Determining an original DC from a later DC Series Amplifier:
Original DC amplifiers have a two position toggle switch on the front panel that provides manual switching from Rhythm to Lead. These models also feature a five position rotary switch on the rear panel for manual EQ selection. Later model DC's have a three positon toggle switch on the front panel which is labeled(top down): Rhythm - Lead - Lead/EQ. These models feature a two positon toggle switch on the rear panel for EQ channel assignment.