Bob Savage":25gz91kw said:
glip22":25gz91kw said:
This is what I was bringing in to the thread. Audio and guitar is a small part of the sum.
Any idea where one might find facts? I'm interested in knowing more but most of what I'm finding via searches are only statements about the broad use of vacuum tubes without backing.
From Wikipedia:
Niche applications
Vacuum tubes are much less susceptible than corresponding solid-state components to transient overvoltages, such as mains voltage surges or lightning, or the electromagnetic pulse effect of nuclear explosions. This property kept them in use for certain military applications long after more practical and less expensive solid-state technology were available for the same applications.[2]
Vacuum tubes are still practical alternatives to solid state in generating high power at radio frequencies in applications such as industrial radio frequency heating, particle accelerators, and broadcast transmitters. This is particularly true at microwave frequencies where such devices as the klystron and traveling-wave tube provide amplification at power levels unattainable using current semiconductor devices. The household microwave oven uses a magnetron tube to efficiently generate hundreds of watts of microwave power.
Audiophiles
Enough people prefer tube sound to make tube amplifiers commercially viable in three areas: musical instrument (guitar) amplifiers, devices used in recording studios, and audiophile equipment.[28][29][30] The power output stages of audio amplifiers using tubes include transformers to match the speaker impedance to the higher impedance level of the tube circuit; the use of transformers introduces frequency-dependent phase shifts which limit the amount of negative feedback which can be applied before inducing instability. Solid state power amplifiers, on the other hand, are direct-coupled and apply a high degree of linearisation by negative feedback.
The output transformer will affect the amplifier's tone (amplitude at different frequencies) in response to the speaker's impedance, and will affect the character of the amplifier's distortion as it approaches maximum power—the use of less feedback than in a semiconductor amplifier produces more distortion products, but they are characteristic of a gradual change, rather than a sudden onset of saturation as happens with large amounts of feedback. There are companies which specialize in high-priced audio amplifiers using tube technology to serve this market. Beyond the amplifier's output stage, more controversial claims[31] are made in favor of tubes used in signal amplification stages and even for using tubes as power supply rectifiers. Professional systems such as music recording studios and public address systems[citation needed] rarely employ tubes in microphone preamplifiers or other applications.
Vacuum fluorescent display
A modern display technology using a variation of cathode ray tube is often used in videocassette recorders, DVD players and recorders, microwave oven control panels, and automotive dashboards. Rather than raster scanning these vacuum fluorescent displays (VFD) switch control grids and anode voltages on and off to display discrete characters, for instance. The VFD uses phosphor-coated anodes as in other display cathode ray tubes. Because the filaments are in view, they must be operated at temperatures where the filament does not glow visibly. This is possible using more recent cathode technology, and these tubes also operate with quite low anode voltages (often less than 50 volts) unlike cathode ray tubes. Often found in automotive applications, their high brightness allows reading the display in bright daylight. VFD tubes are flat and rectangular, as well as relatively thin.
Typical VFD phosphors emit a broad spectrum of greenish-white light, permitting use of color filters, though different phosphors can give other colors even within the same display. The design of these tubes provides a bright glow despite the low energy of the incident electrons. This is because the distance between the cathode and anode is relatively small. (This technology is distinct from fluorescent lighting, which uses a discharge tube.)
Those are the few I could find Bob with a little searching, I am sure there are more.
