This depends entirely on your equipment--the overload margins of each item (at both their inputs and their outputs), and where the filtering could be applied in the circuit. A very strong disturbance at low frequencies, such as from wind, could cause overload distortion which you wouldn't be able to equalize out.
For example, some condenser microphones when struck by moderate wind might not be overloaded themselves--but then their signals could overload the inputs of your preamp. In that case, an in-line filter just before the inputs of the preamp could save the recording, while later filtering or equalization would be useless. (Also, using pads rather than filters might allow you to find the best filtering choice in post-production.) But if the microphones themselves are overloading due to the disturbance, a filter or pad at the input of the preamp would be too "late" to help.
Does that way of thinking about things help you make sense of the situation?
About reversing the effect of a filter: It's possible in theory, but in practice it's often best to compromise. If the filter was 12 dB/octave below 80 Hz, try restoring about half of that loss first (and maybe only down to 40 Hz--not all the way to 20) to see whether you can be satisfied that way. If you correct for the filter completely, you'll add a lot of low-frequency noise along with the music. Also, any thumps or bumps that you picked up would get amplified to a degree that might cost you a woofer or an amplifier fuse. So go easy on this approach until/unless you're sure that it's safe and that it's what you really want sonically.
--best regards
Topic: 80Hz High Pas Filter Question? (Read 3953 times)