User requirements for modern modular high-power concert sound reinforcement systems dictate new advances in loudspeaker cabinet design. An elaborate C.A.D. system is set up. The results lead to specific solutions used in prototypes, whose performance is measured and compared to simulations. The complex transference and impedance data are then stored in the C.A.D. system for filter design and optimization. Use and performance of new cabinets in high power sound reinforcement are discussed.