Quote Originally Posted by Old Guy View Post
Piezos actually come on much earlier than 4K. I tend to put them past an L-pad, and cap them off anywhere from 7-10K. Does cut he efficiency, so I use stacked vertical arrays. Trimming the flanges to close couple the horns can be useful.

Current builder of Motorola designs...

Pulsar Developments Ltd - Piezo Tweeter Application Note
Great article. Thanks for posting that OG.

And thanks for the measurements Marty. I enjoy the geeky stuff!