Crossover definition

I'm not too technically knowledgeable but I'll go out on a limb here a little bit.

I don't think that Butterworth is a crossover. Rather it's a filter used in the crossover. It prevents the frequency response from getting too wavy around the crossover point. Since almost all crossovers use Butterworth filters, they are often called Butterworth crossovers.

Perhaps someone more knowledgeable might be able to add to (or contradict) this.

I came across this link while trying to educate myself on this topic, keeping in mind that I'm not too technically knowledgeable. It contains other links to basic information on crossovers. Perhaps. along with other posts, it will help in getting you down along the road to the information which you seek