Two vacuum tubes occupying an 8-pin octal plug-in module. This packaging constitutes an operational amplifier (op-amp) with standard differential inputs and single-ended output. The Philbrick K2 series were the first ever op-amps to enjoy wide success. They were widely used in analog computers and in industrial control systems. [Text by Donor.]
Date
ca 1955
Manufacturer
George A. Philbrick Researches, Inc.
Place Manufactured
U.S.
Identifying Numbers
Model number
GAP/R Model K2-XA
Other number
12AX7A, 7025
Vacuum tube model #s for the right socket, printed on model # label
Other number
6BR8A, 6CL8A
Vacuum tube model #s for the left socket, printed on model # label
