Understanding the difference between mono or stereo can help you craft mixes with more depth and space.
The main difference between a mono (monophonic) and stereo (stereophonic) recording is the channel numbers used in recording and playback. With a mono signal, we only need a single audio channel to playback the sound. With a stereo signal, we use two audio channels to playback the sound.
Now let’s dig in a bit more and explore the differences between these two types of recording:
In the modern world, stereo has almost wholly replaced mono, as stereo recordings have a far superior audio quality. For consumer listening enjoyment, where a person is sitting in front of two speakers or wearing headphones, we often want stereo sounds to provide a sense of space and width.
However, there are times when mono is helpful. In large live show venues, engineers arrange various speakers to reinforce the sound across the listening region. Because it is difficult for people to have relative access to both the left and right speakers in this instance, mono is much better.
As for signals in mixing, the argument of which one is better depends on the sound. A single vocal, for example, only needs to be in mono, as it is one voice. A keyboard, which is comprised of many different sounds ranging from high to low, might be better to record in stereo, as you can capture the width of the instrument. In a busy mix, however, you may want to collapse a stereo instrument to mono to save space.
In a mono recording, we capture a single sound source with a single microphone. In a stereo recording, we capture a single sound source or multiple sound sources with two microphones. A vocal recording is an excellent example of a mono sound source.
You simply stick a microphone in front of a vocalist and record their voice, which is a single signal.
When you play a mono recording back on a stereo system, you get what is known as dual-mono. With dual-mono, the mono recording is played back equally in the left and right speakers.
When recording in stereo, you must use two microphones. More often than not, a stereo recording has one microphone panned to the left, and one panned to the right. As you can see in the acoustic guitar image below, the recording engineer placed two of the same microphones in front of an acoustic guitar.
One microphone picks up the body of the guitar while the other picks up the strings. When played together, one panned left, and one panned right, they give the guitar a wider stereo image.
In a mono playback system, you get sounds from both the ‘left’ and ‘right’ playing in one, localized place. In a stereo playback system, you get sounds from both the ‘left’ and ‘right’ spread across a stereo field in their respective positions.
Stereo systems create what is known as sound source localization. This idea refers to the human brain’s ability to locate a sound source’s position within a physical space. If your friend yells at you from down the street, for example, you’ll know from which direction that yell is coming from.
Stereo playback works similarly, providing the listener with two distinct sources of sound: The left speaker and the right speaker.
Stereo playback systems trick the brain into localizing sounds using an array of variables to differentiate the left and right speakers, including:
- Frequency differences
- Timing differences
- SPL differences
- Dynamic differences
- Reverberation amount
If the left and right speakers play the same sound at the same time; however, your brain is led to believe that sound is coming from the center. We refer to this concept as phantom mono, as the sound sources are panned out to the sides, though they sound as if they are centralized.
When it comes to audio differences that are qualitative, mono playback tends to sound punchier and direct. However, instruments tend to compete for space a bit more, as mono mixes layers instruments atop one another. Stereo playback creates the illusion of space, giving you a more exciting soundstage to work with.
How do I convert mono to stereo?
There are many tools that you can use to convert mono audio to s00tereo audio, though one of our favorites, as well as one of the most popular tools to do so, is Audacity.
Once you have Audacity downloaded and open, click the “File” tab and click “Open” from the menu. Find the mono audio file that you want to convert and highlight it. Click “Open” to import that file into the Audacity program.
Press “Ctrl+A” to select your audio track. Click “Edit” up at the top and select “Duplicate” from the menu. Click the left arrow on the original copy of your mono audio and hit “Left Channel.” Next, click the left arrow on the duplicate of your mono audio and hit “Right Channel.”
Lastly, click the arrow on the left of the original track and click “Make Stereo Track.” Once you click “Make Stereo Track,” your audio will merge into a single piece of stereo audio.
What is the use of mono audio?
Important elements, which should be heard in both speakers, should be placed in mono. When you only have stereo elements filling up the left and right speakers of a mix, you get what we refer to as Big Mono. Big mono is not appealing and often decreases the feeling of width.
With mono audio, we have the ability to place things in the center of a mix or to the left and right. When you have various mono elements spread across a stereo field, you create an illusion of width. Check this post that will explain to you Why Should Drums Be In The mono.
Producers and engineers often place mono elements such as vocals, bass, kick, and snare, directly up the center of a mix. The reason for this is that it creates the same impact coming from both the left and the right speakers.
We also tend to keep elements with low-frequency information in mono. Bass frequencies have tons of low energy, meaning they move a lot of air and take up more space in a mix. If we keep these frequencies in mono, we have more control over the space in our mix. Plus, many subwoofers are already in mono. Keeping your bass in mono gives you better control over how it is played back on various audio systems.
Is mono audio bad?
In new recordings, we don’t want to use mono if the mix is sparse. For example, let’s say we have a solo piano arrangement. The sound would be far more impressive if we allowed the piano to live across the stereo field from left to right rather than keeping it contained to the center.
If you think about old mono tracks from the ’60s, there is a lack of space. All of the instruments and vocals feel stacked atop one another. In terms of width and depth, this stacked mono sound isn’t nearly as impressive as a wider stereo image.
The same thing goes for choral arrangements, drum set recordings, or solo acoustic guitar recordings. In short, it is good to consider that mono audio might not be the best choice for very sparse mixes.
Should I have mono audio on?
There are plenty of reasons to use mono when mixing. Some of the top engineers mix almost completely in mono.
Here are a few reasons to utilize mono:
- EQ With Ease
When listening in mono, you can tell when two elements start to fight for space in a mix. Elements that have frequencies masking one another are much easier to hear, allowing you to make better EQ decisions within your mix.
- Better Balance
When listening in mono, it is much easier to achieve a better balance between instruments. Essentially, you narrow your focus to position the volume of each instrument in a mix without having the distraction of the stereo field to worry about.
- Less Ear Fatigue
Mixing in mono allows you to mix at lower levels. You’ll be able to trust your ears much more this way. When mixing at lower levels, you reduce ear fatigue. In return, you can work on a mix for much longer when your ears are in good condition.
- Spot Phase Cancellation
One of the best ways to spot phase cancellation in a mix is by summing the mix to mono. It can be quite difficult to hear phase issues when listening in stereo. As soon as you check your mix in mono, however, you might hear a sound get thinner or disappear completely. By checking your mix in mono, you can avoid phase issues that might hurt you in the future.
When setting up stereo sound, you want to make sure that your speakers are equidistant from one another so that your listening position is directly in the center of them. One of the best ways to set up stereo sound is by using the equilateral triangle technique.
The idea here is that the length between both your speakers, you, and your left speaker, and you and your right speaker, is all the same. This way, you take in the signals coming from the left and right at the same time.
It is good to make sure that your listening position is at least two feet from the speaker setup as well. If you are any closer than two feet, you won’t take in the same depth of the virtual soundstage.
Make sure to avoid symmetry on the right and left if possible. While it is good to have your speakers the same distance from one another, it is not good to have the same amount of space on either side of the speaker, especially if the outsides are walls or corners. This creates nasty room reflections that can hinder your mix.