[Elizabeth]

So far I have used only two sets of cryo'ed tubes.
Fist one was in my VAC Standard. Took the (2) 12AX7 and (2) 12AU7's over half a year to sound great. Then I physically broke the power supply... (so sitting unused, temporarily I hope
The second put into Conrad Johnson ACT2  (4) 6N30P a month ago. Still hoping they will slowly get better.
So far my experience is the cryoed tube takes a unusually long time to break in.
Is this true?
I ask since I have so little experience.
The Conrad Johnson is seeming a little bland. but as the month has progressed I am having more hope...

[FullRangeMan]

Audiophile cryo usually is made with LN² Liquid Nitrogen that have a partial effect on align solids, particularly non metals, however this process is inexpensive. What really align metals at molecular level is Liquid Hydrogen, however LH requires cryogenic storage and boils around 20Kº or -423°F  its liquefaction have a large cost as energy is needed to cool it down to that temperature, hence it not used for audio stuff.

[Triode Pete]

Audiophile cryo usually is made with LN² Liquid Nitrogen that have a partial effect on align solids, particularly metals, however this process is inexpensive. What really align metals at molecular level is Liquid Hydrogen, however LH requires cryogenic storage and boils around 20Kº or -423°F  its liquefaction have a large cost as energy is needed to cool it down to that temperature, hence it not used for audio stuff.

Liquid Helium is "best" for cryogenically treating audio stuff!

My $0.02,
Pete

[SteveFord]

I have not found a long break-in period in my limited experience.
It's been a while but I think I used cryoset.

[FullRangeMan]

This longer than usual burn in period looks odd, as the popular Pentode current production tubes are know to last only 2K hours (average) conservatively used.

[Elizabeth]

This longer than usual burn in period looks odd, as the popular Pentode current production tubes are know to last only 2K hours (average) conservatively used.

I would guess you are referring to Power tubes. Not preamp tubes.
I have used preamp 12AX7 for several years non stop.. That is 17,500 hours...
And they were still fine...

[FullRangeMan]

I would guess you are referring to Power tubes. Not preamp tubes.
I have used preamp 12AX7 for several years non stop.. That is 17,500 hours...
And they were still fine...

Correct, power tubes current production.
THis 12ax7 was old production?

[Steve]

Years ago, I saw the price of NOS tubes getting way out of line. Today, the prices are absurd. Anyway, I designed preamplifiers  around the JJ E88cc tube (incredibly low distortion tubes). Using techniques, although critical and tough, I was able to perfect the  perfect preamplifier, out signal was the same as in signal (via special listening tests, I am retired from preamplifier business).

I have had only two reports; both times the tubes were run continuously 24/7 for ~3 1/4 years. That calculates to
~28,000 hours. One can run tubes a long time can if properly designed.

cheers

steve

[rollo]

Not true. Elizabeth if that 6H30 is a Sovtek you will wait forever. They are bright and slighty hard. Find a pair of Reflector 6H30. Tubes in general take 100 hours. Some power tubes longer.
I have found that Cryo treated tubes take another 50 hours than standard tubes. Cryo does change character to warmer usually. Those tubes with excessive hours may still work but I'd bet a fresh set will surprise you.


charles

[rollo]

Liquid Helium is "best" for cryogenically treating audio stuff!

My $0.02,
Pete

   CORRECTO MUNDO  and expensive. That is what you use I believe.


charles

[rockadanny]

Glass contracts when cold. Are you ever worried that super-duper-cold may compromise the tube's glass seal?

[S Clark]

Glass contracts when cold. Are you ever worried that super-duper-cold may compromise the tube's glass seal?

It depends on the difference in the coefficient of linear expansion in the glass and the metal prongs.  Ideally, they should be the same, expanding and contracting at the same rate.   

[rockadanny]

Ah, thank you SClark 
I've always wondered about that.
Hopefully everyone's tubes that get frozen are ideal.

[br3098]

I'm not trying to start a flame war here (really!), but I have to say that I am continually surprised when otherwise rational adults fall for audio tweaks and scams.  Cables are #1 on my list of the most egregious audio BS topics and "cryo'd" tubes (or cables or whatever) are second on my BS hit parade.  Sorry folks, but there is no such thing as a cryo'd tube and there are no physical or sonic benefits to cooling a tube.  In fact, cooling any joined metal parts below approx. -50 degrees C increases stress on any joint (crimped, soldered, brazed or welded) that has not been specifically designed for low temperatures.

