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A valve amplifier or tube amplifier is a type of electronic amplifier that uses vacuum tubes to increase the amplitude or power of a signal. Low to medium power valve amplifiers for frequencies below the microwaves were largely replaced by solid state amplifiers in the 1960s and 1970s.
A valve RF amplifier (UK and Aus.) or tube amplifier is a device for electrically amplifying the power of an electrical radio frequency signal. Low to medium power valve amplifiers for frequencies below the microwaves were largely replaced by solid state amplifiers during the 1960s and 1970s, initially for receivers and low power stages of ...
The tube is popular in hi-fi vacuum tube audio as a low-noise line amplifier, driver (especially for tone stacks), and phase-inverter in vacuum tube push–pull amplifier circuits. It was widely used, in special-quality versions such as ECC82 and 5814A, in pre-semiconductor digital computer circuitry.
Circuits designed since then in most cases remain similar to circuits from the valve age, but benefit from advances in ancillary component quality (including capacitors) as well as general progress across the electronics industry which gives designers increasingly powerful insight into circuit operation.
Since the amplifier is usually at the top of the combo, the tubes often hang upside down facing the body of the enclosure. They may be held in with clips. Most modern valve guitar amplifiers use a class AB1 push-pull circuit with a pair of power pentodes or beam tetrodes, 6L6 or EL34 but occasionally KT88 , 6550 , or the lower-power EL84 in ...
12AT7 (also known in Europe by the Mullard–Philips tube designation of ECC81) is a miniature nine-pin medium-gain (60) dual-triode vacuum tube popular in guitar amplifiers. It belongs to a large family of dual triode vacuum tubes which share the same pinout (EIA 9A), including in particular the very commonly used low- mu 12AU7 and high-mu 12AX7 .
A TWTA consists of a traveling-wave tube coupled with its protection circuits (as in klystron) and regulated power supply electronic power conditioner (EPC), which may be supplied and integrated by a different manufacturer. The main difference between most power supplies and those for vacuum tubes is that efficient vacuum tubes have depressed ...
Mullard Circuits for Audio Amplifiers is a famous book by the Technical Services Department of Mullard Ltd, a British valve manufacturing company. First published in 1959 and then reprinted several times it contained a number of designs by Mullard engineers for high quality audio amplifiers, which were to be used by amateur constructors as well as by manufacturers as the basis for many ...