Winding the coils

Since the exact values for the inductors I needed weren't available, I decided to buy some 16 gauge magnet wire and wind my own. After looking at a number of U-tube videos, I built a simple winding jig:  It wasn't quite as easy as the video made it look but eventually I had four coils. One was about 20 turns light because I ran out of wire. I think I was short changed on the spool I bough on Amazon - I won't be  buying from TechFix again. The online calculator seemed way off for two of them. Instead of 2.25 mH, the large coil was 1.6mH; not even close. So it was back to the shed with a hack saw and some nails. The addition of a steel core (should be iron but steel was the best I could improvise) boosted the impedance to 6.8mH. That meant I could unwind more than half the turns on both coils. The two home made cores are on the right - on the 2.25mH coil you can just see the nails under the blue insulating tape.  On the right is the network schematic. 

While I stated with a set of theoretical values, must succumbed to trial-and-error fine tuning in Speaker Workshop as I matched the network to the particular measured characteristics of the mounted drivers.

My wife's comment when I showed her the finished crossover was "it looks like something a 5-year old would have made". I was pleased; that something that looks so rough produces such nice results evoked the same feeling I had when I first visited the 8th floor of the Blackett laboratory. In display cabinets in the elevator lobby were devices that had been instrumental in a number of major experimental discoveries in particle physics. They too looked like "something a 5-year old would have made". It doesn't need to look good to work well, something Prof. Ken Bignell also taught me