Cryogenic Treatment of Tubes, and why you should not.

More Binary thinking. A metallurgist will tell you there are benefits in specific application. But you are also a cable denier so I would expect such biased opinions based on zero experience. Cryogenics can change the micro-structures therefore eliminating asperities in both non treated and heat treated materials. 

@roadcykler AI can help you here.

1. Phase Transformation and Microstructural Changes:

1. In heat-treated steels, a portion of the structure can remain as retained austenite (RA), a soft and less desirable phase compared to martensite.

1. Cryogenic treatment promotes the transformation of retained austenite into martensite, resulting in a stronger and more durable microstructure.

1. This transformation also leads to a more uniform grain structure and reduces imperfections or voids in the metal's microstructure, making it denser and smoother.

2. Precipitation of Fine Carbides:

2. Cryogenic treatment enhances the carbon structure of steel, leading to the precipitation of fine eta-carbides.

2. These carbides act as binders, supporting the martensite matrix and improving the metal's wear resistance and reducing the impact of asperities during contact.

3. Stress Relief:

3. Residual stresses are inherent in metals due to processing steps like casting, machining, and heat treatment.

3. These stresses can create weak areas prone to cracking and fatigue failure.

3. Cryogenic treatment can effectively relieve these residual stresses, contributing to a more uniform and stable structure, which indirectly reduces the potential for asperities to cause issues like wear and fatigue.

4. Surface Roughness Reduction:

4. Studies have shown that cryogenic machining, utilizing liquid nitrogen as a coolant, can significantly improve surface roughness compared to traditional methods.

4. This reduction in surface roughness can be attributed to the decreased friction and heat generated during the machining process under cryogenic conditions, leading to fewer defects and a smoother finish, according to ScienceDirect.com. 

Benefits in reducing asperities

• Improved Wear Resistance: By reducing surface irregularities and promoting a denser microstructure, cryogenic treatment enhances the wear resistance of metal components, increasing their lifespan.
• Reduced Friction: A smoother surface with fewer asperities results in lower friction between contacting surfaces, leading to reduced heat generation and energy loss.
• Enhanced Dimensional Stability: Cryogenic treatment can increase dimensional stability and reduce the likelihood of warping or deformation, which can be critical for precision parts.
• Increased Fatigue Life: The reduction in internal stresses and the creation of a more uniform microstructure contribute to increased fatigue resistance, making parts less prone to cracking under cyclic loads. 

Examples

• Cutting Tools: Cryogenically treated cutting tools, like drill bits and end mills, demonstrate improved wear resistance and achieve better surface finishes on machined parts.
• Engine and Drive Components: Automotive parts such as brake rotors, transmissions, and clutches benefit from increased durability and reduced wear after cryogenic treatment.
• Aerospace Components: Satellite parts, optical housings, and weapons platforms can be enhanced through cryogenic treatment for improved performance and longevity.
• Medical Instruments: Surgical tools and scalpels treated with cryogenics benefit from improved hardness and wear resistance. 

It is important to note that the effectiveness of cryogenic treatment in reducing asperities and improving overall material properties depends on various factors, including the type of material, its composition, and the specific parameters of the treatment process. 

Or you have confirmation bias. Where did you get this $30K benchmark from?

Or is it just an arbitrary number (say yes cause it is) 

If your whole system is below ~$30k, there’s an awful lot you’re not going to be able to hear.

My feeling about cryo’d power tubes is the stress from extreme temperatures weakens or makes brittle, the center alignment plastic guide.

I am in the camp that Cyro (on TUBES) does make a difference. At first I thought how can CRYO process improve the sound. As a side note, where I used to work (Space and Satellite) R&D / Manufacturing, we use CRYO machines to change the metallurgy molecular structures of components for the programs we build. So CRYO is not snake oil, but proven to work for certain Applications, BUT for Music? Hmm.

So, a Friend and I purchased 2 sets of the same tube, one CRYO and one not (SED winged C EL34) and did the proper break in on both tubes. when the time came, we listened and boy, we hear a difference, Not Night and Day difference but there is a difference. 

To me, if you have a resolving system (which we had) CRYO may? make sense. If not resolving enough, dont bother. just like speaker cables and power cables. it all depends on synergy and weakest link.

That's just my opinion.

Machine Tool Cryogenic Treatment

This doesn’t prove anything about audio tubes, but I wouldn’t argue with the proven physics demonstrated in these other applications (above link)

I can certainly see why the more adventurous tube dealers would experiment with cryo. It may be an experiment paid for by the buyers, but the buyers are willing to be experimented with. It's an understandable urge. Some particular resolution of the question may one day rule, and it may have been hinted at by the machine tool manufacturers' experience.