speakers. Those little Alexa things (Amazon Echo?) are mono, aren’t they? So I guess if you care how good something sounds on a 3" puck sitting on the table it could still be a concern.

Not generally, no. Mono tracks are for sources that are recorded from a single microphone or single output jack, stereo tracks are for sources which start out with two channels of information for some reason, either a stereo microphone configuration, or electronic instruments which already have panning set, like a drum machine or synthesizer which has panning configured. If you have stereo tracks you generally want them to stay joined so that edits, EQ, reverb sends, etc. stay joined between both sides. If you split a stereo track it just makes twice as much work for you.

Has nothing at all to do with mono compatibility.
There are two aspects to mono compatibility, technical and artistic.

I think technical is the easier of the two to understand, because that is essentially “does the signal change when the L and R channels are added together?” For a source that started as a mono channel and was panned L and R, there are only amplitude differences between the two channels, so when you add the L and R back together, you are back to the original signal. So perfect mono compatibility.
If you add a processor (plugin) before the panner, then again you have a single source signal that is only modified in amplitude to the L and R outputs, so perfect mono compatibility when you add them back together.
If you add a stereo processor after the panner, then you have to understand what that processor does to the phase of the L and R outputs, for example a stereo chorus might shift the phase of the L and R sides either independently, or in opposite directions, so when you add the L and R together you get shifting cancellation. It might sound OK, or it might sound annoying, sometimes you just have to try it and see.

Which gets to the artistic considerations. Human hearing involves processing in the brain, not just the ears, and one of those processes evaluates direction of arrival and creates internal models of sounds to determine where to split attention. For something like a musical instrument with reverberation (either added or recorded at the source), that can mean that what sounds perfectly appropriate when the instrument or voice is at a certain level and direction, with reverb spread across both channels, sounds like too much reverb when the instrument or voice and all of the reverb come from the same direction.
Or the previous example, a stereo chorus might sound nice when spread between L and R, but just makes a shifting comb filter (if you are not familiar, it describes the picture of the frequency response, up and down like the teeth of a comb) when combined into a single channel.
In those cases you just have to decide whether you care that the mono mix doesn’t sound as good, if not then say good enough is good enough and move on, or if you do then figure out how to tweak the stereo mix slightly so the stereo mix still sounds good, and the mono mix sounds better than it did before. That just takes experimenting and experience.


Well I’m always advised to make sure mixes are mono compatible, also some plugins have meters that let you know where your mix stands and I do have a program called expose which lets me know a lot of technical info about my mix.

But I have heard some engineers say they don’t care about mono mix but I’m wondering should I care or not.

If that isn’t followed with a “because …” phrase explaining why you should do that, you should ask whoever is advising that “why is that?” and see what explanation is given.

To repeat my earlier question:

I gave an example of the only modern device I could think of which is mono (Amazon Echo Dot, with a single 1.6” speaker). Can you think of any other single speaker devices? Elevators, probably.
So are you concerned with how well your mixes translate to Amazon Dots and elevators? If you are then get a small speaker enclosure with a 1-1/2" speaker and listen to your mixes to see how well they come across. Something like that is so radically different than a pair of stereo two-way or three-way monitors that it is hard to know other than checking.
Personally I am skeptical of the benefit of trying to optimize for a sub-2" speaker, it doesn’t seem like someone listening on a single speaker that small really cares about audio quality, it is just for background sound.

lol I understand. I think that I guess the main idea I’ve been hearing to mix in mono compatibility was also to ensure your mixes play its best on many different sound systems and I guess more better as a professional mix

That just takes listening to mixes on a lot of different systems and starting to gain intuition on the range of differences you are likely to encounter.
But if all of those different systems are stereo, then mono compatibility is just a waste of time. I think that is just one of those things passed down as tradition that used to be important when TV’s had mono speakers, and some cars still just had a single speaker in the middle of the dash, and people had pocket radios instead of phones with earbuds. It just became common wisdom for so long that a lot of people stopped thinking about whether it was still relevant or not.

Ok I am procrastinating a bit on a project but gonna have to play devil’s advocate a little here.

Mono Compatibility isn’t really a waste of time honestly. Just because a system has two speakers doesn’t mean that it is stereo. You have incorrectly set up systems to start with, or systems that the speakers are so close together that there is no way that you will ever hear stereo or get much differentiation between what your ears here if it is in front of you. There are still many cell phones with a single speaker as well.

But even beyond that, when playing over a professional reinforcement system, the system may or may not be stereo, mono, LCR, or some combination of all of the above. In fact it is incredibly common for professional reinforcement systems to be mono and have multiple speakers for coverage, not for stereo image.

I have repeatedly run across situations where clients ask why their track doesn’t sound good, and explaining mono compatibility gets me black stares of, well isn’t there two speakers, how is this NOT stereo, but the truth is for stereo in large venues, each reinforcement driver has to have complete coverage of the entire space within about 30mS of each other at most (And truthfully less ideally) and fairly even levels. This is far more difficult in larger spaces than most people realize, so mono compatibility becomes far more important. Not to mention that even if a true LCR or Stereo system is involved, the delay fills are almost always still mono fills, which while it would maintain the appearance of stereo if set up correctly (Our brains are just weird when it comes to psychoacoustics sometimes) if you are piping a track with lots of phasing problems due to poor mono compatibility through it, you will have issues.

