active requires more amplifiers.
passives require a capacitor, and possibly an inductor, and maybe some resistors if the speakers need level-matching.
a single cap gives a "first order" response. basically, the "impedance" of the cap increases as frequency decreases. it effectively starts to block the bass by preventing extra current from flowing. the inductor does something similar, except it is wired in parallel with the speaker. its impedance decreases as frequency decreases. this allows the inductor to steal some of the current that does get through the capacitance, allowing even less to the speaker.
and this can go on in stages -- capacitor in series, inductor in parallel. take this output and put a capacitor in series and so on.
passives require a capacitor, and possibly an inductor, and maybe some resistors if the speakers need level-matching.
a single cap gives a "first order" response. basically, the "impedance" of the cap increases as frequency decreases. it effectively starts to block the bass by preventing extra current from flowing. the inductor does something similar, except it is wired in parallel with the speaker. its impedance decreases as frequency decreases. this allows the inductor to steal some of the current that does get through the capacitance, allowing even less to the speaker.
and this can go on in stages -- capacitor in series, inductor in parallel. take this output and put a capacitor in series and so on.
