The KT88 is a

beam tetrode 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 charg ...

/kinkless tetrode (hence "KT")

vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. The type kn ...

for

audio Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum *Digital audio, representation of sound ...

amplification.

Features

The KT88 fits a standard eight-pin

octal The octal numeral system, or oct for short, is the radix, base-8 number system, and uses the Numerical digit, digits 0 to 7. This is to say that 10octal represents eight and 100octal represents sixty-four. However, English, like most languages, ...

socket and has similar

pinout In electronics, a pinout (sometimes written "pin-out") is a cross-reference between the contacts, or ''pins'', of an electrical connector or electronic component, and their functions. "Pinout" now supersedes the term "basing diagram" that was the s ...

and applications as the

6L6 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.J. F. Dreyer Jr."The Beam Power Output Tube" New York: McGraw-Hill, ''Ele ...

and

EL34 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 (indicated by the '3' in the part number) and is found mainly in the final output st ...

. Specifically designed for audio amplification, the KT88 has higher plate power and voltage ratings than the

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

6550 Tung-Sol was an American manufacturer of electronics, mainly lamps and vacuum tubes. History Tung-Sol was founded as Tung-Sol Lamp Works Inc. in Newark, New Jersey in 1907. Their early products were mainly geared towards the automotive market ...

. It is one of the largest tubes in its class and can handle significantly higher plate

voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...

s than similar tubes, up to 800

volts The volt (symbol: V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). It is named after the Italian physicist Alessandro Volta (1745–1827). Defini ...

. A KT88 push-pull pair in class AB1 fixed bias is capable of 100

watt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Wa ...

s of output with 2.5% total harmonic distortion or up to about 50W at low distortion in hi-fi applications. The transmitting tubes TT21 and TT22 have almost identical transfer characteristics to KT88 but a different pinout, and by virtue of their

anode An anode is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, an electrode of the device through which conventional current leaves the device. A common mnemonic is ...

being connected to the top cap have a higher plate voltage rating (1.25

kilovolt The volt (symbol: V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). It is named after the Italian physicist Alessandro Volta (1745–1827). Defini ...

) and a higher power output capability of 200 watts in class AB1 push–pull. The

screen grid A tetrode is a vacuum tube (called ''valve'' in British English) having four active electrodes. The four electrodes in order from the centre are: a thermionic cathode, first and second grids and a plate (called ''anode'' in British English). T ...

is sometimes tied to the anode so that it becomes effectively a

triode A triode is an electronic amplifying vacuum tube (or ''valve'' in British English) consisting of three electrodes inside an evacuated glass envelope: a heated filament or cathode, a grid, and a plate (anode). Developed from Lee De Forest's 19 ...

with a lower maximum power output.

History

The KT88 was introduced by GEC in 1956 as a larger variant of the

KT66 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.Editors "The New Valves" ''W ...

. It was manufactured in the

U.K. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

by the MOV (

Marconi-Osram Valve M-OV (Marconi-Osram Valve Company) was a British manufacturer of thermionic valves (vacuum tubes). It was a subsidiary of the (British) General Electric Company Ltd. The company was founded in 1919, when the valve making interests of GEC (Osra ...

) subsidiary of G.E.C, also labelled as IEC/Mullard, and, in the U.S., Genelex ''Gold Lion''. Kt88 power tubes in traynor yba200 amplifier

As of 2022, KT88 valves are produced by New Sensor Corporation ( Genalex Gold Lion and

Electro-Harmonix Electro-Harmonix (also commonly referred to as EHX) is a New York City-based company that makes electronic audio processors and sells rebranded vacuum tubes. The company was founded by Mike Matthews in 1968. It is best known for a series of gu ...

brands) in Saratov, Russia,

JJ Electronic JJ Electronic, s.r.o is a Slovak electronic component manufacturer, and one of the world's remaining producers of vacuum tubes. It is based in Čadca, in the Kysuce region of Slovakia. Most of its products are audio receiving tubes, mainly used ...

in Čadca, Slovakia and Hengyang Electronics ( Psvane brand) at former Guiguang factory in Foshan, China. NOS examples in good condition are extremely rare. Due to its availability and characteristics, the KT88 is popular in hi-fi production amplifiers. Historically, it has been far more popular with high fidelity stereo manufacturers than

guitar The guitar is a fretted musical instrument that typically has six strings. It is usually held flat against the player's body and played by strumming or plucking the strings with the dominant hand, while simultaneously pressing selected stri ...

amplifier builders, given its characteristics of high-power and low-distortion. Due to these characteristics, it is regularly used to replace 6550 tubes by end users seeking a guitar amplifier tone with less distortion. Some of the amplifiers which shipped with the KT88 power tube include the

Hiwatt Hiwatt is a British company that manufactures amplifiers for electric guitars and electric basses. Starting in the late 1960s, together with Marshall and Vox, Hiwatt contributed to the sonic image popularly termed "British sound". History O ...

Marshall Major The Marshall Major (Model 1967 ) was a bass guitar amplifier made by Marshall. It was introduced in 1967 as the "Marshall 200" (in reference to the power of the amplifier). It had a plexi panel and two inputs in one channel, but in contrast with t ...

, and some

Ampeg Ampeg is a manufacturer best known for its bass amplifiers. Originally established in 1946 in Linden, New Jersey by Everett Hull and Stanley Michaels as "Michael-Hull Electronic Labs," today Ampeg is part of the Yamaha Guitar Group. Although ...

models.

Characteristics

File:Kt88pent.gif, Anode characteristics

References

External links

Reviews of KT88 tubes.

Tube Data Archive, thousands of tube data sheets
{{DEFAULTSORT:Kt88 Vacuum tubes Guitar amplification tubes Audiovisual introductions in 1956

Features

History

Characteristics

See also

References

External links