The original diaphragms were not working when I purchased the Model 15. I put Radian 1228-8 diaphragms in to get them going. The bi-flex 412c woofers are very efficient and over powered the 32b horns . The factory crossover runs the woofer full out. EarlK helped and guided me to add to the crossover to "Tame the Bi-flex". I have been listening to them since. The original "Lite" 23744 diaphragms have now been repaired. Time for a comparison . The graph says it all. The originals are now installed.