Thought this may be an interesting article to post. Its called "High Quality Use of Motorola's Piezo Driver" by Mike Klasco. I found it on the internet, it talks about a number of things to consider when implementing motorola/CTS piezo drivers in a system such as sensitivity, driver to horn matching, piezo crossover, piezo bandwidth, principles behind piezo's and all the other important considerations about piezos. I think people have asked a number of things this article goes through before, so I'll post the links here. Page 1
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The website I got those links from is http://users.tpg.com.au/users/gradds/piezos.htm. On that page also is freq response curves of a number of Motorola piezo's which may be useful to somebody now or in the future.