Looking at LR4 networks specifically most diy loudspeaker builders believe the 4th order refers to be the electrical voltage drive from the passive or active crossover. This is incorrect. It’s the final acoustic response of the drivers after the electrical voltage drive is optimised. Obtaining this is beyond the means of most diy loudspeaker builders unfortunately. Manual optimisation is a tedious and time consuming task. Commercial loudspeakers manufacturers use a CAD crossover optimisation engine which can model and accurately predict a final network optimisation.

Peter Larson who worked closely with JBL in the 1990’s to develop CAD design software now owns Loudsoft CAD systems used by loudspeaker manufacturers worldwide. These system start at US$10,000. It is far superior to the LEAP system used previously.

https://loudsoft.com/about-loudsoft/