YAMAHA NS-SW500 ตู้ลำโพงซับ 250 วัตต์ 20-160 Hz 25cm (10'') cone 

Advanced Yamaha Active Servo Technology (Advanced YST) is a unique system in which the speaker and amplifier work together to cancel out impedance so the speaker unit has a perfectly linear motion. Advanced YST helps to ensure the highest levels of sound pressure and overall performance.

QD-Bass (Quatre Dispersion Bass) technology uses down-firing drivers with square, pyramid-shaped reflective plates to radiate the sound efficiently in four horizontal directions. The reflective plates negate any effects caused by the floor surface and reduce resonance between sound waves reflected from the floor and the unit.