I am building some budget speakers for my brother, but these are my first "full range" set that I have ever built. I have never dealt with anything but subs before. My question, if I put a crossover into the speaker system, will it, and if so how much, effect the final impedance? For instance, I see 4 ohm and 8 ohm crossovers, do I have to take these numbers into account when calculating the impedance load? Your help is always appreciated.