Please help diagnose bad new tube

[StormNinjaPenguin]

Hi all,

I finished my stock Crack last week (I love it!) and I bought a tube that's mentioned a lot in the tube rolling thread (Russian 6H13C) and it has an issue: after about 15-30 minutes the tube makes this hollow screeching noise:
imgur.com/a/M54m2Qd (I had to butcher the link because it didn't let me post it, please switch on sound if you open it)

I use open-back headphones and it's really annoying. I also hear the same nature of noise from the left cups of the headphones but it's too quiet to capture on a microphone - still, it's loud enough to be disturbing while listening to music. Also just gently shaking the tube next to my ear, I hear some rattling.

I don't experience any of these with the stock GE tube.

Is there a technical expression to this problem? I don't want to sound total noob when I write to the seller, even though I am a noob. According to some reviews, their customer service can be hard to deal with.

[Paul Birkeland]

It sounds like you got a tube that's a bit noisy.  I'd leave it on overnight and let it cook in to see if it goes away.  Even if the noise subsides a bit, that may be a sign that it could be remedied by running in for an extended period.

[StormNinjaPenguin]

Thanks! I will do as you suggested, I like the sound of it so it is worth a try. Coming from you, it's good to know that it has no risk of damaging the Crack.

[Paul Birkeland]

I certainly didn't imply that there's no risk, but the risk is minimal and the Crack is generally an easy circuit to repair if something goes really wrong.

[StormNinjaPenguin]

That's good enough
Thanks again for the answer! And for the Crack in general.

[TwoThirteen]

I'd like to add to this that I thought I had a bad tube, because every ~20 seconds there would be a tiny popping sound. It turns out that a little bit of isopropyl alcohol and a few Q-tips cleaning the connecting pins under the tubes fixed the popping entirely. I believe there was corrosion/buildup there. GL!

[StormNinjaPenguin]

I reply as closure because the seller is visible on the video I shared and I don't want to make a bad reputation for them. After the issue didn't go away after 2 days of uptime, I sent them a mail and they immediately sent a replacement. All good now, I prefer this 6H13C power tube over the stock GE tube.