EL34
Encyclopedia
The EL34 is a thermionic valve or vacuum tube
of the power pentode
type. It has an international octal
base (indicated by the '3' in the part number) and is found mainly in the final output stages of audio
amplification circuits and was 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. Russian analog is 6P27S (Cyrillic: 6п27C )
, the EL34 has a heater voltage of 6.3V. According to the data sheets found in old vacuum tube reference manuals, a pair of EL34s with 800V plate voltage can produce 90 watts output in Class AB1
in push-pull configuration. However, this configuration is rarely found. One application of this type was in "Australian Sound" public address amplifiers commonly used in government schools in Australia in the 1950s, using four EL34s for ~200 watts. More commonly found is a pair of EL34s running Class AB1 in push-pull
around 375-450V plate voltage and producing 50 watts output (if fixed bias is used), while a quad of EL34s running Class AB1
in push-pull
typically run anywhere from 425-500V plate voltage and produces 100 watts output. This configuration is typically found in guitar amplifiers, especially Marshalls and is quite hard on the valves.
The EL34 is a pentode, while the 6L6, which delivers a similar range of power output, is a beam tetrode
which RCA
referred to as a beam power tube. Although power pentodes and beam tetrodes have some differences in their principles of operation (the beam plates of the beam tetrode or fifth electrode (3rd grid) of the pentode, both serving to hinder the return of unabsorbed electrons from the anode (or plate) to the 4th electrode (2nd grid)) and have some internal construction differences, they are functionally closely equivalent. Unlike the 6L6
, (EIA base 7AC) the EL34 has its grid 3 connection brought out to a separate Pin (Pin 1) (EIA base 8ET) and its heater draws 1.5 Amps compared to the 0.9 Amp heater in the 6L6. However, Sylvania (and possibly GE) marketed a tube as 6CA7 which was not only in a markedly different 'fat boy' envelope, but used a beam forming plate much like a 6L6. Examining the mica spacer on the top of the tube will confirm the lack of a suppressor grid. Although these tubes have similar (but not identical) characteristics, they are made very differently.
The EL34 was introduced in 1953 by Mullard
and its parent company Philips
and, although no longer made by them, is manufactured by JJ Electronic, Shuguang, Svetlana and Reflector
(Sovtek
, Electro-Harmonix
EI Serbia / Yugoslavia and some brands), amongst others. Some firms make a related tube called an E34L which is rated to require a higher grid bias
voltage, but which may be interchangeable in some equipment.
Stereo 70 and the Leak
TL25(mono) and Stereo 60, and is also widely used in high-end guitar amplifiers because it is characterized by greater distortion
(considered desirable in this application) at lower power than other octal tubes such as 6L6
, KT88
or 6550. The EL34 is found in many British guitar amps and is associated with the "British Tone" (Marshall
) as compared to the 6L6 which is generally associated with the "American Tone" (Fender/Mesa Boogie
).
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...
of the power pentode
Pentode
A pentode is an electronic device having five active electrodes. The term most commonly applies to a three-grid vacuum tube , which was invented by the Dutchman Bernhard D.H. Tellegen in 1926...
type. It has an international octal
Tube socket
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 plugged in in only one orientation...
base (indicated by the '3' in the part number) and is found mainly in the final output stages of audio
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
amplification circuits and was 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
RETMA tube designation
The Radio Electronics Television Manufacturers' Association was formed in 1953, as a result of mergers with other trade standards organisations.It was principally responsible for the standardised nomenclature for American vacuum tubes....
number for this tube is 6CA7. Russian analog is 6P27S (Cyrillic: 6п27C )
Specifications
In common with all 'E' prefix tubes, using the Mullard-Philips tube designationMullard-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...
