Have you heard about phase cancellation? It’s when two sounds meet and get quieter or even stop. It’s like two waves in a pool hitting each other and stopping. If you make music or work with sounds, this is important. You need to put microphones and speakers in the right places to avoid it.
Want clear and good sound? Learning about phase cancellation can help!
What is phase cancellation?
Phase cancellation occurs when sound waves clash, causing interference. This happens when similar sounds mix and cancel each other out.
You can call it destructive interference too. It’s when related sounds are out of sync and result in a problem.
If this sounds puzzling, don’t fret. I’ll explain it simply, one step at a time.
How does phase cancellation happen?
Phase is like where a sound wave is in its cycle. Picture it as the wave’s left-to-right position on a chart. We measure it in degrees like a circle, because sound waves repeat.
If you shift the phase a lot, the high and low points of the wave flip, which we call “180° out of phase.”
When you play the original sound with the 180° out of phase one at the same time, they cancel each other out, and you hear nothing!
Because they’re at opposite positions, the wave’s ups and downs add up to zero—complete cancellation!
But in everyday situations, it’s not usual for two sounds to cancel each other completely.
Instead, what often happens is that two sounds have similar parts that make some of the sounds go away.
This can make the sound lose some of its bass or power and sound thinner.
So, if you mix two sounds and they sound weaker instead of stronger together, it might be because of phase cancellation.
Common phase cancellation issues
But sometimes, it can be hard to tell when phase cancellation is happening.
To make it clearer, here are three common situations where you might notice phase cancellation:
1. Stereo widening plugins
Some music tools can make your sound seem wider in stereo by doing clever things.
They often tweak the timing or how sounds match up between the left and right sides. But, sometimes, these tweaks can cause trouble when people listen in mono (like on older devices).
Making sure your music works well in both stereo and mono is important for a great mix, and many creators consider it essential.
If you want to learn more about this and other stereo sound tips, check out our series on stereo mixing.
2. Recording with multiple mics
When you use more than one microphone to record something, there’s a risk of phase cancellation.
This happens because each microphone hears the sound at slightly different times, and this can make the recorded sound not match up well.
Phase cancellation can also occur when you use both a microphone and a DI box to capture sound. This often happens when recording bass guitars, where you record the sound from the instrument and an amp.
3. Processing correlated signals
Lastly, when you use tools like EQ to adjust sounds that go together, it can sometimes cause phase issues.
It might surprise you, but many usual mixing actions can change how the sound lines up.
For instance, if you apply a strong EQ with lots of adjustments, your sound might not match well with other related tracks.
How to avoid phase cancellation
Now that we’ve covered the basics, let’s look at the main ways to handle phase cancellation.
1. Avoid phase issues at the source
The top solution for phase problems is to prevent them right from the start.
It might seem a bit tricky, but once you learn to spot signs of out-of-phase sound, you can stop it before it becomes an issue.
Whenever you’re recording two sounds that might overlap, try flipping the polarity to check if it makes a noticeable change in the sound.
Speaking of which…
2. Try inverting the polarity
Mic preamps and DAW mixer channels often come with a switch to change the polarity.
This switch looks like a circle with a line in the middle, and it flips the negative and positive parts of the sound.
This turns the sound’s phase around by 180 degrees without making it late.
If your sounds are almost 180 degrees out of phase, using this switch can help.
But as I mentioned before, it’s best to get your sound in phase when you record it, even if that means using the polarity switch during recording.
3. Use a phase correction tool
You don’t always have to completely flip the sound to fix phase problems.
Instead, you can either move the microphones physically or use a special tool on your computer.
These tools just shift the sound a tiny bit earlier or later.
They let you adjust how the sounds fit together more precisely.
Here are some useful tools to try:
- Sound Radix AutoAlign 2
- Waves inPhase
- SSL X-Phase
- Melda MAutoAlign
4. Try other processing modes
Some fancy digital EQs have settings that don’t mess up the sound timing as much.
If your EQ is the issue causing the sound problem, you might want to try this.
But here’s the thing about “linear phase EQ.”
When you use it, it delays the sound a little compared to other tracks.
This can fix the problem from the EQ, but it creates a new one.
The EQ can make some sound start wiggling before the main sound, which is a natural thing for EQ filters. But it’s a problem when it happens before the rest of the sound!
This is called “pre-ringing,” and that’s why people are careful when using linear phase EQ, especially for low-pitched sounds.
If your EQ has a linear phase mode, you can give it a shot if the filters are causing problems. But remember, it won’t work perfectly every time.
5. Process-related sounds on a bus
Lastly, you can steer clear of these issues by using the EQ on all your related sounds together in one place, like an aux return channel.
This way, any changes the EQ makes to the sound’s timing will affect all the tracks the same way and won’t mess things up.
No more phase issues
Destructive interference might sound complicated, but it’s a regular thing with signals.
No need to stress; you can fix it once you understand how it works and what to do.
If you’ve read this article, you’re off to a great start in avoiding phase problems in your music mix.