How efficient are piezo's in terms of % electrical energy converted to acoustic enegery? I know most high eff drivers range 1% to 4 or 5%. But a piezo has MUCH less current with such a high impedance... and they produce very similar acoustice output 92 - 96db vs 96 - 101 db.I don't know what kind of impedances piezos present, I've heard 50 ohms but I've also heard 1kohms, course it depends on frequency (piezo's are similar to a lossy Cap).
Anyone ever calculate it?, I'd imagine it's in the 50% and up range.. ?