Well, all loudspeakers regardless of size or construction cause phase errors. This means that not all frequencies leave the speaker at the exact same point in time. This has to do with physics: The fundamental relation between time and frequency is expressed by the so-called Fourier Transform, which explains that corrections in the frequency domain will inevitably alter the phase response – and vice versa. You can’t have both, linear frequency and phase response at the same time, at least not in an analog loudspeaker design.
#Musicproduction: HEDD releases free Lineariser plug-in - addresses monitor phase and harnesses host CPU power for phase-aligned audio #freedownload