Music mixing and equalizationPhase offset in EQ is the phenomenon where a boost/cut in any frequency band via an EQ shifts the phase of that frequency region to the amplitude difference.

In normal English, it means that when you a perfectly flat EQ (bypassed), all the frequencies in the spectrum are in phase with themselves. But once you disturb the amplitude of any frequency you induce a delay to that frequency in comparison to the “un-EQ’d” frequencies.

Some people like this sound (aka: it’s quite an analog type of phase shift and many digital EQ plugins try to replicate this shifting). Some other people prefer linear-phase EQs (where the plugin designer tried to minimize the phase shifting that occurs).

Personally, I prefer whichever tool works best. Plugins like Pultec and others are analog heaven and impart their own flavor on the sound. Other plugins which are linear-phase are more used for surgical correction of tone.

Bottom line: play with your EQs and use what you like best!