A type of speaker distribution system where transformers are used at the output of an amplifier and at each speaker in order to provide a constant voltage of, in this case, 70.7 volts that can be tapped by multiple speakers. These lines can be run great distances with less loss and can have many speakers on them as compared to typical high current speaker lines. These types of systems are generally employed in situations where an amplified signal must be distributed over vast areas without a need for very high SPL (see WFTD archive “Sound Pressure Level“) in any one area. This is typically the type of P.A. system you will see in schools, churches, business offices, and commercial facilities like malls and shopping centers.