Researching the process of at-home music mastering can lead you down a lot of rabbit holes. One of them is the concept of mono mastering. It gets thrown around by mastering gurus and YouTubers as an expert trick to improve all your tracks. But is mastering in mono really the best (or only) way that you should be finishing your songs?
In this article, I want to explain the argument of mono vs stereo mastering and which to use. Hopefully, this will simplify the mastering process for my fellow D.I.Y. home producers.
Should You Master in Mono or Stereo?
So, should you be mastering in mono or sticking with Stereo method? In reality… use both; you should switch between mono and stereo while mastering your track. Mono really is a useful trick like the producer gurus say. But you do not want to master the entire song that way.
There are concise reasons to check mono signal during the final mix process. I’ll touch on them in the next section. But, in short, the best way to master a track at home is to:
- Work through it in stereo and get a first pass roughed out,
- Switch to mono so you check for anything amiss, then
- Go back to a stereo signal, to make sure you didn’t mess anything up in mono
And your final mix, the one that you export, should always be in stereo. Don’t bounce a file out in mono.
Now, let’s talk about why mono is useful…
Why Should I Mix and Master in Mono?
Mastering in mono allows you to check for two main issues in your track. They are:
- Frequency congestion, and
- Phase cancellation
Either of these issues can get masked by stereo output. But, if a person is listening back to your song on a mono speaker, then they’re going to notice these discrepancies.
That’s why you should check your mix in mono after the initial mastering has been done. It’s just a way to catch audio inconsistencies present on singular speakers.
Let’s look at those 2 issues in more detail.
1. Frequency Congestion
You may have multiple instruments, or an instrumental and a vocal take, that are taking up the same frequency space in your mix. If those tracks are panned away from each other, it can make them sound distinct and you won’t notice the problem. But listening to the mix in mono will squish all those parts together…and the result could be a muddy mess, where the instruments/takes are fighting each other for dominance and they all sound hard-to-hear.
All sounds are composed of frequencies at varying levels; and (almost) all musical sounds will have a dominant frequency range.
For example, your guitar part and your lead vocals may both have a dominant frequency around the 800 Hz level. If you leave them together at their dominant frequency, the two parts will sound cluttered…like the vocals just can’t seem to “reach over” the guitar and get the listener’s attention. Or the guitar sounds too “in the way” of the vocals.
Mixing in mono lets you hear all the frequencies ranges without panning, so you’ll know if two instruments/vocals are clashing for control of a given range.
How to Fix Competing Instrument/Vocal Parts
And how do you fix two tracks that are competing for the same frequency? Try one of these 2 tricks:
- Cut the problem frequency for the less-important instrument/part, and give it a slight boost in a second frequency range, or…
- Re-record the part in a different octave.
Let’s go back to our guitar vs lead vocal example: in this situation, you could ease the frequency congestion by:
- Cutting the 800 Hz level on the guitar with an EQ, or
- Re-recording the guitar riff an octave higher, or even
- Pitch-shifting that guitar part up or down with a plugin
In most situations, simply cutting and boosting frequencies with an EQ will do the job. That’s why I recommend that edit first.
2. Phase Cancellation
Phase cancellation is when two sound waves at the same frequency cancel each other out. This causes both of them to sound quieter and weak. This can happen easily if you take a single instrument track and widen it artificially using a stereo spread plugin. Or if you record the same instrument with two different microphones at the same time.
In many cases, you won’t hear the frequencies getting canceled out in the stereo mix. But, when checking the song in mono, you notice that the volume level of the affected instruments are significantly reduced.
How to Fix Phase Cancellation
So how do we correct a track(s) that’s suffering from phase cancellation? It depends on what caused the issue in the first place.
If the issue is caused by using two mics on the same track, then you can:
- Re-record the part with the microphones in an XY configuration. That essentially means the mics are right over top each other (but not touching) and pointed in different directions (usually at a 45-degree angle). Or…
- Just hit the Phase Invert Button. Most DAWs will have a button on each track that switches the polarity of a signal. Invert only one of the mic tracks. This will flip the track’s signal and remove the cancellation.
If the issue is caused by a stereo spread plugin, then try to:
- Fiddle with the stereo plugin levels while in mono. I’ve found that using too extreme of a spread can sometimes cause a cancellation issue. So try reducing the spread level. If that doesn’t help…
- Consider recording a dub of the track you want to spread, and manually pan each track to the sides. If it’s not an instrument you can re-record, you can also test out…
- Duplicate the offending instrument track, pan the two copies, and apply a delay effect to one of them. Just a millisecond of delay could resolve the issue.
How Do I Switch to Mono?
Most digital audio workstations (DAWs) should have a little button that switches a track (or the entire mix) from stereo to mono format. To master in mono, you’ll need to flip this switch to the mono position on your master bus.
In FL Studio, I believe there’s a slider below the panning control that lets you adjust stereo to mono. I use Cakewalk by Bandlab. In this DAW, the button is named “interleave” and looks like an hourglass on it’s side.
What Instruments Should Be Mono or Stereo?
Since we’re on the topic of mono vs stereo, I want to point out that not all instruments need a stereo spread. Some instruments (or, at least, their dominant frequencies) will make a track sound lopsided or weird if you pan them. These include:
- Kick drums,
- Bass guitars or bass synths,
- lead vocals
In general, you want to keep the lowest frequency instruments in your song near the center of your mix. You also want the lead vocal front and center so it gets the most attention.
But that’s just a generality. Feel free to break the rules as long as your song still sounds balanced. If you pan the lead vocal to the left, make sure another instrument of similar weight is panned to the right to keep the whole mix leveled.
In conclusion, your first pass of mastering should be done in stereo. But a mix should usually be checked in mono at least once before you export. This allows you to check for canceled or competing frequencies. Remember to put the mix back into stereo before bouncing the final track out.
Thanks for stopping in and I hope you found this article helpful. If so, then here are a few more topics that you may want to peruse: