Rock-Solid Sound from the Bottom, Up The best performances need the best in sound reinforcement at all ends of the sonic spectrum. For tight, punchy low-end look no further than the Alto Professional TS15S powered subwoofer. When added to your full-range speaker setup, the TS15S subwoofer delivers powerful but controlled low-end presence to your PA configuration for a full and complete listening experience for the modern public music space. With a powered subwoofer, any musical performance will take a giant leap into the realm of tonal balance with the perfect blend of hi, mid, and extended low-end frequencies.