Where to get an assembled crossover?

Hi! Looking for an already assembled crossover (2-Way 2nd order 8 Ohms 525 Hz). Eminence used to have the PXB2:500, which was crossed at 500 HZ and would have worked fine, also crossed at 600 HZ would have been a suitable alternative, since it is a hybrid speaker (woofer in a vented enclosure and full range driver in open baffle configuration), but they have discontinued those lower range 2-Way crossovers, and now they start at 800 Hz.

Please, can someone point me to a crossover assembler or a company that might have those low Hz crossovers?