Beginner Question About Replacing Tubes

[Victor]

So the preamp tube in my amp finally died, and I’m trying to replace it, but I have a question. I’ve heard that you should never touch your tubes, because the oils from your fingers could cause a temperature difference on the surface of the glass and cause the tube to shatter when it’s warmed up. I can’t find too much information about the subject, and I’ve found at least one site that calls this a myth, so my question is if this is really true? Does anyone have any first-hand experience on this matter? If this is true, is there a way to clean the tube after you’ve already touched it? Does mild dish detergent do the trick?

[Enzo]

This is a myth. it comes from people confusing projector bulb safety with glass tubes. Projector bulbs - we should refer to them as lamps really - and high power lamps such as used in stage lights and spotlights, operate at very high temperatures, and if you handle them, they will indeed bubble up and fail.

Vacuum tubes like we use in amplifiers are NOWHERE near that hot. They are cool enough you CAN touch them. Touch a projector lamp and you will lose your skin.

And of the vacuum tubes, the preamp tubes in particular run a lot cooler than the power tubes.

Touch them all you want. Only reason I'd clean them is to make an amp look spiffy after I repair it. You could even stick a piece of masking tape on the tube and it won't hurt it.

It is totally not necesssary to clean tubes, but to shine them up, they are glass after all, a squirt of WIndex ON A RAG, and then wipe them will work. On older tubes this might remove some of the lettering, so one more reason to leave them alone. Don't squirt fluid on the tube, since a drop might linger and get into the works of the socket. Water and electricity don't mix, especially at several hundred volts. Use a damp rag.

When they are uncomfortably hot, I use a rag or a glove. But that protects ME, not the tube.

If you wirk with hot tubes a lot, one of these things is useful:

[Enzo]

Sorry. That is a Tube Glove from New Sensor. It is like a rubber oven mitt for tubes. Big end for 6L6 size and small end for preamp tube size.

[Victor]

Thanks for the response.