[Dr. Sivana]

Some special-purpose tubes are constructed with particular gases in the envelope. For instance, voltage-regulator tubes contain various inert gases such as argon, helium or neon, which will ionize at predictable voltages.

Perhaps the term vacuum tube is used loosely, but I know when I was smashing my dad's old TV tubes in the 1st grade classroom metal waste basket, they were releasing SOME kind of gas. I don't know what the school would do if some seven year old did that today. I received a mild rebuke.

[babygene]

“For instance, voltage-regulator tubes contain various inert gases such as argon, helium or neon, which will ionize at predictable voltages.”

There used to be voltage regulator tubes 50 years ago... They were not vacuum tubes though. And they weren’t used in TVs though. Except for antiques, the only vacuum tube we use today as consumers are the magnetron in your microwave oven.

There are a few exceptions to this, for instance some audio buffs think tube amplifiers sound better. They still use traveling wave tubes but most of that has switched over to semiconductors. Some radio transmitters still use them.

[Moltke]

“Some special purpose tubes” - rare and neither audio amplifier tubes nor “vacuum” tubes. And what you experienced was more likely implosion, not explosion.

The typical amplifier triode has a heated cathode - the glow you see and which emits a stream of thermionic electrons - a plate (anode), and inbetween a grid which “regulates” the amount of electrons which reach the plate. A small (music) signal is applied to the grid which controls the (larger) cathode-to-plate current - bingo! amplification! (To drive a loudspeaker usually a transformer is used to convert the high-voltage/low-current signal of the tube to a low-voltage/high-current signal able to drive the speaker.) The presence of *any* gases in the tube would inhibit the flow of electrons from the cathode to the plate and you’d be looking for a replacement. Well, that’s the basic principle.