Not sure If I can add much to this discussion but active crossovers would have been more expensive at the time. The system was already expensive when you add the amp and other requirements. I own two sets of the RS1B woofer towers and the servo controller. These parts are getting old and my servo now has a low level hum that it didn't have before. I now use an active crossover without the servo system and get very satisfactory results. The RS1B was a great system but after listening to the Infinity Emits and Emims for the last 4 decades I have moved on.
Why are the Infinity IRS, Reference 1b, Beta ect speakers passive on the mids and highs?
I would like to know why all of the classic Infinity's and most other brands use passive crossovers for the mid to high transition? I don't think it was for cost and that level. Is passive better? Has anyone compared both to know which is better?