And even outside the world of professional reinforcement, how many times have you heard background music in a restaurant, store, etc. Many of those systems are still mono as well.

So I would argue mono compatibility is still important, just not for individual systems.


I agree, I still try to have the best mono compatibility as I can but sometimes it’s hard and I get kinda stressed about it

FabFilter did a nice three-part tutorial on mono compatibility; you can access it and other training videos here: FabFilter Video Tutorials. Some of these tutorials are specific to FabFilter plugins, but most of them are broadly applicable and there’s a lot of good info for beginners and experts alike.

I’ll check it out thanks for sharing this.

Seablade is absolutely right. To complement what he said, many mono systems in the smaller clubs and bars, either legacy or poorly wired, sometimes just the extra rooms.

Finally, if you ever have your music cut to vinyl, you’d better have mono-compatible lows because the cutting engineer will certainly make them mono.

For me what’s hard is after I create something via virtual instrument or drag in a nice loop I like when I flip to mono for that sound, the sound kinda disappears a bit and for me I don’t know what to do moving forward, only things can do is reduce the width then it becomes more mono but then obviously it lost Stereo width and sound quality

Well that is the balancing act, but you also hit it on the nose, some VIs and Loops are created ignoring mono compatibility, and the best option might be to not use those particular sounds, but to either find others or create your own. Anecdotally becoming more of a problem as time goes on, and part of it is similar thinking to what was expressed above (No offense intended to @ccaudle who provided a well reasoned explanation) : ‘Well none of the devices I can think of are mono, and I want the best stereo sound possible, so I am going to ignore mono’. This is not necessarily wrong, but is a choice to make and you should consider where you want your music to sound good on when listened to and pick your balance.


What I should do is listen to a bunch of commercial masters and see how mono compatible thru are by using the mono button.

You might still be confused after doing that, the reason is that it’s a big diversity of mixes that are targeted to so many different mediums or venues while others try to make the mixes sound good on as many different devices as possible. As mentioned above: You must know the target and in addition, you must also know what you want with the mix. It’s really no idea to work with this if you don’t have a feeling for the material you have, at least in my opinion.

Mono compatibility is in general a good thing, that helps the needle in a turntable to stay in place on the LP, and of course, it helps on countless devices with only one speaker.

My approach to this is that I also spend time mixing in mono, which ensures that every instrument has space and if it sounds good there, then it will in general sound good everywhere. I do not care too much about the phase-correlation meter, but keep an eye on it, if it sounds good, then it is in general good.

From what’s written on this forum and elsewhere on the 'Net, you probably know very well why you should think about mono compatibility or not. It really boils down to a very few things: Let your ears decide, make sure you mix regularly and as often as possible, and have an understanding of the material/artist and audience.

Interesting. In earlier days the recipient used tone control (or EQ) to adjust the sound to the environment. I get the feeling these days that fitting the sound to the environment has become a duty of the music producer ­— and virtually impossible given the wide range of play devices and environments.

That only gets so far though. That is why studios have big monitors mounted in the walls, and usually smaller monitors somewhere near the console, and sometimes small little speakers that can be connected. I’ve even heard of studios that have an Orban radio processor so you can hear what the mix will sound like after all the crazy EQ and compression that FM radio stations do to the music.

But to repeat myself again, you need to know your target. If you are mixing a pop song you probably care what it sounds like through FM radio processing. If you are recording free jazz, or modern classical/art music, then probably what it sounds like on your local pop station or played through the mono sound system before the local rock festival isn’t much of a concern.
Likewise if you are mixing EDM what it sounds like on a big club system or the local pop or hip-hop station is probably very relevant.
Even in that case I think you should still listen on a good (i.e. flat frequency response, low distortion) system to know what it “really” sounds like. Noted mastering engineer Bob Katz phrased it something like some systems have too much bass, some too little, some are too bright, some have too little treble, you can never make it sound perfect everywhere, but if you make it sound good on a good system with flat response and low distortion, then you should be in the middle, and have the best chance of making it sound reasonable everywhere.

To go back a little more closely to the original discussion, I was thinking mostly in terms of traditional pop recording where you have a lot of mono tracks and using panning to adjust stereo position, that style is intrinsically mono compatible until you begin introducing time modulation effects (such as the chorus example I gave earlier).

And apparently whatever source material mrskytown is using:

In a case like that you just have to decide whether the “disappears a bit” changes the sound enough that it removes whatever fundamental quality you liked about it, and whether that is important enough that you just don’t use that sound or loop.
And reducing the width isn’t really a solution, except in the sense that it will make the stereo mix closer to mono, if mixing the L/R channels to mono changes the sound, reducing the width is just going to start that process for you in the stereo mix, I don’t think it is going to change the end result. I haven’t checked the code, but I expect that reducing the width is just mixing the L and R channels slightly, so when you combing to mono it just completes that process and the end result is the same as if you had not changed the width in the stereo mix.