I'm trying to record owls calls with the AM in the IPX7 case but I'm not getting anything, while I know that they are there calling. Looking at the spectrum it seems that the low frequencies are very weak in my recordings. The case+AM works fine when recording bats. My current assumption is that the case does not play nice with below 1kHz sounds. How do people deal with this problem? Does turning up the gain while filtering high frequency signals do any good, or should I use a different kind of enclosure?