what makes vacuum tubes the better choice for some application (most notably an amp for music) over more modern options?
In: Engineering
At least in the area of musical instrument amplification it’s more traditional and aesthetics with a little bit of component properties. People generally refer to tube amps as sounding ‘warmer’ or distorting pleasantly, which is often the case, but it’s less about the tubes and more about the circuit they’re in. It’s possible to make an appreciably similar amplifier with transistors but it’d be as big and bulky as a tube one, except without all the pretty glass tubes to look at.
Outside of music, vacuum tubes have some other uses. The magnetron that makes your microwave function is a vacuum tube. As is the display used in cathode ray televisions (aka CRTs). Vacuum tubes are pretty good at directing and aiming electromagnetic waves, and they still see use in areas where this is desirable.
They arguably aren’t, not any more. Semiconductors are no longer at a power disadvantage, so tubes only really stick around due to personal preference.
Tube amplifiers have a widely-considered pleasing effect when driven near saturation, in exactly the same way that transistor amps don’t. Tubes don’t go into hard clipping instantly, they distort more gradually.
They also look cool.
For radio broadcasts, they may remain in use for some FM high-power applications. Tubes tend to be more rugged and tolerant of bullshit like heat, higher SWR, lightning, or even an EMP, at the cost of burning more energy and having hazardous voltages in the cabinet. AM broadcasters have switched en masse to solid state module-based transmitters due to lower power consumption and smaller rack size, as well as hot swappability of individual drive modules. FM broadcast transmitters are starting to migrate to all-solid state too, but tubes are hangin’ in there even today.
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