7199

The 7199 is a vacuum tube, combining a pentode and triode.^[1] Typically, the pentode was used for the input stage, and the triode as a phase inverter.^[2] The tube was used in a number of American guitar amplifiers; the Gibson Guitar Corporation, for instance, used the 7199 in 1961's Falcon for the reverb circuit.^[3] Ampeg also used the 7199 extensively.^[1] Notable is the Dynaco ST-70 stereo amplifier introduced in 1959 which used a 7199 tube in the driver section of each channel. Over the next decade more than 350,000 of these amplifiers were produced.^[4] American 7199 production ended sometime in the 1980s while the Soviet tube company Sovtek produced one until roughly 2007. As a result the tube is becoming increasingly scarce. Another tube of the same type found in far more plentiful supply is the 6U8A, which is electrically identical, but with a different pinout configuration. The 6U8A can be substituted for a 7199 with a slight modification to the wiring of its tube socket.^[5]

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