Western Electric service manual pages covering the 49-A & B amplifiers which shows the original diagram with the 246A input transformer in the circuit with the 700 & 706A apparatus box.
You are visitor no. 496.
Around 1930 ERPI modified the 49 A & B amplifiers to accommodate the 18 db higher output of the new 3-A photoelectric cells used in movie projectors. This modification bypassed the 246-A input transformer and also replaced the two 239-A tubes with the less microphonic 264-A tubes which also drew more filament current. The drawings on this page show the original configuration of the 49 as it was in 1929.
