You can visit my blog for more details: http://maj.pavlin.si/2020/06/09/2-way-audio-crossover/

I designed a simple 2-way passive audio crossover, consisting of 2 power inductors and 2 electrolytic capacitors. This makes for a second-order design or 12 dB/octave. This order is commonly used in passive crossovers as it offers a reasonable balance between complexity and response. Higher order audio filters are harder to design, because components interact with each other.

I calculated the component values based on the Linkwitz–Riley capacitor and inductor ratios. I chose the cutout frequency to be at 4000 Hz. This value was choosen to better protect the tweeter from lower frequencies.