shrink wrapped tube?

[GLFSHNT]

The 12AX7 preamp tubes on my 65 Lil Elvis amp have a heavy shrink wrap covering them. One of them also has several large O-rings over the shrink wrap. It looks like the intent is to allow the tube to get as hot as possible.  I have not seen this before. Is this a "known thing" to do with preamp tubes?
I replaced the tubes without all the wrap....  Amp sounds good.

[sluckey]

I have never seen shrink wrap (I assume you are talking about heat shrink tubing?) placed on a tube, but I have seen O-rings used to reduce microphonics due to tube vibration. That's probably the intended use in your amp.

[GLFSHNT]

That's possible  one of the 12Ax7s was "bad" microphonic.

I think it was, from the factory with the heat shrink covering.   
I send a note to 65amps but have not received a reply.

[SILVERGUN]

Mesa Boogie sells these

[sluckey]

Aw, that's cute. Think I could get some with my name on them? 

[shooter]

Aw, that's cute.

is that for modesty or safe tubing

[sluckey]

yes

[PRR]

> Think I could get some with my name on them?

https://www.heatshrink.com/content/custom-printing.asp

About $0.80/inch for 12AX7-size tube, min order 25 (inches? reels?)

[shooter]

Thanks PRR, I now know 1pt = 1/72" !  Not too sure I'll retain that