, the EL34 has a heater voltage of 6.3V. According to the data sheets found in old vacuum tube reference manuals, a pair of EL34s with 800V plate voltage can produce 90 watts output in Class AB1
Electronic amplifier
An electronic amplifier is a device for increasing the power of a signal.It does this by taking energy from a power supply and controlling the output to match the input signal shape but with a larger amplitude...
in push-pull configuration. However, this configuration is rarely found. One application of this type was in "Australian Sound" public address amplifiers commonly used in government schools in Australia in the 1950s, using four EL34s for ~200 watts. More commonly found is a pair of EL34s running Class AB1 in push-pull
Electronic amplifier
An electronic amplifier is a device for increasing the power of a signal.It does this by taking energy from a power supply and controlling the output to match the input signal shape but with a larger amplitude...
around 375-450V plate voltage and producing 50 watts output (if fixed bias is used), while a quad of EL34s running Class AB1
Electronic amplifier
An electronic amplifier is a device for increasing the power of a signal.It does this by taking energy from a power supply and controlling the output to match the input signal shape but with a larger amplitude...
in push-pull
Electronic amplifier
An electronic amplifier is a device for increasing the power of a signal.It does this by taking energy from a power supply and controlling the output to match the input signal shape but with a larger amplitude...
typically run anywhere from 425-500V plate voltage and produces 100 watts output. This configuration is typically found in guitar amplifiers, especially Marshalls and is quite hard on the valves.
The EL34 is a pentode, while the 6L6, which delivers a similar range of power output, is a beam tetrode
Beam tetrode
A beam tetrode is a type of vacuum tube specially designed to produce greater output power than a similar pentode...
which RCA
RCA
RCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. The RCA trademark is currently owned by the French conglomerate Technicolor SA through RCA Trademark Management S.A., a company owned by Technicolor...
referred to as a beam power tube. Although power pentodes and beam tetrodes have some differences in their principles of operation (the beam plates of the beam tetrode or fifth electrode (3rd grid) of the pentode, both serving to hinder the return of unabsorbed electrons from the anode (or plate) to the 4th electrode (2nd grid)) and have some internal construction differences, they are functionally closely equivalent. Unlike the 6L6
6L6
6L6 is the designator for a vacuum tube introduced by Radio Corporation of America in July 1936. At the time Philips had already developed and patented power pentode designs, which were fast replacing power triodes due to their greater efficiency...
, (EIA base 7AC) the EL34 has its grid 3 connection brought out to a separate Pin (Pin 1) (EIA base 8ET) and its heater draws 1.5 Amps compared to the 0.9 Amp heater in the 6L6. However, Sylvania (and possibly GE) marketed a tube as 6CA7 which was not only in a markedly different 'fat boy' envelope, but used a beam forming plate much like a 6L6. Examining the mica spacer on the top of the tube will confirm the lack of a suppressor grid. Although these tubes have similar (but not identical) characteristics, they are made very differently.
Mullard
Mullard Limited was a British manufacturer of electronic components. The Mullard Radio Valve Co. Ltd. of Southfields, London, was founded in 1920 by Captain Stanley R. Mullard, who had previously designed valves for the Admiralty before becoming managing director of the Z Electric Lamp Co. The...
and its parent company Philips
Philips
Koninklijke Philips Electronics N.V. , more commonly known as Philips, is a multinational Dutch electronics company....
and, although no longer made by them, is manufactured by JJ Electronic, Shuguang, Svetlana and Reflector
Reflector
-Science:* Reflector, a device that causes reflection * Reflector , used to control lighting contrast* Reflecting telescope* Reflector , the part of an antenna that reflects radio waves...
(Sovtek
Sovtek
Sovtek is a brand of vacuum tube owned by Mike Matthews's New Sensor Corporation and manufactured in Saratov, Russia. They are often used in guitar amplification and include the popular variants of the 12AX7, EL84, EL34, and 6L6 models...
, 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....
EI Serbia / Yugoslavia and some brands), amongst others. Some firms make a related tube called an E34L which is rated to require a higher grid bias
Grid bias
Grid bias is a DC voltage applied to electron tubes with three electrodes or more, such as triodes. The control grid of these devices is used to control the electron flow from the heated cathode to the positively charged anode...
voltage, but which may be interchangeable in some equipment.
