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Schematic symbol used in circuit diagrams for a vacuum tube, showing control grid. The control grid is an electrode used in amplifying thermionic valves (vacuum tubes) such as the triode, tetrode and pentode, used to control the flow of electrons from the cathode to the anode (plate) electrode. The control grid usually consists of a cylindrical ...
GR – Rectifier tube; SR – Transmitter tube; VR – Amplifier tube; The third letter specifies the cooling method: L – Forced air; S – Radiation; V – Vapor (the anode is immersed in evaporating water, and the steam is collected, condensed and recycled) W – Water; The first digit (or the first two digits in double tubes) indicates the ...
The 12BV7, 12BY7, 12BY7A, and equivalents were a class of medium-low gain, pentode vacuum tube amplifiers using the Noval socket configuration. Although originally marketed as pentode tubes for use in early television receivers, they found additional uses in audio and radiotelephone equipment. The series shares the EIA 9BF pinout with a number ...
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.
It is common to drive valve power amps directly from such source, using passive volume and input source switching integrated into the amplifier, or with a minimalist "line level" control amplifier which is little more than passive volume and switching, plus a buffer amplifier stage to drive the interconnects.
Vacuum tube equipment used a number of tubes, each with a heater requiring a certain amount of electrical power. In AC/DC equipment, the heaters of all the tubes are connected in series . All the tubes are rated at the same current (typically 100, 150, 300, or 450 mA ) but at different voltages, according to their heating power requirements.
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 ...