Built to Thrill: Alto Professional's Black Series is a full line of elite speaker systems, each designed to exacting standards with premium, purpose-matched components and immense built-in power. Black Series speakers have been designed with one goal in mind: satisfying the ears of your audience with the most gratifying and immersive sound experience theyve ever had. Both Black Series subwoofersthe Black18S and Black15Shas been crafted to thunder with finely tuned sound in a virtually limitless variety of applications: from touring rigs to permanent installations and everything in between. And with 2400 watts of peak power each one comes equipped to thrill. The Peak of Power: Beyond their differences in transducer size, each Black Series sub contains the same 2400 watts of earth-shaking, low-end power and specifically crafted, purpose-matched components for maximum efficiency. Designed and tuned in the USA, the Black18S and Black15S both come with stereo inputs and outputs, adjustable level and polarity controls and precision-engineered cabinets, which have been designed to deliver maximum sonic impact.