In 1966 Neumann adapted the "phantom powering" method that had been used for years in certain telephone systems, so that a compatible method of powering would allow tube microphones, solid-state microphones and dynamic microphones all to be connected to the same power supplies. Eventually the "fet 80" series grew to include over a dozen models, some of which are still in production as of 2018—the U 87, U 89, KMR 81, KMR 82 and USM 69. The best-known models from this series were the KM 84 small diaphragm cardioid and the U 87 three-pattern, large diaphragm successor to the U 67.