|This article relies largely or entirely upon a single source. (November 2013)|
Similar to its predecessor, the 6L6, the 6V6 was far more widely used; the 6L6 produced more output power than required by general-use consumer electronic devices of the time, with corresponding power and circuit requirements. The lower-powered 6V6 was better suited for average home use, and became common in the audio output stages of "farmhouse" table-top radios, where power pentodes such as the 6F6 had previously been used. The 6V6 required less heater power and produced less distortion than the 6F6, while yielding higher output in both single-ended and push-pull configurations. Additionally, the 6V6 had applications in the automotive and portable radio market.
In an audio output stage, a single 6V6 can be used to produce about 5W (continuous) power, and a push-pull pair about 14W, with the higher output requiring a larger, more expensive output transformer with grain-oriented core laminations for better efficiency.
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.
Generally speaking, 6V6 tubes are sturdy and can be operated beyond their published specifications (the 6P6S, which has poor tolerance for out-of-spec operation versus most American and West European-made 6V6 variants, is an exception). Because of this, the 6V6 became very popular for use in consumer-market musical instrument amplifiers, particularly combo-style guitar amps such as the Fender Champ, the Gibson GA-40, and the Fender Princeton Reverb, and Fender Deluxe Reverb amps, which run a push-pull pair of 6V6s at 410V-plus on the plates. This market allows Chinese, Slovakian and Russian tube factories to keep the 6V6 in production to this day. Because of the relative similarity in voltage and characteristics between the 6V6 and the popular EL84/6BQ5 power pentode tube, several electronics and musical instrument companies have developed adapters to allow an amplifier with 6V6 octal sockets to accept the miniature noval pinned EL84 tube. However, no reverse adapter, that is to allow a mini-noval EL84 socket to accept a 6V6, has been developed.
A similar tube is the 6AQ5, which has similar specifications to the 6V6GT, but in a miniature glass shell with a 7-pin base (this base being known in the UK as B7G), the 7408, and the Soviet-produced 6P1P, which is essentially the same as 6AQ5, but has a 9-pin base. Also with a 9-pin base (UK B9A) was the 6BW6, an exact miniature-tube equivalent of the 6V6. The 6973 was a US version with higher plate voltage ratings intended for high fidelity output applications. The 6CM6 is a 9-pin miniature equivalent type primarily intended for vertical deflection amplifiers in television receivers. The 12AB5 is another 9-pin miniature variant with a 12V heater, suitable for automotive radio applications.
In the Soviet Union a version of the 6V6GT was produced since the late 1940s which appears to be a close copy of the 1940s Sylvania-issue 6V6GT – initially under its American designation (in both Latin and Cyrillic lettering), but later, after USSR had adopted its own system of designations, the tube was being marked 6P6S (6П6С in Cyrillic.)
- Stokes, John. 70 Years of Radio Tubes and Valves. NY: Vestal Press, 1982