crossover speakers

So, I am looking into upgrading my car's mids and highs, and I want to go from just 4 3 way speakers to 4 mids and 4 tweeters. For this, will I need 4 crossovers or can I just use one, also a link to a wiring diagram for the answer would be great! Thanks

Im switching my front stage up to a pair of soundqubed super tweets and a set of pxw 6.5 mids and wanted to know what a good electronic crossoveris to use. Im pretty new to using crossovers so im looking to you guys to give me some insight. I would be using it with a polk pa660 amp. Any help you...

Im changing up my hi's and mid setup to pro audio but I have no idea about crossover points and how to set them or anything. Is it something you set on the headunit or the amp? If anybody on here can plese break down crossover points and what they mean to me I would really appreciate it, thanks...