Electro-Voice MTL-4A is a low-frequency loudspeaker system designed for high-level concert sound reinforcement in touring sound and permanent installation applications. Its vented-box design comprises four DL18MT woofers facing into a manifold chamber, resulting in increased acoustic loading and low-frequency efficiency. The MTL-4A is engineered to deliver optimum performance when used with the dedicated MTX-4A electronic crossover/equalizer/time-delay unit, forming the four-way active MT-4A concert-sound loudspeaker system.