Historical Memorabilia from Columbia Square Hollywood, California A 1920's KNX Western Electric studio microphone was used, as shown in the above photo, in the dedication ceremony for the opening of the Columbia Broadcasting System Columbia Square in 1938.  It was mounted on a polished wood base and gifted to the retiring Director of Engineering on his 36th year with KNX/CBS.  The station call letters KNX standout on both front and back of the microphone.  It stands 10" high.Produced by Western Electric and defined as a double button carbon mic with B1 desktop enclosure.It is one of the most recognized microphones of the early days of broadcasting.  The housing is 8 inches high, and 6 inches in diameter.  The 387w element is 3 1/2 inches in diameter, and just under 2 inches deep.  It is heavy for it's size (about 2 1/2 lbs.) and primarily made of nickel-plated cast iron.These microphones required an external DC power supply (batteries), which most microphone setups today don’t supply.   3 wires connected to the mic, 1 for power, 1 for ground and the 3rd to receive the signal.