The KT90 is a

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 ...

used in audio applications. Typically, it is used in hi-fi or electric

guitar amplifier A guitar amplifier (or amp) is an electronic device or system that strengthens the electrical signal from a pickup on an electric guitar, bass guitar, or acoustic guitar so that it can produce sound through one or more loudspeakers, which a ...

applications. KT90 was developed by Elektronska Industrija Niš (Ei). KT90 is designed by Blagomir Bukumira,a leading engineer at Ei

Features

The KT90, or in full, "Kinkless Tetrode 90", is a beam power tetrode and features the same octal socket as its smaller variant, the

KT88 The KT88 is a beam tetrode/kinkless tetrode (hence "KT") 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 ...

. It may therefore be used as a substitute, given appropriate re-biasing when used in push-pull configuration. The KT90 is currently manufactured by

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 ...

, who claim that, despite its different construction, it possesses similar sound characteristics to the

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 ...

valve. Semi-formal research has been conducted by U.K. supplier Watford Valves who have published a test report. (This research is described here as "semi-formal" because it consists primarily of listening evaluations which may be subjective, rather than electrical analyses of performance parameters in either numerical or graphical form.)

References

Vacuum tubes Guitar amplification tubes {{Electronics-stub