Passive crossovers are designed to work with a driver that has a specific ohm rating (impedance). You have to match the impedance of the blown //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif tweeters to the new ones. You would be surprised how many tweeters on component sets aren't the standard 4 ohms.
If the JL tweeters are 4 ohm and the Cadence were 8ohm (or vice versa), the resulting crossover frequency on the passive will be way different. Just make sure that they are the same ohm rating. If you look at the specs for your tweeters, the information should be there, usually listed as "Re".