6V6 Octal socket basing diagram. 1 - * Unconnected in all versions except for the shell connection of the metal 6V6 2 & 7 - Filament / Heater 3 - Anode / Plate 4 - Grid 2 / Screen Grid 5 - Grid 1 / Control Grid 6 - No connection. Pin normally absent 8 - Cathode & Beam-Forming Plates
The 6V6 is a beam-powertetrodevacuum tube. The first of this family of tubes to be introduced was the 6V6G by Ken-Rad Tube & Lamp Corporation in late 1936,[1] with the availability by December of both Ken-Rad and Raytheon 6V6G tubes announced.[2] It is still in use in audio applications, especially electric guitar amplifiers.[3]
Following the introduction in July 1936 of the 6L6, the potential of the scaled down version that became the 6V6 was soon realized. 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.
Although the 6V6 was originally designed especially for use in automobile radios,[4] the clip-in Loctal base7C5,[5] from early 1939, or the lower heater current 12V6GT, both with the identical characteristics to the 6V6, but with the smaller T-9 glass envelope, soon became the tubes of choice for many automotive radios manufacturers. Additionally, the 6V6 had applications in portable battery-operated radios.[6]
The data sheet information supplied by the tube manufacturers' design-centers list the typical operation of an audio output stage for a single 6V6 as producing about 5W of continuous power, and a push-pull-pair about 14W. Amplifier manufacturers soon realized that the tube was capable of being used at ratings above the recommended maximums, and guitar amplifiers with 400V on the plates of a pair of 6V6GTA claim to produce an output power of 20W RMS at 5%THD with 40W Peak Music Power, and with 490V on the plates, as much as 30 W RMS.
History
Different 6V6 tube envelope dimensions1970's "Coin"-based RCA 6V6GTAVarious 6V6's manufactured around the world; from left to right – 6V6GTA by General Electric, 6V6GT JAN National Union (1940s), 6P6S (USSR, 1978) and modern production 6V6GT by Electro-Harmonix.
Following the 6V6G, RMA Release #96 - 09 Nov. 1936, sponsored by Ken-Rad Tube & Lamp Corporation, with the ST 14 shouldered glass envelope, the 6V6 was announced with a metal mantel in January 1937 by Hygrade Sylvania Corporation.[7] The RMA Release #125 – 03 Jan.1938, Sponsored by RCA. for the 6V6 tube has led to some confusion as to the origins of the 6V6. The 6V6G but not the 6V6 is in the RCA manual RC-13 from July 1937, but the 6V6 is to be found in the 1937 tube manuals of other manufacturers, such as Raytheon.
Tube manufacturers were keen to promote the superiority of the metal tube construction that was introduced on April 1, 1935. Large quantities of the 6V6 tube were produced in the following decade, many as military supply JAN tubes. The price of the metal and glass versions were held to closely the same retail price level for the first few years of their production. The introduction of the 6V6GT, RMA Release #201 – 10 July 1939, was sponsored by Hytron Corporation. By 1940, the 6V6G production was largely superseded by this smaller "GT" T-9 glass envelope.[8] On April 17, 1942, the War Production Board ordered radio tube manufacturers to discontinue within seven days the production for civilian use of 349 of the 710 types of radio tubes on the market, amongst these were the 6V6G and 6V6GX. By 1943, the price of the metal version was almost twice that of the GT version, and this proportional difference in price seems to have remained constant, right through to the end of the 1970s. The 6V6GTA – RMA Release #1681 – 2 July 1956, sponsored by Hygrade Sylvania Corporation, has a controlled warm-up period.[9]
The various different NOS (new old stock) tubes of the 6V6 family, depending on manufacturer, model, series, strength and condition, will vary enormously in scarcity and therefore usually in price. The metal NOS 6V6 tube, once costing almost twice the price of its now highly valued glass enveloped counterparts, is now considered to be fairly common, and is usually the cheapest NOS tube available, with many current production tubes costing more than its 60 to 80 year older classic predecessor. In the final years of U.S. production, several of the major manufacturers switched to using the so-called "coin" based GT bulb.
