Editing 6SN7

{{short description|Dual low-frequency, medium-gain octal triode vacuum tube}}
[[Image:Raytheon 6SN7 by Jeff Keyzer.jpg|thumb|6SN7 vacuum tube dual triode made by Raytheon]]
'''6SN7''' is a dual [[triode]] [[vacuum tube]] with an eight-pin [[Tube socket#Octal base|octal base]]. It provides a medium gain (20 dB). The 6SN7 is basically two '''6J5''' triodes in one envelope.

[[Image:EIA-8BD.png|thumb]]

==History==
[[File:6SN7russ.JPG|thumb|Soviet version ''6Н8С'']]

The 6SN7 was originally released in 1939. It was officially registered in 1941 by RCA and Sylvania as the glass-cased '''6SN7GT''', originally listed on page 235 of RCA's 1940 RC-14 Receiving Tube Manual, in the Recently Added section, as: '''6SN7-GT'''. Although the 6S-series tubes are often metal-cased, there was never a ''metal-envelope'' 6SN7 (there being no pin available to connect the metal shield); there were, however, a few glass-envelope tubes with a metal band, such as the '''6SN7A''' developed during World War II - slightly improved in some respects but the metal band was prone to splitting.{{citation needed|date=October 2014}}

Numerous variations on the '''6SN7''' type have been offered over the years, including:
* '''7N7''' (Sylvania 1940, short-lived [[Tube_socket#Loctal|loktal]]-base version),
* '''1633''' (RCA 1941, also for 26-V radios),
* '''12SX7''' (RCA 1946, intended for use in 12-volt aircraft electronics),
* '''5692''' (RCA 1948, a super-premium version - not exactly identical - with guaranteed 10,000-hour lifetime),
* ''' ''6Н8С'' ''' ([[Cyrillic]], Soviet version, {{Circa|1950}}, in Latin letters: '''6N8S''');
* '''6SN7 DDR''', '''6Н8М''', '''E1606''' (='''CV278'''), '''OSW3129''' versions with different/larger glass envelopes;
* '''6042''' (1951, another 1633 type), and
* '''6180''' (1952)
* '''6SN7W''' (1956; a more rugged military version, glass envelope with metal band)<ref>{{cite web|title=6SN7W at the National Valve Museum|url=http://www.r-type.org/exhib/aad0076.htm}}</ref>

The American military designator for the 6SN7GA is '''VT-231'''. The British called it '''CV1988'''. European designations include the 1942 '''ECC32''' (not an exact equivalent), '''13D2''' and '''B65'''.

The 6SN7 has a 6.3 V 600 mA heater/filament. The 12-volt 300 mA filament equivalent is the '''12SN7GT''' or '''12SN7GTA'''. The '''14N7''' is the Loktal version of the 12SN7GT. There was also a comparatively rare 8V '''8SN7''' for 450&nbsp;mA series-string TV sets) and 25 Volt/0.15 Amp heater version: '''25SN7GT'''.

== Related types ==
The 1937 '''6F8G'''<ref>{{cite web|title=6F8G|url=http://www.radiomuseum.org/tubes/tube_6f8g.html|access-date=10 June 2014}}</ref> was also an octal-based double triode with essentially the same characteristics as the 6SN7 (or two 6J5's), but in a 'Coke Bottle' large (Outline ST-12) glass envelope with a different pin arrangement and utilising a top cap connection for the first triode's grid (making pin 1 available for a metal shield).

== 6J5 ==
The '''6J5''', first registered in June 1937,<ref name="6J5">{{cite web|title=6J5|url=http://www.radiomuseum.org/tubes/tube_6j5.html|access-date=10 June 2014}}</ref> and '''6J5GT''' (registered April 1938; British version '''L63''') were octal single triodes with identical characteristics to one half of a 6SN7.   Other equivalents to the 6J5 include: 
* '''VT-94''', '''6C2''', '''6J5M''', '''38565J'''; 
* military versions: '''CV1933''', '''10E/11448''' and '''CV1934'''; 
* [[Loktal]] base version: '''7A4''' (military name: '''CV1770'''), and 
* 12.6 V heater version: '''12J5'''. 
They in turn were successors to the 1935 RCA '''6C5''' and 1938 '''6P5G'''.<ref name="6J5" />

==Successors to the 6SN7 ==
The 1954 '''6CG7'''<ref>{{cite web|title=6CG7|url=http://www.radiomuseum.org/tubes/tube_6cg7.html|access-date=10 June 2014}}</ref> and '''6FQ7''' are electrically equivalent to the 6SN7, with [[Tube socket#Noval base|nine-pin miniature ("Noval")]] base (RCA, 1951), also made as an 8.4V 450mA series string heater type as the '''8CG7'''.

