Crossover Research: Series vs Parallel, first order second order, third order

[rwnano]

https://tubecad.com/2017/11/blog0402.htm
Please see this link!

Juicy bits:

About 30 years ago, I knew an electrical engineer with a PHD from Stanford, whose doctoral dissertation was on electronic filters; he had retired from Hewlett Packard and was devoting his efforts to loudspeaker crossovers. He told me that after years of analysis and experiment no crossover—no matter how elaborate and complex—could beat the simple, first-order series crossover.

[Quoting Heyser] The frequency description of a signal and the time description of that signal are tangled up with each other in a very fundamental way. The parameter that we call "time" and the parameter that we call "frequency" are not independent of each other...And no amount of Band-Aid engineering with running transforms or things called instantaneous frequency is going to change that fact.

edit: cool overview of first order, second order/linkwitz-riley, and third order/butterworth with series and parallel variations and value calculations and ratios