The Model 256, known as the Dual Control Voltage Adder, is two completely independednt Control Voltage processors behind one panel. Each half of the 256 functions as a 4-channel, attenuverting voltage mixer with 2 outputs and a master voltage offset, ranging from 0V-15V. Use the 256 to assimilate and manipulate all the varying types of Control Voltage in your system. With two CV mixers in a one space, you are sure to have enough mixing firepower for many system expansions to come. The Model 256 is essential to every DON B Oriented 4U System.