Application
The EL34 was widely used in higher-powered audio amplifiers of the 1960s and 1970s, such as the very popular DynacoDynaco
Founded by David Hafler and Ed Laurent in Philadelphia, Pennsylvania in 1955, Dynaco was an American hi-fi audio system manufacturer popular in the 1960s and 1970s for its wide range of affordable, yet high quality audio components..-Early company history:...
Stereo 70 and the Leak
LEAK
LEAK is the brand name for high-fidelity audio equipment made by H. J. Leak & Co. Ltd, of London, England. The company was founded in 1934 by Harold Joseph Leak and was sold to the Rank Organisation in January 1969. During the 1950s and 60s, the company produced high-quality amplifiers, radio...
TL25(mono) and Stereo 60, and is also widely used in high-end guitar amplifiers because it is characterized by greater distortion
Distortion
A distortion is the alteration of the original shape of an object, image, sound, waveform or other form of information or representation. Distortion is usually unwanted, and often many methods are employed to minimize it in practice...
(considered desirable in this application) at lower power than other octal tubes such as 6L6
6L6
6L6 is the designator for a vacuum tube introduced by Radio Corporation of America in July 1936. At the time Philips had already developed and patented power pentode designs, which were fast replacing power triodes due to their greater efficiency...
, KT88
KT88
The KT88 is a beam tetrode/kinkless tetrode vacuum tube for audio amplification.- Features :The KT88 fits a standard eight-pin octal socket and has similar pinout and applications as the 6L6 and EL34. Specifically designed for audio amplification, the KT88 has similar ratings to the American 6550...
or 6550. The EL34 is found in many British guitar amps and is associated with the "British Tone" (Marshall
Marshall Amplification
Marshall Amplification is a British company, founded by drummer Jim Marshall, that designs and manufactures music amplifiers, brands personal headphones/earphones , and, after acquiring Natal Drums, drums and bongos. Marshall amplifiers, and specifically their guitar amplifiers, are among the most...
) as compared to the 6L6 which is generally associated with the "American Tone" (Fender/Mesa Boogie
Mesa Boogie
Mesa/Boogie is a company in Petaluma, California that makes amplifiers for guitars and basses. It has been in operation since 1969....
).
See also
- EL84EL84The EL84 is a vacuum tube of the power pentode type. It has a 9 pin Noval base and is found mainly in the final output stages of amplification circuits, most commonly now in guitar amplifiers, but originally in radios and many other devices of the pre-transistor era.It was developed to eliminate...
- PentodePentodeA pentode is an electronic device having five active electrodes. The term most commonly applies to a three-grid vacuum tube , which was invented by the Dutchman Bernhard D.H. Tellegen in 1926...
- 6V66V6The 6V6 is a beam-power tetrode, introduced by Radio Corporation of America RCA United States in late 1937, and still in use in niche applications.Similar to its predecessor the 6L6, the 6V6 was far more widely used...
- 6L66L66L6 is the designator for a vacuum tube introduced by Radio Corporation of America in July 1936. At the time Philips had already developed and patented power pentode designs, which were fast replacing power triodes due to their greater efficiency...
- 5881
- KT63
- KT66KT66The KT66 is a beam tetrode/kinkless tetrode vacuum tube for audio amplification.KT66 is the designator for a vacuum tube introduced by Marconi-Osram Valve Co. Ltd. of Britain in 1937....
- KT88KT88The KT88 is a beam tetrode/kinkless tetrode vacuum tube for audio amplification.- Features :The KT88 fits a standard eight-pin octal socket and has similar pinout and applications as the 6L6 and EL34. Specifically designed for audio amplification, the KT88 has similar ratings to the American 6550...
- 6550
- Beam tetrodeBeam tetrodeA beam tetrode is a type of vacuum tube specially designed to produce greater output power than a similar pentode...
- Tube data archive
- List of vacuum tubes