The Alpha 10 is best crossed over at 1.6kHz. Response is great to that point, then falls 15dB at 2kHz. That makes a perfect place to crossover, since the acoustic rolloff adds to the electrical rolloff to make a nice clean break.Above 2kHz, output rises to the nearly the midband SPL and remains high to about 3.5kHz. So if there is no electrical crossover, the horn generates output to 3.5kHz, with a dip at 2kHz.