Current use
Now, over eighty-six years after its introduction, and still retaining its original characteristics, the 6V6 has one of the longest active lifetimes of any electronic component, having never been out of production in all this long period of time. Although historically widely used in all manner of electronic goods, many of which are still in service, it is in guitar amplifiers where its use has become archetypal. Not only are there very many existing amplifiers in regular use that rely on the 6V6, with contemporary reproductions of the more iconic models still being made, modern designers are still keen to develop new creations that rely on its use. Generally speaking, 6V6 tubes are sturdy and can be operated beyond their published specifications (the Soviet made 6P6S,[10] and early Chinese 6V6 versions were not as permissive of exceeding design limits, although current production has improved). Because of this, the 6V6 soon proved itself to be suitable for use in consumer-market musical instrument amplifiers, particularly combo-style guitar amps such as the Gibson GA-40, and the Fender Amplifiers; Champ, Princeton, and Deluxe, some of which drive their 6V6s well in excess of the datasheet specified maximum rating. This ongoing demand encourages Chinese, Slovakian and Russian tube factories not only to keep the 6V6 in production to this day, but to further develop the supply.
The 6V6 Family and equivalents
6V6G – Glass "Shouldered Tube" ST envelope.
6V6GX – Glass "Shouldered Tube" ST envelope, Ceramic Base.
6V6 – Metal jacketed envelope. The metal envelope of 6V6 is connected to pin 1 of the base, and was normally used as a ground. Pin 1 of the other members of the 6V6 family of tubes are usually not internally connected, although some may have the gray RF shield connected.
6V6GT – smaller "Glass Tube" T-9 envelope.
6V6GTA – with a controlled warm-up period.
6V6GTY – a GT with a low loss micanol brown base.
6V6GTX = HY6V6GTX – a GT "Bantam" selected for high gain, with a ceramic base, 15W plate dissipation rating, produced for a limited period around 1941 by Hytron.
5871 – Ruggedized 6V6GT for operation under severe vibrations found in aircraft and similar applications. Radio Valve Co. of Canada Ltd., 1954: RMA #859A.
5992 – Premium, ruggedized 6V6GT with heater current raised to 600mA. Bendix and GE known manufacturers.
7408 – 6V6GT with additional zero-bias characteristics.
6V6S – A modern production, large plated tube, heater current 500mA, with a higher plate and screen voltage rating. Made by JJ Electronic.
6V6GT(A)(B)-STR – Modern production valve, STR signifying "Special Test Requirement." Claiming to be heavy duty, suitable for high plate voltage.
Military specification 6V6 tubes and their equivalents
British Ministry Of Supply valves for the Military & other governmental agencies have a CV number (CV = common valve). Old stores reference numbers with the prefix ZA are also sometimes used. Supplied by Mullard & Brimar.
CV509 = ZA5306 – 6V6G
CV510 – 6V6
CV511 – 6V6GT & 6V6GTY
The British GPO also used their own VT (Valve - Thermionic) numbering system
VT196 = CV509 = 6V6G – General Post Office (GPO)
Swedish Military supplier Bofors, had tubes made by Standard Radiofabrik (SRF) at the Ulvsunda plant in Stockholm.
5S2D - Premium, ruggedized 6V6GT with triple micas, low loss micanol brown base.
Other tubes cited as being equivalent
6P6S (6П6С in Cyrillic.) Also 6П2 - 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, the USSR adopted its own system of designations.
6P11S (6П11С in Cyrillic.) = 6П6С-Y2 - Military consignment, ruggedized 6P6S. OTK tested. Higher Voltage ratings.
1515 - Premium version of the 6P6S (6П6С).
6P6P - Chinese version of the 6V6GT made by Shuguang, but now obsolete, different from Shuguang's current production 6V6GT.
3106 – East German production 6V6GT from OSW (Oberspreewerk Berlin, later HF, then WF with 6П6С & 6V6 marking). Open, split-plate design.
6AY5 – East German production 6V6GT
VT227 = 7184 – Cited equivalent, made by Ken-Rad, inadequate documentation, no RMA registration.
WT-210-00-82 – Cited equivalent, inadequate documentation, no RMA registration.
WTT-123 – Cited equivalent, inadequate documentation, no RMA registration.
6V6HD – NOT a 6V6, but relabeled Sovtek 6L6GA / 6P3S.
Similar tubes
Derivatives of 6V6: 6P6S, 6P1P (USSR), 6L31 (Tesla)
These tubes have very similar characteristics to the 6V6, but differ either in the heater rating, or use a different socket and pin-out
5V6GT - Same as the 6V6GT, but with different heater ratings - 4.7V, 0.6A, controlled 11 sec. warm-up time.
