Cos there is quite a big gap between the bass driver and the tweeter,Ive cut a hole for a 5 1/4 inch midrange driver,

But it is rated at 40w rms,8 ohms,87 db 1w/1m

I know passive crossovers for 300w rms are expensive,but the only
thing that needs the crossover is the midrange,So i know capacitors
for crossovers must be non-polarised,and at least 100v but i don't know what uf value to buy.I've heard between 1uf-10uf is fine for trebles, but is that the same for small midranges. If I got a 6.8uf cap for example would this be enough to stop the damaging bass signals from reaching the midrange driver?

Also Audio Grade Axial Polyproplene caps last longer than standard electrolitic ones.