High pass means that only high frequency signals will pass to be amplified. So in most amps high pass means midrange and tweeters. So if you have 2 amps, one for mids/tweets, and another for subs, you want to set your high pass at 80 to 100 hz on the voice amp. The reason for this is so your voice speakers do not play very low bass notes which could damage them. And in setting them at 80 to 100 hz, you can hear better detail and play them a bit louder.i still trying to learn how to set crossover settings on amp