The LS1208 “basspipe” subwoofer system. The "basspipe" is a multiple flare horn, connected to an organ like pipe, slowly flaring to the mouth. The bandwidth is narrowed, optimized to a specific range in the lower registers. Outdoor measurements show very smooth, very high output in the 35Hz to 200Hz range. This is the highest efficiency that we have ever seen for a single 18” driver enclosure, especially with a gross volume of only 22 cubic feet.