Linear phase or Non-Linear phase mastering is a REALLY REALLY important part of the mastering process that YOU need to know about… but what is it? This article will dive into what Eq is, the effects of phase shifts, and knowing when to use each type of Eq. Not all Eq is made alike… let’s find out how.

We first start off with talking about the technical parts of equalizers. When applying equalizers (Eq) to your tracks you are doing more than just increasing or decreasing frequency amplitude. The process of applying Eq also introduces a certain amount of delay (phase shift) to the signal. Without getting too technical; it is important to understand that in regard to Eq, the terms delay and phase shift are one in the same. With Non-linear Eq, when you make an amplitude adjustment you are also making phase shifts to the signal. Whereas, with Linear Eq, when you make an amplitude adjustment there should be no phase shifts to the signal… So what does that mean?

Let’s go to the lovely world of analog audio. Even as digital audio is taking over the industry; there is a demand for analog gear and for digital replication of analog gear, but why? When you talk with experienced engineers/producers/musicians who have extensive experience with analog gear they will all praise the “character” or “color” of certain pieces of gear. That is because all analog Eq (and their digital replications) are Non-linear and have phase shifts. It is the phase shifts that really give character and color to the sought after pieces of gear. Do you love the sound of a Neve 1081, API 500 series, or Pultec? Then you love the phase shifts from the changes in amplitude with these iconic pieces of equipment.

By contrast, a Linear Eq will leave the phase of each frequency alone as you make amplitude changes. As you may have guessed, Linear Eq then will introduce no color or character changes to the audio signal. It also helps to preserve the transients of audio signals by preserving their phase. Have you ever had an engineer say “I love the sound of that Linear Eq”… no, because Linear Eq is by nature very transparent. When applying Linear Eq the only changes you hear are the changes in amplitude for the specific band you are working with.

Now the question comes; how do I know which one is right for my project? Part of the answer may come from knowing what kind of processing was used during the tracking and mixing process. If you used gear with lots of character then you may want to preserve that sound with Linear mastering. However, if your tracking and mixing process happened in the box with sterile sounding plugins, then maybe Non-linear mastering will give your tracks some life. Knowing the difference and how to apply both Linear and Non-linear Eq is an important part of getting the sound you are looking for.