In contrast to what some sources claim, the '''ECC40''' with [[Tube socket#Rimlock base|Rimlock base]] and introduced by Philips in 1948 cannot be considered a successor to the 6SN7<ref>{{cite web|title=ECC40|url=http://www.radiomuseum.org/tubes/tube_ecc40.html|access-date=10 June 2014}}</ref> as the electrical characteristics are too different.

The 1946 miniature [[12AU7]]/'''ECC82''', with similar, but not identical, electrical characteristics to the 6SN7 and ECC32, and a filament usable on either 6.3V or 12.6V supplies, is more widely used than the 6CG7/6FQ7.

== Usage ==
[[File:6SN7 tube by JJ Electronic.jpg|right|thumb|150px|6SN7 by [[JJ Electronic]] ]]
The 6SN7 was used as an audio amplifier in the 1940-1955 period, usually in the driver stages of power amps.  The designer of the famous [[Williamson amplifier]], one of the first true [[high-fidelity]] designs, suggested use of the 6SN7 (or B65) in his 1949 revision since it is similar to the original circuit's '''L63''' (=6J5) British single triodes, four of which were used in each channel of his 1947 circuit.

The 6SN7 was one of the most important components of the first programmable electronic digital computer, the [[ENIAC]], which contained several thousand of the tubes. The [[Semi Automatic Ground Environment|SAGE]] computer systems used hundreds of 5692s as [[Flip-flop (electronics)|flip-flop]]s.

With the advent of television, the 6SN7 was well suited for use as a vertical-deflection amplifier.  As screen sizes became larger, voltage and power headroom became insufficient.  To address this, uprated versions  with higher peak voltage and power ratings were introduced. The '''GE 6SN7GTA''' (GE, 1950) had [[anode]] dissipation uprated to 5.0 watts. The 1954 GE 6SN7GTB also had  controlled heater warmup time, better for [[Series and parallel circuits|series]] heater strings.

The 6SN7 was considered to be obsolete by the 1960s, replaced by the [[12AU7]], and became almost unobtainable. With the introduction of [[semiconductor electronics]], vacuum tubes of all types ceased to be manufactured by the major producers. A small demand for vacuum tubes in [[guitar amplifier]]s and very expensive high-fidelity equipment remained.  As existing stocks ran out, factories in eastern Europe and China started to manufacture the 6SN7, and higher-gain '''6SL7'''.  {{As of|2019}}, 6SN7s and 6SL7s are still manufactured in Russia and by [[JJ Electronic]], and are widely available.<ref>[http://www.hotroxuk.com/electro-harmonix-6sn7eh.html?gclid=EAIaIQobChMImJT64sXp4wIVgrHtCh2BVw45EAQYAiABEgK67vD_BwE Available to buy]</ref>

==See also==
[[File:6SN7 tube - dual triode.jpg|right|thumb|120px|Dual triodes]]

*[[List of vacuum tubes]]
*[[12AT7]]
*[[12AU7]]
*[[12AX7]]

== References ==
{{reflist}}

== External links ==
* [http://tubecollectors.org/ The Tube Collectors Association]
* [https://frank.pocnet.net/sheets/082/6/6SN7.pdf  Datasheet on the 6SN7]
* [[RCA]] Receiving Tube Manual, RC-14, Harrison NJ, 1940
* RCA receiving Tube Manual, RC-29, harrison NJ, 1973
* [[Osram Sylvania|Sylvania]] Technical Manual 14th edition (reprint), 2000
* GE Techni-Talk, Volume 6 number 5, October–November 1954
* [https://frank.pocnet.net/sheets/093/6/6CG7.pdf Datasheet on the 6CG7]
* [https://web.archive.org/web/20081028142502/http://www.joeltunnah.com/JT_TUBELIBRARY.txt] SPICE MODEL
* [http://www.tubemaze.info/tag/6sn7/ Reviews of 6sn7 tubes.]

[[Category:Vacuum tubes]]
[[Category:Guitar amplification tubes]]