RCF SUB 8006-AS Overview The black SUB 8006-AS Professional Series Active Subwoofer from RCF features two 18” transducers with 4” inside/outside voice coils, designed to deliver a strong low frequency response. This direct radiating, high output, large-format subwoofer system is designed to compliment full-range loudspeakers. Driver mounting maximizes cone area and minimizes frontal area, providing acoustical performance and physical configuration well suited for creating large subwoofer arrays.