Short for Vacuum Tube, a device used to drive amplifiers until the advent of transistors. A tube works like a flood gate, except with heat. A small heater in the base warms up, while a gate like mechanism opens and closes depending on the input signal. As heat goes through the "gate", it is turned into electrical energy. Tube slots must be biased, which determines the voltages seen by the tube. Only guitar amps still use tubes (as well as some bass amps, mic preamps, and other pro audio devices.)

Though a true discussion of tubes is enough to fill a large book, let alone a short definition, but here are some more common types of tubes.

Preamp: American name (European name) Other name
12AX7 (ECC83) 7025
12AT7
12AY7

Rectifier
5U4 (GZ32)
GT5Y3 (GZ30)

Power Amp
6L6GC
6V6GC
EL84
EL34
KT66
6550

Pertaining to the action of inserting ones penis into a banking vacuum tube which gives a sensation of a close encounter of the third kind.

Facetious term for a vacuum tube. The term is a parody of "MOSFET" (Metal Oxide Semiconductor Field Effect Transistor), and is used jovially by vacuum tube enthusiasts.

See also: hollow state

OK, I just want to clear up the previous definition for an Electron Tube (the type used in guitar amps and high-end audio applications). The fella before me said tubes convert heat into electricity, this just goes to show that a little knowledge is a dangerous thing. Tubes do have a heater element, but this is seperate from any signal processing the tube performs. Tubes have anywhere from 3 to 5 elemets inside, not including the heater. The first is called a Plate, this is a metal plate with a given DC voltage applied to it, usually 200 to 400 volts. Another part is called the Cathode, this is connected to ground, sometimes through a resistor or capacitor network. The voltage "wants" to flow from the plate to the cathode, but between them is a "grid." The grid is connected to the input signal and as the signal changes from a positive charge to a negative charge (all musical signals are AC current, oscillating between + and -)it allows more or less of the plate voltage to flow to the cathode, resulting in a large voltage swing on the plate in time with the input signal: the amplified signal. The other elements go between the grid and the plate and serve to make the tube more efficient, these "screens" as well as the grid can be biased, that is, they have a fixed voltage applied to them to more carefully control how much current flows through the tube.
There is a heater element in the tube as well, very similar to a light bulb filament, but this only warms up the other com...

The term FUBES is the plural of fube. A fube's a replacement for a vacuum tube, using FET technology. If you plugged in a fube for a tube, the circuit might work better, but usually not. The fube was invented by engineers at National Semiconductor Corp in the 1960s, but never made any business or profit.

To convert alternating current to direct current by means of a semiconductive material or a vacuum tube.

A negative voltage applied to the grid of a vacuum tube in order to assist the alteration of the flow of electrons from the cathode to the plate.