[wakibaki]

Wouldn't that fracture the glass?

Not necessarily.  It depends on the rate of cooldown, the level of stress built into the glass during manufacture, and how smooth the invar or kovar is at the seals.  Rough invar/kovar surfaces can cause stress concentrations which can start crack formation if the TCE's aren't well matched.

The balance of your post is moot given this info.

I do note however, that there are significant differences between material improvements and electrical improvements to be had with cryogenic treatment.

In ferrous alloys, thermal treatment below the martensitic finish temperature causes the crystalline atomic lattice to fully change over to a final lattice structure.  This is the ol' BCC vs FCC thingy..

In the electrical realm, I've not heard or seen any reasonable effect or explanation given for any electrical changes via cryogenic treatments.

jn

Just what was the point of disagreeing with this passing remark?

A typical jneutron post, contributing essentially nothing to the understanding of the subject, but at the same time lending a degree of credibility to unfounded claims in the process of advertising the posters putative expertise. We've all heard (from you) about how smart you are jn, but in my experience smart is usually a function of the volume of useful information in a poster's output, not their claimed credentials. On that score I'll take Ethan Winer any day.

w

[jneutron]

Just what was the point of disagreeing with this passing remark?

Because he claimed that if the vendor actually cryo'd the tubes, that he expects them to crack.  Then went on that since tubes should crack, claims they've cryo'd tubes must be fraudulent.

Once the assumption that tubes will crack is casually dismissed by inspection, understanding, and actual experience, the rest of the post regarding "maybe they didn't cryo" has been rendered meaningless.  We already know that proof of audible differences has not been provided, it's always subjective claims.

I've copied your useless diatribe here so that it cannot be edited away:

A typical jneutron post, contributing essentially nothing to the understanding of the subject, but at the same time lending a degree of credibility to unfounded claims in the process of advertising the posters putative expertise. We've all heard (from you) about how smart you are jn, but in my experience smart is usually a function of the volume of useful information in a poster's output, not their claimed credentials. On that score I'll take Ethan Winer any day.

w

You lack expertise of any kind on this topic, that is quite clear.  The only thing you can do however, is attack the individual.

When you can produce intelligent discourse on a topic, I will be pleasantly surprised..

So far, you have not surprised me.

Obviously, the content of my post is sufficiently above your understanding, as the nature of your post makes that abundantly clear.

In your case, the old saying certainly applies..  Tis better to be quite and thought a fool, rather than speak and remove all doubt.

jn

[barrows]

I do  not know if cryogenic treating changes properties of metals and dielectrics in a way which would positively change sonic characteristics, but, I have heard positive results from cryo treating fuses used in the AC line input.  The difference was repeatable, and notable enough for me to make it worth the expense (which was minimal for a fuse).  For science, we would need a physicist and a metallurgist working together with some very sophisticated equipment to show changes in material properties, and then we would need serious listening tests to correlate the physical differences with sonic properties.  I doubt any high end audio companies anywhere have the kind of budget which would be able to support such research.
I see no reason to dismiss the likelihood that cryo treating does change material properties, just as heat treating changes material properties; and it certainly seems possible that differences in material properties could result in sonic improvement.
I also know of one, very well respected, high end audio manufacturer which pays to have film capacitors cryo treated for some of their products-what is interesting about this is that this manufacturer keeps this fact a trade secret, and does not use it to market their products… come to your own conclusions. 

[jneutron]

I see no reason to dismiss the likelihood that cryo treating does change material properties, just as heat treating changes material properties; and it certainly seems possible that differences in material properties could result in sonic improvement.

I tend to agree give or take.  However, my last 20 years has been spent working with cryogenics in the capacity of design, building, and testing of widgits for use in liquid helium, liquid nitrogen, and liquid argon. At NO time has there been any measureable change in either dielectrics or metals as a consequence of cryogenic treatment.  When I say measureable, I mean within the resolution of my equipment, which is typically accurate to 10 decimal places.  So while I remain open, I and the scientists and physicists I work with on a daily basis from around the planet have never experienced any measurable change in either the metals or insulators we use as a consequence of cryogenic treatment.  The biggest issue we deal with is the thermal expansion coefficients as we go from room to absolute zero +2 C.
 

I also know of one, very well respected, high end audio manufacturer which pays to have film capacitors cryo treated for some of their products-what is interesting about this is that this manufacturer keeps this fact a trade secret, and does not use it to market their products… come to your own conclusions.

My conclusion would be that somebody in the factory thinks it makes a difference so does it.  The fact that they choose to do it does not mean it made a difference.

So no, the fact that a manu chooses to do it doesn't provide factual support for the process.

jn

[Speedskater]

"jn" by measurable change do you mean in the electrical properties sense or do you measure additional mechanical properties ?

[Devil Doc]

I don't know if this is germane to the subject, but cryo treatment of gun barrels makes a difference. Copper fouling is the bane of target shooters. The stuff almost welds itself to the barrel, affecting accuracy. It's nearly impossible to clean without using heroic measures. Cryro treated barrels, for some reason, are easy to clean. A little penetrating oil and a brass brush are all that is necessary. So does cryo treatment affect metal. Yea, it certainly does.

Doc

[jneutron]

"jn" by measurable change do you mean in the electrical properties sense or do you measure additional mechanical properties ?

Electrical.  Mechanical changes do tend to occur depending on what the material is.  For wires, I use copper, nichrome, phosphor bronze for accurate measurements of cold objects, and the wires and insulation don't give an electrical "whit".  Ceramics, epoxy, Teflon, kapton, tefzel, nomex, pvc, xlpe, hdpe, none change electrically.  Physically, a different story.  Some will crack during cooldown if they are not strong enough and wrapped around a metal, as the plastics shrink faster, get brittle, then fail.

And Devil Doc, yes cryo can indeed change metal characteristics depending on alloy, history, and lattice structure.  The Q of the day is, does it change the electrical properties.

jn

[Ericus Rex]

Hey JN,

How do the results of cryo treatment differ between ferrous and non-ferrous metals?

[jneutron]

Hey JN,

How do the results of cryo treatment differ between ferrous and non-ferrous metals?

All I'm aware of with ferrous metals is the martensitic transformation temperature, and the conversion between FCC and BCC.  The mech guys tend to worry about the physical properties of stainless and non ferrous alloys because they use then as structural elements.  I only worry about the electrical qualities of the conductors and the insulators.  Especially copper and aluminum if it's pure enough, their resistivity drops about 2-4 orders of magnitude when at 4.5K.  But once returned to room temperature, we really can't tell that they've been cryo'd.

I do know that brass does something as well mechanically, but since we don't use it, I've no worry there.
jn

[Ethan Winer]

The Q of the day is, does it change the electrical properties.

And even more important, does it change the electrical properties enough to make an audible difference in the sound?

--Ethan