.
If you don't want to believe me, Ck out the mini-piezo line array in the old Community CSX-70 S2. A box I once successfully did a hip hop show for 2000 people with. (On top of a dozen 18" subs crossed at about 100hz) Not quite as loud as I wanted but "Got R Done". These facts were established about 20 yrs ago. You might call Bruce Howse over at Community and explain to him how ignorant he is about acoustic coupling.
Good Luck w/ That.
Just because you think you did a "successful" show does mean that it was good. With hip hop as long as you have plenty of subs-they are happy.
"Got-r-done" just means you got paid.
Many (if not most) loudspeakers are built for a price point to be competitive. Very often piezos are used to "increase driver count", which does nothing for sound quality. The fewer drivers the better.
If you actually talked to Bruce, you would realize that at the time of that cabinet-those were pretty much a "bottom of the line" product for Community.
Just because they were used does not mean they were great. Many times it is just a matter of getting more HF cheaply-not better HF.
The only cabinet I am familiar with in which a piezo was used successfully was the Dalquist DQ10. The piezo (standard round variety) was high passed around 17Khz (give or take).
It worked-for those that could hear that high.
The only "high quality" cabinet (that I am aware of) that used piezos was the early Meyer MSL3. But later cabinets did not use them.
Most serious uses of the Northwest sound dual 15" 2" 6 (or so) piezos would take the piezos out of service because they did more damage to the sound than what they added.
Maybe there are some good quality products that used them-but I am drawing a blank on that right now.