[iGrant]

Any thoughts on it. I've just sent off a complete set of GF tubes for Cryogenic treatment. Anyone had any experience with it?

If -49 degrees worked I could just put them outside , damn cold in Calgary the last few days.

[alan m. kafton]

If they are properly handled, you should be very happy with the results. My consistent findings have been increased musical information, together with a quieter background.

[slbenz]

Ian,

I would agree with Alan.  Cryoe'd tubes sound better in my Parasound/Magnepan system.  At least the ones I have tried in my Jolida JD-9 phono preamp.

Slbenz

[iGrant]

Thanks, I've been told by a few customers that the results are well worth, have actually heard on one of our 300B amps, but it was so heavily modded, it was impossible to tell what I was listening too. Moray James (of Sumo Aria fame) is doing them for me in Calgary, he's been doing it for a while now, if it works out well with the Shuguang tubes, he may be very busy . Says that you can lose some tubes in the process. I understand the theory, just never heard it before and everything I've read has been positive.

Do you buy the treated or get someone to do it after?

Thanks again.

[Philistine]

I've had cryoed and regular versions of the same tube - and likewise prefer the cryoed version in my equipment.
One of the cryoed tubes lost its vacuum (as it wasn't in service it may have got damaged).  I have heard a myth that cryoing decreases tube life, I've never researched this so don't know if its fact or fiction.
   

[mca]

Where is a reputable source to have this done? I have been wanting to try it with the tubes in my RM-200.

[twitch54]

What does one spend for such service ??

[alan m. kafton]

Ian....you can trust Moray. He knows exactly what he's doing, and further utilizes true deep cryogenic treatment.

[alan m. kafton]

I have heard a myth that cryoing decreases tube life, I've never researched this so don't know if its fact or fiction.

This is nonsense.  If anything, cryo treatment would increase tube life as the metals gain greater tensile strength (due to the compaction of the molecular structure), and likely exhibit lower electrical resistance as well. Both of these factors would *increase* tube life, not reduce it. Cryo-treated transformers, for instance, have shown lower operating temperatures and measured lower resistance. It is not a stretch to apply these benefits to tubes.

[KCI-JohnP]

Where is a reputable source to have this done? I have been wanting to try it with the tubes in my RM-200.

Mca,
Not sure if they will cryo your tubes for you but these guys have a great rep and great prices on their tubes.
http://www.cryoset.com/catalog/index.php

John

[Philistine]

I have heard a myth that cryoing decreases tube life, I've never researched this so don't know if its fact or fiction.

This is nonsense.  If anything, cryo treatment would increase tube life as the metals gain greater tensile strength (due to the compaction of the molecular structure), and likely exhibit lower electrical resistance as well. Both of these factors would *increase* tube life, not reduce it. Cryo-treated transformers, for instance, have shown lower operating temperatures and measured lower resistance. It is not a stretch to apply these benefits to tubes.

Thanks for clearing that up Alan.
In the meantime I ran a google seach and discovered these two claims on improved longevity also: 
http://www.tubedepot.com/bsctfaq.html
http://www.tubeman.com/cat8_1.htm
 

[slbenz]

Where is a reputable source to have this done? I have been wanting to try it with the tubes in my RM-200.

Mca,
Not sure if they will cryo your tubes for you but these guys have a great rep and great prices on their tubes.
http://www.cryoset.com/catalog/index.php

John

Second that!  That is where I buy my tubes and Ron is close by as well.

Slbenz

[Parnelli777]

I'm far, far from an expert on cryogenics, but it seems to me it would make more sense to cryo treat the completed metal assy. BEFORE it goes into the glass envelope. But I suspect this is not done in any case.

Anyone know if cryo treating the glass envelope has detrimental effects?

[iGrant]

Ian....you can trust Moray. He knows exactly what he's doing, and further utilizes true deep cryogenic treatment.

Yes I met Moray yesterday for the second time, he has a wealth of practical knowledge and experience and some great stories. We hope to combine our efforts down the road. If your looking to get anything cryo treated, I'd trust him, as he has come highly recommended form the local Calgary audio community. The quote I got wasn't expensive at all and if I hear what I've been told here and from what I've read it may be the best bang for the buck tweak in tube audio.

