page_title: Vacuum tube
section_title: Audiophiles
hierarchical_section_title: Vacuum tube / Vacuum tubes in the 21st century / Niche applications / Audiophiles
caption_attribution_description: English: Space-Tech Lab. SE-300B-70W power amplifier , single-ended 70Wrms/ch with 300B
context_page_description: A vacuum tube, an electron tube, valve or tube, is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied.
  The type known as a thermionic tube or thermionic valve uses the phenomenon of thermionic emission of electrons from a hot cathode and is used for a number of fundamental electronic functions such as signal amplification and current rectification. Non-thermionic types, such as a vacuum phototube however, achieve electron emission through the photoelectric effect, and are used for such purposes as the detection of light intensities. In both types, the electrons are accelerated from the cathode to the anode by the electric field in the tube.
  The simplest vacuum tube, the diode, invented in 1904 by John Ambrose Fleming, contains only a heated electron-emitting cathode and an anode. Electrons can only flow in one direction through the device—from the cathode to the anode. Adding one or more control grids within the tube allows the current between the cathode and anode to be controlled by the voltage on the grids.
context_section_description: Enough people prefer tube sound to make tube amplifiers commercially viable in three areas: musical instrument (e.g., guitar) amplifiers, devices used in recording studios, and audiophile equipment.
  Many guitarists prefer using valve amplifiers to solid-state models, often due to the way they tend to distort when overdriven. Any amplifier can only accurately amplify a signal to a certain volume; past this limit, the amplifier will begin to distort the signal. Different circuits will distort the signal in different ways; some guitarists prefer the distortion characteristics of vacuum tubes. Most popular vintage models use vacuum tubes.
caption: 70-watt tube-hybrid audio amplifier selling for US$2,680[50] in 2011, about 10 times the price of a comparable model using transistors.[51]
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