Don,
I have a question for you - on the clone of the N-1500 crossover that you built for me, I want to adjust this for 8 ohm drivers. Would that imply to double C1 and halve L1? This would result in 0.75 mH value for L1 and 28 uF for C1... I don't have a circuit simulator that will let me do that for a series filter, but was going to try to prototype it this weekend.