Below about 80 Hz, humans become progressively worse at locating where a sound comes from. By around 40–60 Hz, it is difficult to pinpoint the source. That doesn't mean it's impossible, because harmonics, vibrations, reflections, and rattling objects often give away the location. The bigger issue is distance. Deep bass doesn't travel "miles away" from a home-sized speaker. While low frequencies are absorbed less than high frequencies, sound pressure still drops rapidly with distance. To produce bass that's clearly audible several kilometres away would require an enormous amount of acoustic power—think concert or industrial-scale systems, not a 2,000–6,000 baht home subwoofer. When buying a subwoofer: Maximum SPL (Sound Pressure Level) is far more important than the wattage printed on the box. Frequency response tells you how low it can play (e.g. 25–120 Hz). Driver size (12", 15", 18") generally matters more for deep bass than amplifier wattage alone. Cabinet design (ported, horn-loaded, bandpass) has a huge effect on output. Ignore exaggerated "PMPO" watt ratings. Look for RMS power and measured SPL. A 15-inch professional PA sub can produce far more bass than a cheap 18-inch home-theatre sub, despite similar advertised wattage. If your goal is for people not to know where the bass is coming from, one high-quality sub crossed over below about 80 Hz can make localization difficult, but it won't be inaudible from miles away.
