Your Friend: Audio Compression - Mastering Tips

When I first began producing music, I barely knew what a mixer was. I had no idea how to use the mixer on FL Studio and I wasn’t very proficient with it for a couple of months. But instead of learning how to properly use the mixer, I ignored it and continued writing music. So what is the biggest thing I missed out on?

Audio Compression

Compression is an essential aspect of any type of music; be it live recording, studio recording, or completely electronic tracks. They all use audio compression.

“How does compression work, and where should I use it?”

Don’t worry, there’s an answer to both of those questions.

First, let’s cover how audio compression works: Sometimes people equate lowering a track’s volume level with adding compression to the track. It may be close, but these are not the same. Leveling only controls how loud a track is played on the master mix; compressing the track actually changes the track itself.

With leveling, the track does not change. Adding downward compression to the track changes the track’s signal (ie. the recording or instrument) by taking out gain and volume, while upward compression adds gain and volume to the track. If you want to get nerdy about it, it changes what is heard from the waveform by decreasing the dynamics of the wave.

Terminology

There is plenty of jargon that gets thrown around when music compression is brought to the table. Some of the key terms you’ll want to study are threshold, ratio, attack, release, knees, and makeup gain. Threshold, attack, and release are all things you can find on a Limiter but I’ll go over those quickly. Read on…

Threshold is the level (measured in dB) at which the compressor will treat the signal. The lower the threshold, the more of the signal will be compressed.

Ratio controls the amount of automatic gain reduction the signal receives. If the original recording went 3 dB above the threshold and the ratio was set to 3:1, the output will be 1 dB over the threshold. Respectively, setting the ratio to 2:1 would half the gain after the threshold has been topped.

Attack and Release are a bit more complicated. Suffice it to say that attack decreases gain when the signal gets louder and release makes the quiet parts go back to the original volume.

Knees dictate how fast the compression hits in after the threshold is crossed. A soft knee will ease in the compression over a bit of time, while a hard knee will apply the compression immediately after the threshold has been breached.

Makeup gain is used to add or decrease gain after the settings listed above have already been set. You can add gain back into the signal if the current settings have the track sounding a bit empty, or decrease the gain (by going into the negative numbers) if your track is still too wild.

From one producer to another, I rarely find a reason to add gain back into the track after compression. The problem with using the makeup gain to add gain to the signal is that after you reach a certain point, the track sounds awful and airy.

If you have no experience with compression, I recommend using a compressor plugin, one of the best I’ve used so far (and I’m sure many others can attest to this), FabFilter Pro-C2. This will grant a much louder sound without the impurities and uncontrolled wave dynamics of the uncompressed track.

Who uses compression?

…the answer is everybody. Everyone and anyone who has a good producer, or is a good producer uses compression. No questions asked. Maybe they don’t all understand exactly how it works, or why it works, but they know it works.

Where compression is used most might surprise you. I used to think vocals got the most audio compression, or maybe bass guitars. However, in my time with music and personally mixing several people’s sounds, I find that the drums are easily the most compressed. Specifically, cymbals and high-hats receive the most amount of gain. If you have ever played the drums, that should make a great amount of sense.

Check: Best Free VST Compressors

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