I used drivers from the M80, 1x tweet, 1x 5.25 Mid, 1x6.5 woof and used a program called Xover 3 to design the crossover. I stuck close to the size of a M22 and also the crossover points Ian uses. Bear in mind I have never done any frequency response test or anything like that yet but they sound good to me,i use them mostly for 2 channel though they are on my surround sound receiver in my bedroom. I did it mostly because I already had the drivers, but also gave me a project to do in the shop. It was more expensive than if I had bought them already made but it was fun.