I've also read where some do the whole amp and CDP's. Anyone tried that?, I can see doing power cables, power supplies etc. Fortunately I always have demos and samples that can be tried or fried.

Thanks again.
Ian

[jules]

As I understand it the cryogenic process is intended to anneal the metal in tubes. The temperature is about -200 C so it's well below any natural conditions.

Annealing softens, rather than hardens metal but it does reduce stress, particularly at points where differential heating has occurred such as with a spot weld.

If you re-heat metal to red heat and then cool it, you can lose the annealing effect [with some metals]. There are also specific temperatures which will harden/temper metal and these are in the range of temperatures you'd find in an audio tube. So ... some parts of a tube are going to loose the annealing the moment you turn them on, specifically the heating element, though this might not matter. Some parts of the tube are going to be tempered by the heat and thus lose their annealed property. Some elements are possibly going to stay annealed or have different stress patterns to the post-manufacture state.

All up, cryo'd tubes aren't going to stay uniformly annealed so the question is ... Does replacing the manufacturing induced stresses with operationally induced stresses make sense?

Jules

[jules]

One other thing that's worth a mention ...

When tubes are made things are HOT. The glass is hot, somewhere between 600C and 1,000C depending on the type of glass and the pins are hot BUT the co-efficient of expansion of the pins is greater than that of the glass [that is they expand and contract much more than the glass], so when the tube is super-cooled there is chance that the pins will loosen in the glass so that the vacuum is stuffed ....

Jules

[alan m. kafton]

Jules......I have had dozens and dozens of tubes cryo'd over the years (by Cryogenics International).  NONE have ever been damaged, nor have any of the pins loosened. The expansion and contraction of the materials is directly related to the process utilized, and how precise that process is. Cryogenics International has been doing this over 20 years, and have their own patented, computer-controlled process. I hope this information is helpful.

[opaqueice]

As I understand it the cryogenic process is intended to anneal the metal in tubes. The temperature is about -200 C so it's well below any natural conditions.

I'm not a materials scientist (IANAMS), but I am a physicist - and I don't understand what you're saying here.  Annealing to me means you heat up a material to a high enough temperature to soften it a little, and then let it cool down to normal temperature.  That can strengthen a metal, because the high temperature allows some defects in the crystal structure of the metal to work themselves out, and then during the cooling the metal re-crystallizes to a more perfect state.  I don't see how taking a pre-existing part that's already been stressed, cooling it down and then warming it back up again is going to do that.

If you first heated a metal to the annealing temperature, let it sit for a while, then cooled it all the way down to cryogenic temperatures, and only then let it come back to room temperature - that might do something.  Cryo treating a piece of metal right after it was manufactured (so the metal hadn't been stressed much yet) might be more or less the same thing.  But cryo treating an old component - I don't know.

[jneutron]

The expansion and contraction of the materials is directly related to the process utilized, and how precise that process is.

Hmmm..Alan, Alan, Alan,,, how can you say that??? tisk tisk tisk...

What you meant was the "differential expansion rates between the different materials".  The process cannot control the expansion rates per se, nor the absolute differences in expansion, but it can prevent failure as a result of a cooling gradient caused by excessive rates and the thermal mass.


Hey there, long time no talk Alan.....hope all is well with you.

The glass to metal hermetic seal can indeed be compromised by the thermal expansion differences between the metal and the glass.  This is why most military hybrids utilize kovar as a feedthrough, as it has a better match to the glass TCE.  One drawback to kovar is it is magnetic.

Using a computer controlled ramp rate will reduce (if not remove) the possibility of breaching the hermeticity during cooldown or warmup.

Opaqueice:  if you look up "martensite finish temperature", you will find some information on this type of process.  In steels, there is a diffusionless transformation of austenite to ferrite, this being a FCC to BCC transformation.  At room temperature, the conversion is incomplete.  There will be a low temperature  called the "martensite finish temperature, where the transformation is complete.  This is the "type" of transformation utilized in cryogenic treatments.

Barrett, Nix, and Tetelman discuss this on page 311 of "The principals of engineering materials", 1973, Prentice-Hall.

Cheers, John

[alan m. kafton]

What you meant was the "differential expansion rates between the different materials".  The process cannot control the expansion rates per se, nor the absolute differences in expansion, but it can prevent failure as a result of a cooling gradient caused by excessive rates and the thermal mass.

In jneutron we trust.