Cryogenic treatment of tubes? Anyone with experience positive or negative?

The idea of Cryo'ing the tubes is to relax the metal parts to allow the  shapes to settle sort of it also improves  the electrical properties including less electrical resistance . similarly NOS tubes that have been sitting for a long time  don't need this because they have naturally relaxed over time. if the parts were already from old metal let say then you wont get as good of a change with the treatment. Some metals react differently as well so you get various results. if its cheep then its worth it, if done right, if not done right it can actually damage the tube and reduce the life of the tube. best way is to stick the tubes on a shelf for 50 years, oh that's NOS.

Not wanting to be the contrarian here but I have had very good results with Gold Lion 12 AU7s from Cryoset.  The pair in my linestage just stay quiet!  I have two more of the same in boxes in the stereo room closet waiting...

I too have the Gold Lion 12ax7 gold plated pins and Cryo treated that I use for my line stage, very quiet and very detailed sound. I highly recommend it.

Generally speaking, almost all materials benefit from Cryo, not only steel and aluminum tools because they become harder, less brittle, stiffer, more durable, don’t ring as much, etc. Many audio items benefit from Cryo for the same or other reasons, glass, metal, plastics, tonearms, cables, capacitors, resistors, CDs, records, etc. etc.

I have never heard any difference, when comparing from the same batch lot.

But I seen/heard from a few customers now their tubes got noisy or flared and died after cryo’ing.
If you guys think about it Cro’ing your precious tubes is great way to make them unreliable.
The glass tube envelope vs the palstic/bakelite base v metal pins, will all expand and contract at different rates when cryo’ed.
Therefore having a great chance of unsealing the glue bond between the three and the tube loosing all or part of it’s vacuum.

Cheers George