In the screen below you see the same system as above but this time with a shorted tweeter. The green (upper) plot again shows the normal impedance response of this system. The yellow (lower) plot shows the system with a shorted tweeter. The system with the shorted tweeter appears to have a suspiciously low impedance above 4 kHz or so but when compared to the normal response (green) it is easy to see there is a problem.