Sage Audio demonstrates how equalizers don't just shape frequency - they also rotate the phase of a signal, and that phase shift can quietly undermine a drum mix you've already worked hard to align.
Using a drum mix with overheads, kick, and snare, the video shows how adding a high-pass filter to the snare shifts its phase relationship with the other tracks. The steeper the filter slope, the more dramatic the effect: at 18 dB per octave or greater, the phase can shift up to 180 degrees, introducing a resonant peak just above the cutoff and pulling the snare out of correlation with any other track that captures it, even faintly.
This is a common blind spot when mixing multi-tracked instruments. Equalizing one track in isolation feels routine, but when multiple mics are sharing the same source, an EQ move on one signal changes how it sums with the others.