Bad to replace tubes while amp is running?

[Whitneydrew35]

I am working on my AO29 amp and was wondering if it’s bad to replace tubes and take them in and out while the organ is running. Haven’t done it yet because I’m not sure if it’s harmful but the tubes I’m working with are the 6AU6’s and 12AU7 tubes
Thanks !

[sirmiken]

Yes, power the electronics down before removing or inserting tube.

[Tim_at_Jonas]

I've pulled and replaced tubes in operating amps and preamps (of all types) hundreds of times, and have never had an issue. It can make a heck of a noise though, so there's that. And don't get burned.

[KC9UDX]

Same here. Remember there's two ways to get burnt!

Be extra careful with grid caps. In fact, do those with the power off unless you really know what you're doing. Some of them are plate caps!

But as for the single-ended ones, not really a big deal. Have you ever changed an incandescent light bulb that was powered on? It's just a monode tube. (Actually a gas monode.)