I believe, and may need to be corrected, that piezo tweeters have a very high effective impedance. If so, parallel is the way to go. Go ask in DIYaudio
Connecting Piezo-electric Tweeters
Hello,
I am building a full range speaker cabinet with a Pyle 10" speaker, a mid range horn and four Piezo-electric tweeters. I have a 3-way crossover (with no documentation but clearly labeled connections for Woofer, Midrange and Tweeter outputs.
Should I connect all the tweeters directly to the Tweeter connection individually or should I make the wiring of the four Tweeters in a series/parallel wiring configuration?
Many thanks for your response, Eric.