Why "Cryo" anything?

This is an interesting thread. I’m not really sure why some are taking the stance that “if it sounds better, don’t worry about why”? This is the Tech Talk forum and I believe the point for Ejliu starting this thread was to probe if anyone has a sound understanding of why “cryo” may make a difference, not necessarily anecdotal evidence that “cryoing” improves the sound of any particular piece of equipment.

As a metallurgical engineer (BS – University of Illinois, 1989 for you credential seekers), I too have a guarded skepticism regarding the validity of potential mechanisms for the perceived changes/improvements attributed to cryoing mentioned in this thread. Please understand that I also rely on my ears primarily to guide me toward better sound. Since this activity is subjective in nature, I clearly don’t fall into the trap, sometimes typical of engineers, that if it doesn’t measure better/differently, there can’t be an improvement/difference. I hear what I hear…psychoacoustical explanations aside! But clearly, the point of this thread was the "WHY", right?

The asking of “why” is a very important step in my opinion. Technology does not advance without this step. A deeper understanding of the physical world and using this knowledge to design more advanced products is central to the technological world we live in. With all due respect to the rare “black magic” inventor, it’s the science that drives true advancement.

No one in this thread has yet offered credible science to explain “why” cryoing changes the sound of a component. What has been offered is speculation that whatever happens MAY be caused by a diffusionless phase change similar to a martensitic transformation. Since the temperatures involved (RT – LN2) are so low, this really is the only possibility, IF the changes are caused by a reorganization of the crystal lattice. A mechanism involving mass transport (diffusion) would simply take way too long, possibly hundreds of years to accomplish.

I have a several issues with the martensitic transformation explanation though. First, transformations of this nature are not equilibrium transformations. They rely on “trapping” a non-equilibrium phase, usually through rapid cooling, leaving no time for the equilibrium phase to nucleate and grow. They occur very rapidly, in some cases at the speed of sound. They are basically a shear transformation, a small shift or rotation of a lattice plane, not unlike a seismic shift of plates in an earthquake. Since, in the case of IC’s, PC’s or SC’s, there hasn’t been any suggestion that cryoing must take place immediately after the Cu is solidified or drawn (strain-induced), this suggests that for a martensitic-type transformation to take place, an equilibrium phase different from RT equilibrium phase must be present on a Cu/Alloy ternary phase diagram at temperatures near LN2. Perhaps this is true, but given the extensive research in cold-temp physics, I would have assumed that the phase diagrams of commonly used materials would have been updated by now??

Secondly, if this were indeed true and the phase diagrams not understood/updated at low temperatures, then what would be the purpose for holding a component at this temperature for extended time, longer than necessary to get the temperature equalized? If it is a diffusionless transformation, time has no bearing on the volume fraction of the non-equilibrium phase present, only temperature and the rate of change of temperature are important.

Thirdly, very special conditions need to be met to “practically” induce martensitic transformations. By practical, I mean the cooling rates have to be reasonable. In steel, you have to alloy carefully to stabilize austenite at low enough temperatures to allow real world cooling rates to bring the piece to Ms before the onset of ferrite/pearlite nucleation. Not all materials can be forced into this type of transformation. Are we to believe that composition is unimportant for this transformation at cold temperatures, given the relatively poor heat transfer of LN2. If this were true, I would expect science would have stumbled upon this phenomenon a LONG, LONG time ago.

Finally, if this type of transformation were indeed happening, simple x-ray diffraction techniques could demonstrate this beyond a reasonable doubt. If the lattice structure changes, it is easily measurable!!!

I mean no disrespect to those that posited their thoughts on why/how perceived changes in sound may come about through cryoing. To be honest, though, without specific science to support it, it is just a guess. If anyone has access to peer-reviewed papers on the presence of meta-stable or non-equilibrium phases at low temps for the materials in question, please e-mail me or post it here. It would be wonderful for all of us if there was solid science supporting this…further advancement would then be just around the corner!!

Regards,
Jordan

Lugnut, I didn’t suggest the thread should be limited. I questioned why others chose to limit the discussion by suggesting that “if it sounds better, don’t worry about why”. Whether you like it or not, that IS a limiting statement!! This particular issue is unique in that it is much more easily investigated through theory as well as measurement. We can measure structural and compositional changes in the lattice very precisely. In the case of cables and other equipment, the number of variables and their interactions oftentimes precludes easy analysis of why something sounds better.

