NPD - Broughton Low + High Pass Filter. Does a great job of cleaning up muddy low end and hissy high end frequencies I don't want. Just the creamy middle! : r/BassGuitar
RE/Q - DUAL FUNCTION EQUALIZATION PEDAL - Genzler Amplification
Broughton (HPF) High Pass Filter Pedal | Reverb
Low + High Pass Filter | Broughton Audio
Death By Audio Evil Filter Hyper Resonant Multi Mode Filter/Fuzz Pedal Black | Guitar Center
Pigtronix Introduces the Resotron Analog Filter Pedal – No Treble
Used Broughton High Pass Filter Pedal | Musician's Friend