How to Use Compression Plugins (and What They Actually Do)
Compression plugins make up the backbone of mixing, mastering, and general audio engineering. Unlike other plugins, experimenting with the knobs and dials will sometimes leave you with more questions than answers regarding what they actually do.
There’s a common misconception that compression plugins increase the loudness of audio. When you combine this with the perception that louder equals better, you get the perfect recipe for misuse and overuse of compression.
But don’t fret; we will do away with the mystery surrounding compression so that you can harness its wonders and avoid draining your music of its sonic vitality.
What Does Compression Do?
Compression plugins reduce the level of the loudest portions of a sound and increase the level of the softest parts. They do so by compressing the audio signal that goes above a specified (volume) level or threshold. In other words, compression reduces the dynamic range of a sound leading to a more even sound.
While this is one of the core functions of compression, you may generate different sonic effects and characters when you use the parameters of compression plugins in different ways. So, not only can you glue together and even out the dynamic range of a track or group of tracks, you can also add punch, excitement, and “oomph” to diverse audio elements.
Compression Plugin Parameters
Now, we’ll look into how each compression setting works.
1. Threshold
TheThresholdis measured in decibels (dB) and is usually presented as a negative range of values. This is the case as volume values that go above0.0 dBon any audio signal results in clipping (waveform distortion), which, in most cases, is undesirable. If clipping is affecting your audio, check out our guide onhow to fix audio clipping in your DAW.
When you set a threshold value of -25 dB on a given track, compression will only occur on the portions of that track where the volume goes above -25 dB. Generally, a low threshold value (e.g. -30 dB) will lead to more compression of an audio signal and vice versa. However, a low threshold value on one track may not be low enough on another.
For example, very little compression will occur if a track mostly plays at -32 dB, and your threshold value is set “low” at -30 dB. Thus, you should choose the threshold value in line with your track’s dynamic range.
While certain instruments may benefit from heavy compression, you may want to use a more subtle approach and only compress the loudest portions of a track.
Bear in mind that any volume changes you make to a track after you use a compression plugin will change the degree of compression applied.
While the threshold relates to what dB level you want to compress from, theRatiorelates to how much compression you want to apply.
Let’s go through some examples to see how the ratio works.
If you set your ratio to 3:1, and your audio signal exceeds the threshold by 9 dB, then the signal will be reduced to 3 dB over the threshold (9 divided by 3). This also means that the sound experiences a gain reduction of 6 dB via compression.
If your ratio is 8:1, and your audio signal exceeds the threshold by 16 dB, then the signal will be reduced to 2 dB over the threshold. Here, the gain reduction is 14 dB.
As you can see from the gain reduction value, lower ratios lead to more subtle compression, and higher ratios lead to the opposite.
3. Make Up Gain
The gain reduction value is also useful to determine the exactMake Up Gainto apply within your compression plugin.
As we’ve discussed, compression actually lowers the overall level of your track(s). Sometimes you’ll hear an automatic increase in volume when you activate a compression plugin. Switch off theAuto Gainfunction to give yourself more control.
TheMake Up Gaindial lets you make up for the level decrease post-compression. If your compressor displays the gain reduction (e.g. -4.3 dB), increase yourMake Up Gaindial by that amount. If you don’t, bypass (switch off) your compression plugin and make note of the original dB level. Then, switch it back on to see the reduced value. ApplyMake Up Gainso that the values are equal.
This can be an important practice as otherwise, your ear will naturally think that the louder sound is the better sound. Once the pre-compression and post-compression dB levels are equal, you’re able to more accurately assess if your changes are improving the sound or not.
TheKneeparameter ranges from zero to one, where zero is a hard knee and one is a soft knee. This setting regulates the character of the gain reduction affecting an audio signal.
When an audio signal goes above the threshold, a hard knee causes a sudden reduction in gain; this is the default for most compressors.
A soft knee, on the other hand, leads to more gentle transitions: gradual compression plus an increase in ratio occur as the signal approaches the threshold.
TheAttackparameter, measured in milliseconds (ms), lets you control how quickly the audio signal is compressed once the threshold limit has been exceeded.
A fast attack time can work well to tame excessive peaks in volume, yet it can also eat up the transients (the initial burst in a sound wave) of a sound to its benefit or detriment. A slow attack time can let such transients through while compressing the rest of a sound.
6. Release
TheReleaseparameter, also measured in milliseconds (ms), controls how quickly the audio signal goes from compressed to uncompressed. The best release setting for your track will largely depend upon the tempo and the character you’re after.
A slow release can end up compressing the following transients (the next notes or hits) if it takes too much time to reset to uncompressed. A fast release can generate a pumping effect that could be a welcome addition or distort the natural sound of a track unpleasantly.
To tighten up the audio at the beginning and end of your audio regions, check outhow you can fade all your audio regions in seconds in Logic Pro.
Add Character and Punch to Rhythmic Audio
Now that you have the basics of compression covered, we’ll show you one way you can add some punch to the rhythmic elements of your audio.
The key to adding punch to a snare sound, for example, is to apply heavy compression after letting enough of the transient pass through uncompressed. To do this, you will need to use a slower attack time.
Before you slow down the attack time, set a sufficiently low threshold and a high ratio (e.g. 7:1). Start with a fast attack and release time and listen to your track on loop.
Gradually increase the attack time until you hear enough of the transient pass through, and increase the release time until it matches the tempo of the rhythmic hits. Don’t forget to use the Make Up Gain to make up for the gain reduction, and you should be left with a punchier and tighter-sounding percussive hit.
If you want to further expand your creative toolset, look intohow to reverse audio in Logic Pro.
Make Your Audio Stand Out With Compression
Compression lets you tighten up and enhance the sound of individual tracks, mixes, and masters. It lets you reduce the dynamic range of a sound, glue together multiple tracks, and boost the character of different audio elements.
Use fast attack and release times, a hard knee, a low threshold, and a high ratio for aggressive compression. For subtle compression, do the opposite. Once you’ve grasped the basics, experiment with different settings to refine your audio, but beware; don’t overdo it.
Complete all your fading edits in seconds with the right tools in Logic Pro.
Tor spoiled me forever.
These are the best free movies I found on Tubi, but there are heaps more for you to search through.
Don’t let someone else take over your phone number.
Goodbye sending links via other apps.
These plugins will make you wonder why you used Photoshop in the first place.
