Step 2: Linear or not
Now in more detail about the linear phase mode and all the pros and cons of use of such equalizers in audio mixing and mastering. First, far from every equalizer in your favorite DAW has such an option that’s why in most cases it won’t suit final track processing, actually mastering. As an exception I can name a linear phase equalizer as part of Logic. The algorithm of its work has already been indicated in the title so you can easily use it in audio mastering services online. To choose an appropriate EQ out of non-stock ones is a lot easier as there’re a great deal of developments towards linear phase EQ processors. There are a great many equalizers suited for it, the same Fabfilter’s Pro Q which allows you to work in both the linear mode (herewith you can pick out the length of delay out of five options offered, starting with minimal to the highest possible) and in the ordinary one with the maximum economy of CPU (ideally for mixing).
The phase shifting of its own accord isn’t bad, and non-linear equalizers are often used in audio mixing due to specific coloration added to the sound. I would name Ableton’s stock EQ as a typical representative. It has zero gravity for a processor and specific focusing on upper midrange. But in most cases this approach doesn’t suit audio masteringgoals so you’d rather make a choice towards linear phase equalizers. Thanks to special algorithms they add absolutely transparent sound in online mixing mastering services with EQ and play more technical role in cleaning a track from all excess stuff without applying its own coloration. We don’t care about resource-intensity and delay as most of processing has already been done by an engineer.