The Science of Audio Saturation: How it Works

What Is a Saturator?

A saturator recreates the by-product of the limitations of analog recording technology, referred to as saturation. When recording to tape, pushing the signal too hard results in a type of distortion known as tape saturation.

There's also tube saturation, which has a slightly different sound that results from a vacuum tube in an amplifier being pushed to its limits. Both tape and tube saturation is pleasing to the ears, unlike digital clipping, which can sound harsh and undesirable.

The Science Behind the Sound

Saturation works by introducing harmonic distortion to your audio signal. When you saturate an audio signal, you're essentially adding overtones that weren't present in the original sound. These added harmonics can enhance the timbre and richness of your audio, making it sound more thick, vibrant, and full.

The exact nature of these harmonics varies depending on the type of saturation used. Tape saturation tends to produce even-order harmonics, which have a musical and warm sound. Tube saturation, on the other hand, produces both even and odd harmonics, resulting in a richer and denser sound.

From Analog to Digital

As the audio industry shifted from analog to digital recording, we lost the natural saturation that occurred in tape and tube devices. However, the character and warmth that saturation added to tracks was so beloved that digital emulations were created to mimic this effect.

Today, saturation plugins recreate the harmonic distortion of analog gear. These plugins often come with various types of saturation, such as tape, tube, and transistor, allowing you to choose the type of saturation that best suits your audio. Some of my favorite saturator plugins include Soundtoys' Decapitator, which is great for bass processing, Plugin Alliance's Black Box HG-2, which is perfect for mastering purposes, and FabFilter's Saturn 2, which provides an assortment of saturation algorithms.

Using Saturation in Your Mix

Saturation can be used to add character and warmth to your mix, but it can also be used as a dynamics control tool. By adding harmonics to your audio, saturation can make elements of your mix appear richer and louder without necessarily increasing their volume. This can help you achieve a more balanced and cohesive mix.

Try using saturation on your drums to add punch or on your bass to make it translate to consumer speakers. Vocals can also benefit from a touch of saturation, adding presence and character. When applied to instrument groups, saturation can help provide related sounds with a sense of cohesion, placing them in the same sonic space.

Saturation is a powerful tool, adding warmth, character, and depth to your mixes. Understanding the science behind saturation can help you decide which type of saturation to use in different situations. The stock audio effects included with your digital audio workstation (DAW) can get you started, but you may want to upgrade to a more versatile and robust saturation plugin down the road, like FabFilter's Saturn 2.