12AT7

12AT7

12AT7

Miniature medium-gain dual triode vacuum tube

12AT7 (also known in Europe by the Mullard–Philips tube designation of ECC81) is a miniature nine-pin medium-gain (60) dual-triode vacuum tube popular in guitar amplifiers. It belongs to a large family of dual triode vacuum tubes which share the same pinout (EIA 9A), including in particular the very commonly used low-mu 12AU7 and high-mu 12AX7.

Old production General Electric "narrow plate" 12AT7 (left) and current production "long plate" Electro-Harmonix 12AT7 (right)

The 12AT7 has somewhat lower voltage gain than the 12AX7, but higher transconductance and plate current, which makes it suitable for high-frequency applications.

Originally the tube was intended for operation in VHF circuits, such as TV sets and FM tuners, as an oscillator/frequency converter, but it also found wide use in audio as a driver and phase-inverter in vacuum tube push–pull amplifier circuits.

This tube is essentially two 6AB4/EC92s in a single envelope. Unlike the situation with the 6C4 and 12AU7, both the 6AB4 and the 12AT7 are described by manufacturer's data sheets as R.F. (Radio Frequency) devices operating up to VHF frequencies.[1]

The tube has a center-tapped filament so it can be used in either 6.3V 300mA or 12.6V 150mA heater circuits.

As of 2012 the 12AT7 was manufactured in Russia (Electro-Harmonix brand), Slovakia (JJ Electronic), and China.

See also

References

  1. [1]
    Tung-sol data sheets for EC92 and 12AT7/ECC81 dated January 1969 and January 1952 respectively
Share this article:

This article uses material from the Wikipedia article 12AT7, and is written by contributors. Text is available under a CC BY-SA 4.0 International License; additional terms may apply. Images, videos and audio are available under their respective licenses.