Axiom Home Page Forums General Discussion Technical Questions Iron Man 2 fluttering

The cabinet itself is an acoustic high-pass filter. But put enough power into it, and you'll still cause significant speaker movement. It's not just that the drivers can't play 20 Hz, the air in the cabinet itself will help to impede cone movement below a certain frequency, offing some protection.

There can easily be content down to 5 Hz or so recorded on digital formats. I have CDs with 5 Hz tones. Without a crossover setting those notes would come out the main speakers.