I’d guesstimate Infinity employed 2nd order crossovers on the woofer and tweeter and based on the smooth impedance plot below, also incorporated a zobel network or two. It is obvious some good thought ...

The speakers in this case were run full-range with no bass ... within the 15 degree window comes from closely-spaced drivers and well-chosen crossover points. Infinity P363 On-Axis Frequency Response ...

Like all of the new Reference speakers, they incorporate Infinity’s Ceramic Metal Matrix ... The subs come in ported cabinets, and offer controls for crossover, level, and a selectable low ...

Because an anodized-metal woofer, for instance, is stronger than paper or polypropylene woofers typically found in budget speakers, Infinity says the Primus 150 is less susceptible to resonance ...