KSUB-112A / KSUB-115A are sub-bass system with the built-in amplifier, use the electronics crossover and professional power amplifier design improved the bass extending, the exact power handling match and the perfect acoustics design to build the purity and natural sound to karaoke vocal speaker. Control the bass volume (The crossover adjustable from 40Hz to 250Hz could be adjusted). auto protection circuitry system.