Originally Posted by
jerv
Mostly right. Though all components react with each others (and with the inductance in the driver's voice coil), the 1041 series LCR makes a shallow notch filter (Q=1.2), centered at about 5200 Hz. The C1011 and the parallell LR 1021 takes care of high pass crossover and dampens down the 800Hz-2kHz range. Don't use that crossover if you intend to use a supertweeter. It attenuates the 2445 much more than what is needed with a tweeter.
What you need to do, is to attenuate the 800-3500 Hz range. This can be accomplished with the combination of a notch and a shallow high-pass filter. This is my passive crossover for the 2445J on the 2360 horn, intended for crossovers at about 600 and 8000 Hz. The 2360 is a constant-directivity horn, but the Iwata (as far as I know) isn't. The 2445 on the Iwata should (in theory, at least) need less compensation than on the 2360. My guess is that the same filter topolygy can be used on the Iwatha horn, but components values may vary.