6V6

6V6 is a beam-power pentode, similar to its predecessor the 6L6. While the 6L6 was an excellent tube, it was not really suitable for use in home consumer electronic devices because its output, especially in a push-pull pair, was so high. With the introduction of the lower-powered 6V6 the beam-power pentode because a usable technology for the home, and began to see common use as the audio output stage of radios and other electronic home entertainment devices where standard power pentodes such as the 6F6 had previously held sway. The 6V6 provided less distortion and required less bias voltage than the 6F6, while still offering higher output in both single-ended and push-pull configurations.

The 6V6 was introduced in both metal and shouldered glass tubes. RCA was promoting the superiority of its metal tube designs in the second half of the 1930s, and this tube, having been introduced during that period, was produced in large quantities in this format. Other tube manufacturers also produced the 6V6 in glass tubes, which were commonly found in radios not made by RCA. By 1940 the 6V6 was mostly being produced in a smaller "GT" glass envelope, and later the 6V6GTA was introduced which had a controlled warm-up period. Also similar is 6AQ5, which has similar specifications but in a miniature glass shell, and the 7408.

These tubes are sturdy and can be run beyond their published specifications. Because of this, the 6V6 became very popular for use in instrument_amplifiers. This market allows Slovak and Russian tube factories to keep the 6V6 in production to this day.

References:

* Stokes, John, 70 YEARS OF RADIO TUBES AND VALVES, Vestal Press, NY, 1982