That's not to say that cryogenic processes are not useful and beneficial in metallurgy, they are; typically as hardening processes and a the process almost always introduces a significant degree in toughness which is metallurgy-speak for resistance to shock.  But grain realignment and occlusion displacement (the most widely claimed benefits of post-manufactured cryo treatments) only occur when the process is employed as the wire is cold extruded or drawn.  I assume that most of you have had a high school or college chemistry class.  If you remember seeing a P/T (bunny ears) diagram you should know that certain processes only occur at or near phase boundaries.  In order to achieve a change of mechanical properties in the material it has to be cooled to approx. -185 degrees C.  You can certainly cool a bare wire to that temperature, but you can't cool a tube or most processed assemblies to that temperature for a several reasons.  Here are two:

First, you can't really supercool a tube down to near absolute zero.  Yes, you could drop a tube into a solid/liquid Ni slush bath.  You would certainly cool the glass envelope, cop and pins.  But the hardware inside the tube is encased in a vacuum (remember?) and any cooling of the internal structure would have to come from conduction.  There is no way of knowing if and when all the elements reach target temperature.  Plus there is a significant risk that some components (bakelite/plastic/ceramic caps, mica plates) would not survive at those temperatures and may fail.

Second, crogenic treatment of metals also requires pressure.  Remember my mention of the P/T diagram?  The more the thermal energy state can be reduced (lower temperature) the less pressure in required.  But ALL cryo processes require SOME pressure.  How do you pressurize the inside of a tube?  Or the outside for that matter (successfully)?

There are some materials that do benefit from cryo treatment at near atmospheric pressure - silicon wafers, silicon chip assemblies and parts comprised of silicon alloys are good examples.  But cryo'd tubes?  Please...
 

[Elizabeth]

The innards of a tube exit the glass through the steel pins... Steel is an excellent conductor.
And the pressure thing? I would love to have you make a link to were you found that.

[jules]

I'm not a cryo fan myself but I'd suggest the physics towards the end of br's post is a little out.

As I understand it, when tubes are cryoed [spelling?] the temp is lowered very gradually over a long period of time [and at the end of the process, raised over a longer period of time]. This is to minimize stress and also to give the process time to work when the low temp is achieved. Some tubes still fail of course.

There's two ways the temp inside the tube can be lowered, despite the vacuum. One is. as Elizabeth says, by conduction through the pins. The other way is by radiation. Heat radiates away from higher temp [energy] points to lower temp [energy] places. It's not so much that the cold gets in, as the heat gets out. Best example of heat traveling through a vacuum ... the heat from the sun traveling through space to earth. It would take very little time for the heat energy inside  a tube to escape and for the tube to reach the same temp as its surroundings.

All that aside, I've yet to see any explanation as to why cryoing should improve the performance of a tube.

[Steve]

The innards of a tube exit the glass through the steel pins... Steel is an excellent conductor.
And the pressure thing? I would love to have you make a link to were you found that.

Absolutely concur with you Elizabeth, as well as infra red and other spectrum wavelengths
of energy emanating from the internal structures. I also agree there is no pressure required.
 
As a general topic, some years ago, I was discussing the subject with one from Chitown who uses an
electron microscope in his employ, who sees the rearrangement of atoms after cryoing materials
with liquid nitrogen. An executive friend of mine who used to work in top government research,
also works with cryoing, immerses in liquid nitrogen, ~ -320 in audio work.

Although I have experiences, I won't go any further, let that be for others.

cheers

steve

[Tom Bombadil]

Seems to me that if one wished to "improve" upon the metals used within a vacuum tube, that one would subject them to cryogenic treatments before inserting them into a glass envelop.  Treating the many different materials within a vacuum tube afterward by subjecting the entire tube to ultra cold temperatures seems like snake oil to me.  The article linked below asks why a company like Mullard, who possessed all of the facilities to cryo tube materials and who had good reason to build very long-lasting tubes for critical military usage, never cryo'ed tubes. 

https://blog.thetubestore.com/cryogenic-treatment-of-tubes-an-engineers-perspective/

I will add that I've never purchased a cryo'ed tube.  I've conducted many comparisons over the years of cables, tubes, DACs, preamps, amps, etc., but the whole cryo thing seems so farfetched that I've never bothered. 

[Elizabeth]

ahh lets see. The thread is about :" I think cryo'ed tubes take forever to sound great. True or not true?"
Thus the thread is NOT about the merits of cryo-ing tube, nor about that some folks think it is 'whatever they think'. It is about the topic question. Which is. repeat: " I think cryo'ed tubes take forever to sound great. True or not true? "
So I suggest if you have not compared cryoed tubes and regular tubes and noted time of break in in any way.. I suggest you start your own thread about what ever you are interested in spouting.

[rollo]

   NOT TRUE. Just different. All they need is to burn a least path of resistance in. About 50 hours. I have numerous tubes cryo treated.


charles