12AT7
Encyclopedia
Triode
A triode is an electronic amplification device having three active electrodes. The term most commonly applies to a vacuum tube with three elements: the filament or cathode, the grid, and the plate or anode. The triode vacuum tube was the first electronic amplification device...
vacuum tube
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
popular in guitar amplifiers. It belongs to a large family of dual triode
Triode
A triode is an electronic amplification device having three active electrodes. The term most commonly applies to a vacuum tube with three elements: the filament or cathode, the grid, and the plate or anode. The triode vacuum tube was the first electronic amplification device...
vacuum tubes which share the same pinout (EIA 9A) and of which 12AX7
12AX7
12AX7 is a miniature dual triode vacuum tube with high voltage gain. It was developed around 1946 by RCA engineers in Harrison, New Jersey, under developmental number A-4522. It was released for public sale under the 12AX7 identifier on September 15, 1947. The 12AX7 was originally intended as...
is the most prolific type.
Compared to the 12AX7, the 12AT7 has somewhat lower voltage gain, but higher transconductance
Transconductance
Transconductance, also known as mutual conductance, is a property of certain electronic components. Conductance is the reciprocal of resistance; transconductance, meanwhile, is the ratio of the current change at the output port to the voltage change at the input port. It is written as gm...
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
FM broadcasting
FM broadcasting is a broadcasting technology pioneered by Edwin Howard Armstrong which uses frequency modulation to provide high-fidelity sound over broadcast radio. The term "FM band" describes the "frequency band in which FM is used for broadcasting"...
tuners, as an oscillator/frequency converter, but it has also found wide use in audio as a driver and phase-inverter in vacuum tube Push-pull amplifier circuits.
The tube has a center tapped filament so it can be used in either 6.3V 300mA or 12.6V 150mA heater circuits.
12AT7 is also known in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
under its Mullard-Philips tube designation
Mullard-Philips tube designation
In Europe, the principal method of numbering vacuum tubes was the nomenclature developed and used by Mullard in the UK and applied Europe-wide thanks to their parentage by Philips who had subsidiaries in Germany and France , plus the support of Telefunken, from 1934...
of ECC81.
Current production of 12AT7 takes place in Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
(Electro-Harmonix
Electro-Harmonix
Electro-Harmonix is a New York-based company that makes high-end electronic audio processors. The company was founded by Mike Matthews in 1968. They are most famous for a series of popular guitar effects pedals introduced in the 1970s and 1990s....
brand), Slovakia
Slovakia
The Slovak Republic is a landlocked state in Central Europe. It has a population of over five million and an area of about . Slovakia is bordered by the Czech Republic and Austria to the west, Poland to the north, Ukraine to the east and Hungary to the south...
, and China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
.
12AT7 has an amplification factor of 60.
See also
- 12AU712AU712AU7 is a miniature nine-pin medium-gain dual triode vacuum tube. It belongs to a large family of dual triode vacuum tubes which share the same pinout . 12AU7 is also known in Europe under its Mullard-Philips tube designation ECC82...
- 12AX712AX712AX7 is a miniature dual triode vacuum tube with high voltage gain. It was developed around 1946 by RCA engineers in Harrison, New Jersey, under developmental number A-4522. It was released for public sale under the 12AX7 identifier on September 15, 1947. The 12AX7 was originally intended as...
- Several tube datasheets