Old thread, I can tell you the crossover is fiendishly complex, if you recap with poly films you need to add 2 ohms of resistance before the cap or things will be bright. The tweeter sucks. A CTS, look on ebay for a Marantz or Jensen oem tweeter, cheapest way to find them, I think PE dropped them. Or find a 87-88ishdb dome tweeter. They play really deep, need to be near a wall. Some nice copper beryllium domes on ALiEx. These are power hungry, about 87db, but do sing once they get rolling. Honestly the best mod for this speaker is a 500hz 2 way x-o and just run one mid as a mid/tweeter. Those mids are from the Model 20 something full range speaker, about 4 light coats of spray polyurethane tames the mid shout and they are FE103 killers.