Thanks for posting the Vandersteen interview.
It inspired me to try once more to tame my TAD 1601s
that reside in sealed 3cuft boxes. It worked, but the numbers
are slightly shocking. 12mH translates to 100Hz, and 25 uF
on 4 Ohm Altec 290’s in 260 Hz horns is 1000 Hz.
But alas, put together they create a smooth midrange transition.
I takes a lot to tame those 15’s first order, and similarly many
midrange drivers I have tried tend to have a rising response
around 500-1000 Hz.
So much for the crossover calculator. Listening, and measuring
a little, has once again brought that First order rightness and pleasure.