Difference between Linear Phase Eq and Regular Eq

Hello and welcome to this week's article!
Today we're going to focus on a topic that we have mentioned in many occasions, but that we never really explained yet: what does the term Linear Phase Eq and Regular Eq mean.

Let's start with this assumption: Regular EQ’s have phase shift between the different bands. When we boost or cut a certain area, that frequency range is technically delayed by a tiny amount, due to the way the equalizer itself works.

Linear-phase EQ, instead, compensates this delay keeping all the frequencies 100% in phase (it basically anticipates the wave of a certain time to correct the phase shift). In other words, all the frequencies pass through the EQ at the same speed, resulting in zero phase issues between bands.

The basic question is: "if they have created a way to prevent the phase to shift, why don't everyone uses just linear phase eq?"

the answer is because it consumes more cpu resources and, especially, because it creates a "pre-ring", which means that by correcting the phase variation it creates a part of the wave that actually starts BEFORE the peak of the transient, and this, for certain types of sounds as for example percussive drums, it can ruin them.

The conclusion is that linear phase eq is best suited for certain instruments in which this problem is less apparent (like acoustic guitars) and less for others, and we must try it and compare it with the regular one in order to understand on which instrument it brings a benefit and on which one not.

About the mastering phase, finally, there are different schools of thought, for example many producers likes the result obtained with the Waves Lin-Mb, a linear phase multiband compressor, because they think linear phase sounds more transparent, while other engineers think that the "pre-ring" downside can ruin the mastering, especially if we are speaking of a heavily percussive track.

As always, it depends and we must trust our ears.



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