Load Impedance as a Function of Power Input in 70-Volt, 100-Volt, and 25-Volt Distribution Systems
Distributed loudspeaker systems often make use of 70-volt or 100-volt distribution methods. In a 70-volt system, the full power of the amplifier, whatever it might be, is always available at 70 volts rms. By means of the appropriate distribution transformers, a given number of watts may be drawn from the line by a given loudspeaker. When the sum of electrical watts taken from the line equals the power rating of the amplifier, the system is fully loaded. The benefit here is that the design engineer does not have to make laborious system load impedance calculations for each loudspeaker placed across the line, but merely has to keep track of the number of watts drawn.