The KSLi-GSUB is a purpose-built installation subwoofer designed to enhance the performance of d&b audiotechnik’s KSLi Series loudspeaker systems, specifically complementing the KSLi8 and KSLi12 models. Engineered for fixed installations requiring controlled and accurate low-frequency reinforcement, the KSLi-GSUB provides a cardioid dispersion pattern to minimise unwanted sound radiation behind the enclosure. This results in greater clarity and reduced low-frequency build-up in reverberant spaces, making it ideal for acoustically sensitive venues such as performing arts centres, houses of worship, and corporate auditoriums. The KSLi-GSUB features a robust 2-way active design, housing three 15-inch long excursion neodymium drivers. Two of these drivers face forwards, while the third is rear-facing, each operating within independently tuned bass reflex chambers and powered by separate amplifier channels. This configuration ensures focused bass output with improved directivity and low environmental impact. With a frequency range extending from 36 Hz to 105 Hz, the KSLi-GSUB delivers consistent performance across a wide range of low-frequency content. Constructed from marine-grade plywood and coated with a durable polyurea finish, the enclosure is built to withstand long-term installation conditions. Designed exclusively for ground-stacked deployment, the KSLi-GSUB includes no rigging hardware, further supporting its role in permanent audio installations requiring reliable and controlled low-end reinforcement.