Last night I broke in a pair of Hi-Vi M6a's after having measured the resonance and it was much higher than the spec sheet. I broke them in for about 3 hours each and today the resonant frequency is still too high. I have tried two methods, both doing about the same thing. I measured for a peak in the voltage drop accross the woofer with a volt meter and then measured the frequency this occured at. I also hooked it up to a FFT analyzer and plotted Voltage vs. Freq. Both resulted in the same answer. For reference I am getting the value "58 Hz" when the spec sheet says 46 Hz. Any help is appeciated.