Furthermore, you have to admit that the number of different materials that are being cryo’d and claims of its superiority are a little over the top. Golf balls, fishing hooks, tennis rackets and pantyhose (no joke) all benefit from cryoing? All grades of steel, Aluminum, Copper, Silicon, plastics, composites all benefit from cryoing? This is the “hype” surrounding cryo treatment and it should make all of us at least suspicious of the claims, particularly if there is an economic motive by some, right? If you tried it for a given application and feel secure in the improvements, then great, but certainly you would agree that this anecdotal evidence would not necessarily apply to a different application with a different material, right?

As an “MSE”, I’ll concede that for a few specific grades of steel, cryo treatment is sometimes used to optimize a given property. Fortunately for us, it doesn’t put us into an “emotional tailspin” because there is valid science behind it. For highly alloyed steels, the original processing may have resulted in some retained austenite still present at room temperature. Lowering the temperature further can force this retained austenite to transform to martensite. This IS easily measured and understood! In almost all cases, this would be followed by tempering at somewhere close to 300C to allow some of the dislocations created from the transformation to relieve themselves. If you followed the same treatment for a grade of steel that did not have retained austenite, you get NO change in structure. This IS easily measured and understood!

Surely you don’t judge the validity of ideas based on whether an A-goner has his system posted or not, do you? If it helps you to take my intentions seriously, I have Magnepan 3.6 speakers, Parasound JC1 amps, Rowland Concerto linestage, APL Denon3910 Universal player, Purist Audio Museaus interconnect and speaker cables, and a PS Audio UPC-200 conditioner. My room is dedicated and I use ASC tube traps, homemade Helmholtz resonators (Argent Room Lenses), and Auralex diffusers. You have made some sweeping statements in your post trying to categorize those of us that are trying to understand the physics of THIS particular issue. Perhaps I’m wrong, but from your comments it seems as if you think true audiophiles are under attack in this thread from the “naysayers” and must band together to defeat them? I always thought I was a “true audiophile". Given my wife’s puzzled expressions and general disdain for the UPS delivery guy, I just assumed this was good enough empirical evidence to confirm that. Perhaps not?

Finally, I’m sure you’re not serious with this statement:

My offer to Ejliu to heat treat and cryo some brake pads for him is still open

I’m sure you are just saying this to make a point and wouldn’t actually want someone to be injured to prove it? Besides, from my read on Ejliu’s posts, he was only trying to suggest that heat treatment before cooling was necessary to change the structure and NOT that this change would be good and/or smart.

Geoffkait, actually I think you just made Ejliu's point:

a discussion between those that have tried cryo treatment and hear the difference and those that have not tried it, yet demand a scientific explanation - one that is not available, at least one that satisfies the doubters.

Substitute in religion and you get:

a discussion between those that have tried "religion" and know it to be true and those that have not tried it, yet demand a scientific explanation - one that is not available, at least one that satisfies the "non-believers".

There is an element of “faith” in this hobby given the difficult nature of quantifying differences that are heard. I’m by no means a “if it doesn’t measure differently, it can’t sound different” guy partly because for a complex system such as an audio system, it’s not clear that enough precise measurements of all the important variables -- and there interactions -- could be accomplished, nor would it be clear (to me anyway) how exactly to interpret them. I use my ears to guide me, but I also recognize that my subjective opinions aren’t necessarily objectively true. The cryo issue (to me) is a different animal because it is such an easily investigated process. It involves (mostly) a single material (an area I have reasonable knowledge in) put through a simple thermal cycle. I’m sure Ejliu’s interest in this was for at least similar reasons?

BTW, I have cryo’d ACME silver plated outlets…they were $5 more than the non-cryo’d version.

Excellent post, Lugnut...I figured this debate was just getting us all a bit too excited.

I do differ from your opinion that the "naysayers" are suggesting that there is no difference in sound. Perhaps I'm only speaking for myself (I don't think so?), but no one has directly said that cryo'ing does NOT make a difference. Some of us have tried it, some have not. My take on the discussion has been that some of us with specific knowledge of materials have questioned the "reasons" some have attributed to the difference, not really that there are no differences. This certainly doesn't rule out mechanisms we are unaware of, but the metallurgy is very well understood, so I'm fairly certain that we need to look elsewhere for the answers.

Autio, I agree that our ears are wonderful devices, but one component of hearing is perception and this is not always reliable. I've found my moods, sickness, exhaustion from a workout, etc all affect how and what I hear. Also, when I listen critically with a friend, sometimes afterward I find myself reversing my thoughts on further listening by myself. What I'm saying is MY hearing/perception is not always as reliable as I would like it to be. Maybe others don't have this problem? Ultimately, it is still the only tool we have to measure our enjoyment of a given component. I'll leave it at that.

Regards,

Jordan