Great Upgrade for Ti 2425/2426 JBL 4430/35s
If you have speakers that use JBL 2425 or 2426 horn drivers, you probably know that the diaphragms are titanium, and that the earlier 2421 Alnico drivers had aluminum diaphragms. The AL diaphragms are sought-after, and widely considered to sound smoother, with less distortion, than the Tis. But unfortunately, their surrounds are also AL and over time they fatigue and can fracture. They also handle less power, which is why JBL switched to Ti, following a very embarrassing public fiasco where a bunch of their PS systems failed at the Academy Awards (R), or so I have read.
This situation would leave one with a choice of smoother, but weaker and more expensive (AL), or harsher, but more robust (Ti). Miraculously, though, Radian has stepped in with an AL diaphragm that has a robust Mylar (R) surround, combinging the best of both worlds. I just installed them in my JBL 4430s, with 2425 drivers, and the installation was a basic drop in. (word of warning: Control all ferrous metal fasteners and wires to prevent damage to the diaphragm from magnetic attraction, and replace the gooey foam in the back cap with felt. Also pay careful attention to the order in which the fasteners and terminals are stacked in terms of rubber and metal parts, and maintain the OEM polarity, with green or red indicating positive on the diaphragm).
The DC resistance of the diaphragms is about 3.1 ohms (stock Tis was 4.1) but based on what I;m hearing and the graphs published by Radian, the output seems to be very equivalent. As compared to the Tis, though sound seems smoother and less compressed at high output levels; it really opens up these speakers and smooths them out. And if you call up Radian, as I did, you may be able to speak directly to the engineer who builds these things; he gave me tons of interesting details regarding their construction, and I gather that their team includes ex-JBL and Altec engingeers who continue to build drivers in Orange County, CA, and Radian claims that it it the only remaining US-based driver manufacturer in the world (!).
In sum, I say, there are a remarkable value.