12V6GT - Same as the 6V6GT, but with different heater ratings - 12.6V, 0.225A, suitable for automotive receiver applications.
7C5 - Clip-in Loctal B8G base, T-9 Bulb. Raytheon - 1939 RMA #162. Other version of this tube are 7C5-TV,2C48,2C50,N148,CV885
7C5LT = CV886 - Same as the 7C5, except with a small wafer Octalox base 8-pin T-9 Bulb. RCA – 1940 RMA #234.
14C5 - Same as 7C5 but with 12.6V Heater.
6BW6 = CV2136 - British-made miniature-tube 12W equivalent of the 6V6, 9-pin base B9A.
CV4043 - British-made miniature-tube 13.5W equivalent of the 6BW6, 9-pin base B9A.
6AQ5 - slightly lower specifications to the 6V6GT, miniature glass envelope, 7-pin base B7G. Other equivalents of this tube are the CV1862,EL90,6005,6095,6669,6928,BPM 04,CK-6005,M8249,N727,6L31
12AQ5 - Same as the 6AQ5, but with different heater ratings.
6P1P (6П1П in Cyrillic.) - 9-pin B9A Noval base Soviet version, not identical characteristics, but very close
6973 - US-version, 9 pin Noval base tube, higher plate voltage ratings, intended for high fidelity output applications.
6CM6 - 9 pin Noval base tube, equivalent type primarily intended for vertical deflection amplifiers in television receivers.
12CM6 - Same as the 6CM6, but with different heater ratings.
12AB5 - 9 pin Noval base tube with 12V heater, suitable for automotive receiver applications. Equivalent to the 7061
The pentodeEL84/6BQ5 - 9 pin Noval base tube, that although different enough from the 6V6 not to justify rating it as an equivalent, because of its popularity and ready availability, plus having a close-enough similarity to make it possible, if bias is altered, adapters have been developed commercially to allow an amplifier designed for 6V6 use to accept the noval-based EL84 tube. Likewise, the inverse adapter is also available.
A vacuum tube, electron tube, valve, or tube is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied.
Pro Electron or EECA is the European type designation and registration system for active components.
6SN7 is a dual triode vacuum tube with an eight-pin octal base. It provides a medium gain. The 6SN7 is basically two 6J5 triodes in one envelope.
KT66 is the designator for a beam power tube introduced by Marconi-Osram Valve Co. Ltd. (M-OV) of Britain in 1937 and marketed for application as a power amplifier for audio frequencies and driver for radio frequencies. The KT66 is a beam tetrode that utilizes partially collimated electron beams to form a low potential space charge region between the anode and screen grid to return anode secondary emission electrons to the anode and offers significant performance improvements over comparable power pentodes. In the 21st century, the KT66 is manufactured and used in some high fidelity audio amplifiers and musical instrument amplifiers.
Tube sockets are electrical sockets into which vacuum tubes can be plugged, holding them in place and providing terminals, which can be soldered into the circuit, for each of the pins. Sockets are designed to allow tubes to be inserted in only one orientation. They were used in most tube electronic equipment to allow easy removal and replacement. When tube equipment was common, retailers such as drug stores had vacuum tube testers, and sold replacement tubes. Some Nixie tubes were also designed to use sockets.
6L6 is the designator for a beam power tube introduced by Radio Corporation of America in April 1936 and marketed for application as a power amplifier for audio frequencies. The 6L6 is a beam tetrode that utilizes formation of a low potential space charge region between the anode and screen grid to return anode secondary emission electrons to the anode and offers significant performance improvements over power pentodes. The 6L6 was the first successful beam power tube marketed. In the 21st century, variants of the 6L6 are manufactured and used in some high fidelity audio amplifiers and musical instrument amplifiers.
A beam tetrode, sometimes called a beam power tube, is a type of vacuum tube or thermionic valve that has two grids and forms the electron stream from the cathode into multiple partially collimated beams to produce a low potential space charge region between the anode and screen grid to return anode secondary emission electrons to the anode when the anode potential is less than that of the screen grid. Beam tetrodes are usually used for power amplification, from audio frequency to radio frequency. The beam tetrode produces greater output power than a triode or pentode with the same anode supply voltage. The first beam tetrode marketed was the Marconi N40, introduced in 1935. Beam tetrodes manufactured and used in the 21st century include the 4CX250B, KT66 and variants of the 6L6.
