Esoteric, perhaps, but a little research uncovered this interesting evolution of network topology for JBL's workhorse Sound Reinforcement two-way:
4691B Anybody have a READABLE version? L-Pad attenuation.
SR4725 Attempts to balance drivers, an attenuation switch, lower Xover frequency for 2226H?
SR4725A Fixed attenuation, add Neutrix.
SR4725X Back home again, no attenuation, 1/4" inputs GONE.