Ghxamp Subwoofer Preamplifier Low-pass Filter Board Home Car Subwoofer Speaker Preamp Use Dual Channel Single Power 9-32v - Speaker Accessories - AliExpress
Subwoofer Preamp Board,HIFI Low Pass Filter
Low pass filter for subwoofer
SUB-1Rev.2 Active Subwoofer Low Pass Filter High Quality Freq.50Hz~235Hz + 45Hz Bass Boost - Motronix