The EL34 is a thermionic vacuum tube of the power pentode type. The EL34 was introduced in 1955 by Mullard, who were owned by Philips. The EL34 has an octal base and is found mainly in the final output stages of audio amplification circuits; it was also designed to be suitable as a series regulator by virtue of its high permissible voltage between heater and cathode and other parameters. The American RETMA tube designation number for this tube is 6CA7. The USSR analog was 6P27S.
The EL84 is a vacuum tube of the power pentode type. It is used in the power-output-stages of audio-amplifiers, most commonly now in guitar amplifiers, but originally in radios. The EL84 is smaller and more sensitive than the octal 6V6 that was widely used around the world until the 1960s. An interchangeable North American type is the 6BQ5.
The Radio Electronics Television Manufacturers' Association was formed in 1953, as a result of mergers with other trade standards organisations, such as the RMA. It was principally responsible for the standardised nomenclature for American vacuum tubes - however the standard itself had already been in use for a long time before 1953; for example, the 6L6 was introduced in July 1936.
In Europe, the principal method of numbering vacuum tubes was the nomenclature used by the Philips company and its subsidiaries Mullard in the UK, Valvo(de, it) in Germany, Radiotechnique (Miniwatt-Dario brand) in France, and Amperex in the United States, from 1934 on. Adhering manufacturers include AEG (de), CdL (1921, French Mazda brand), CIFTE (fr, Mazda-Belvu brand), EdiSwan (British Mazda brand), Lorenz (de), MBLE(fr, nl), RCA (us), RFT(de, sv) (de), Siemens (de), Telefunken (de), Tesla (cz), Toshiba (ja), Tungsram (hu), and Unitra. This system allocated meaningful codes to tubes based on their function and became the starting point for the Pro Electron naming scheme for active devices.
Vacuum tubes produced in the former Soviet Union and in present-day Russia carry their own unique designations. Some confusion has been created in "translating" these designations, as they use Cyrillic rather than Latin characters.
The GU-50 is a power pentode vacuum tube intended for 50 watt operation as a linear RF amplifier on frequencies up to 120 MHz. It is, in fact, a Soviet-produced copy of the Telefunken LS-50 power pentode, possibly reverse-engineered from German (Wehrmacht) military radios captured during World War II, or based on documentation, machines and materials captured as a trophy. It is one of the more unusual types of tube because of its non-standard 8-pin base and a metal "cap" with a plastic "handle" on top of the envelope - which is meant to ease extracting the tube from its socket. One stock Russian-produced socket includes a rugged die-cast metal cage-like enclosure for the tube with spring-loaded locking lid.. Another stock Russian-produced socket is stamped of light aluminium sheet metal, without a lid on top.
The 6P1P is a Soviet-made miniature 9-pin beam tetrode vacuum tube with ratings similar to the 6AQ5, EL90 and the 6V6. Because of a different pinout than an 6AQ5/EL90, it cannot be used as a plug-in replacement for these types; however, it will work in the same circuit with component values unchanged. Its maximum plate/screen voltage and dissipation ratings are actually slightly higher than a 6AQ5. A ruggedized/extended ratings version of the tube is designated 6P1P-EV, roughly equivalent to the 6AQ5W. A Chinese-manufactured version of the tube also exists, labeled 6P1.
A valve audio amplifier (UK) or vacuum tube audio amplifier (US) is a valve amplifier used for sound reinforcement, sound recording and reproduction.
A double diode triode is a type of electronic vacuum tube once widely used in radio receivers. The tube has a triode for amplification, along with two diodes, one typically for use as a detector and the other as a rectifier for automatic gain control, in one envelope. In practice the two diodes usually share a common cathode. Multiple tube sections in one envelope minimized the number of tubes required in a radio or other apparatus.
The KT88 is a beam tetrode/kinkless tetrode vacuum tube for audio amplification.
A magic eye tube or tuning indicator, in technical literature called an electron-ray indicator tube, is a vacuum tube which gives a visual indication of the amplitude of an electronic signal, such as an audio output, radio-frequency signal strength, or other functions. The magic eye is a specific type of such a tube with a circular display similar to the EM34 illustrated. Its first broad application was as a tuning indicator in radio receivers, to give an indication of the relative strength of the received radio signal, to show when a radio station was properly tuned in.
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