The polarity is reversed this way on the midhorn/tweeter crossover of six, seven and eight π speakers, which use a single coil (pseudo) first-order filter on the mid driver and a third-order on the tweeter. It is not reversed on the Pro four π, which also uses a single coil on the midwoofer and a third-order on the tweeter. Both have a 1.6kHz crossover, but on the six, seven and eight π speaker, the mid is further from the listener. On the Pro four π, the tweeter is further than the midwoofer.