The times I smoked the piezos... the PA was not running very loud. I think it was inaudible frequencies being picked up, perhaps something RF. Also, there is a huge Datacom tower with a gazillion microwave dishes nearby.

And the driver actually had a melted spot. Interestingly, it seemed to be the internal 22 ohm resistor that actually burned.

The drivers you describe with three screws, these all roll in at 3.5 khz. The larger drivers used on the KSN1165a, KSN1025a, and KSN1142a all roll in at 1800hz.

What are the actual spls you measure with the Motorolas? I have seen widely differing SPL's for the same drivers. For example, I have seen the 1025 listed as low as 90 db/wt/mt (I suppose they mean 2.83v) to a high of 94 db.

In actuality, they seem louder than this. What is your take?