those sexy curves again

proportional EQ curves

What constitutes those smooth sounding equalizers some are raving all about? In fact the answer is pretty much simple but maybe disenchanting to someone else: It’s in the equalizers transfer curve and (almost) nothing else. That equalizer transfer curve determines the actual frequency and phase response and generally speaking, in an analog filter model the frequency response implies the according phase response (and vice versa). In the digital domain this holds not true in general as shown by linear phase filter implementations. Additional effects like the actual transient response or additionally generated harmonics are then the icing on top (if desired) but may appear quite subtle or even negligible if we just look into rather transparent devices.