passive radiator or bass reflex?! Interesting check it out!!! diy speaker building - YouTube
Passive radiator speaker cabinet with calibration box made by me, I optimized the frequency response of cheap passive radiator bought in aliexpres. Achieve 40 Hz - 16KHz with 3 dollar PR : r/DIY
Building a Small Passive Radiator Subwoofer- by SoundBlab - YouTube
DIY portable bluetooth speaker with heavy bass passive radiators - YouTube