Accuton C25-6-158 CELL

The THD measurements at voltage levels 2.83 - 4 V were carried out with High Pass Filter "on" (2nd order Buttreworth type, 500 Hz cutoff, HPF2-500)

The THD measurements at voltage level 5.6 V were carried out with High Pass Filter "on" (2nd order Buttreworth type, 800 Hz cutoff, HPF2-800)

The THD measurements at voltage level 8 V were carried out with High Pass Filter "on" (2nd order Buttreworth type, 1200 Hz cutoff, HPF2-1200)

The THD measurements at voltage level 11.2 V were carried out with High Pass Filter "on" (4th order Buttreworth type, 1500 Hz cutoff, HPF4-1500)

I very much like the sounding of C25-6-158 tweeter, but specific for this model (for all exemplars) very strange intrinsic resonance in the frequency range 7 - 9 kHz, which is not seen on frequency response, but clearly evident on THD diagrams and its high retail price (around $400) doesn't allow give it 5*, so, it gets only 4*...

Fortunately, despite the ugly behavior of THD curves in the range 7 - 9 kHz, I can't hear any artifacts and signs of that resonance