Simple d.i.y. Low-Pass Filter for Interfacing PMT Amplifier to PC Sound Card (Used with Free “Pulse Recorder and Analyser” Software MCA) – diy Physics Blog
circuit design - Standard ways to make a variable low pass filter - Electrical Engineering Stack Exchange
Low Pass Filter kit
Low pass filter | DIY Elektor Vocoder
Passive Filter Circuits : 4 Steps - Instructables
Simple low pass filter for Hi-Fi speakers
Low Pass Filter Circuit for Subwoofer | Homemade Circuit Projects
100W 12V 3.5MHz-30MHz HF Low Pass Filter High LPF Kit For DIY/Assembled part | eBay
Pure Subwoofer Front Plate Low Pass Filter High Level Input Diy Pre Tone Balanced Input / Output Board - Switch Caps - AliExpress