Gentlemen, you cannot used a polarized capacitor in a crossover. Audio signals are alternating current so polarity goes both positive and negative.

The fact that speaker connections are labeled positive and negative is probably what's misleading you. The labeling is so that you get the same phase AC voltage for each speaker - it does not indicate the presence of DC voltage.

If you put a polarized electrolytic, in a crossover it will introduce distortion. If you and crank it up, you'll fry the capacitor.

You can create a non polarized capacitor by wiring two polarized capacitors in series connecting + to +. In this configuration the overall capacitance will be half the rating of the individual capacitors.