The goal of this design is low-distortion. This means operating drivers within their pistonic range. This range can be determined by rule-of-thumb of 1/2 wavelength of drivers' diameter.
20-300Hz: Eminence Alpha 15"
300-1500Hz: Vifa P13WH
1500-20kHz: tbd (Vifa DX25, XT25, or DX27)
Actively crossed and tri-amped.
Follow this design tread at DIYAudio.
This design had reached a plateau of performance when trying to equalize the midrange from 300Hz and above. Large baffle caused undesirable peak and dip which resulted in rough midrange. Baffle size should be no more than 2x cone diameter for smooth response. Refer to S7 for the final design to fix this issue.