linguistic:voice_change, quality:corruption
Cathode-ray tubes

The cathode-ray tube (CRT) is a vacuum tube used particularly for display purposes. Although there are still many televisions and computer monitors using cathode-ray tubes, they are rapidly being replaced by flat panel displays whose quality has greatly improved even as their prices drop. This is also true of digital oscilloscopes (based on internal computers and analog-to-digital converters), although traditional analog scopes (dependent upon CRTs) continue to be produced, are economical, and preferred by many technicians. At one time many radios used " magic eye tubes ", a specialized sort of CRT used in place of a meter movement to indicate signal strength or input level in a tape recorder. A modern indicator device, the vacuum fluorescent display (VFD) is also a sort of cathode-ray tube.

The X-ray tube is a type of cathode-ray tube that generates X-rays when high voltage electrons hit the anode.

Gyrotrons or vacuum masers, used to generate high-power millimeter band waves, are magnetic vacuum tubes in which a small relativistic effect, due to the high voltage, is used for bunching the electrons. Gyrotrons can generate very high powers (hundreds of kilowatts)., Free-electron lasers, used to generate high-power coherent light and even X-rays, are highly relativistic vacuum tubes driven by high-energy particle accelerators. Thus, these are sorts of cathode-ray tubes.