Cryogenic Treatment of Tubes, and why you should not.

It’s a (maybe) engineer pondering things. In parts interesting, in parts long-winded, definitely not scientifically rigorous - just pondering, which I do a lot of myself. All we can really do is decide for ourselves. I have indeed thought about the "structrual" problem, and subjecting tubes to an unecessary freezing cycle. But what do I know? I’m not a structural, materials, chemical, electrical, nor tube engineer. Tubes don’t have a virtual machine or compiler for me to get into how they work.

I’ve had cryo tubes from various sources over the years. At times I thought some of them sounded "awfully" good for that tube type/brand. So when I started regularly buying sets of 6H30 and KT120 from Upscale (every 2 years or so), I would often tick the "Cryo" option, at an extra 8 bucks a tube. Did this for several sets over the years. But then just stopped - realized I wasn’t hearing a meaningful difference versus non-cryo sets of the same tubes. Got a mix of both now in my stash. But I haven’t bought cryo in years and won’t anymore.  I won’t kick the cypos out of the stash either, but it’s just a "meh" and "cool sticker" when I think about it now. Nothing takes the "exotic" feeling out of something like repitition and familiarity. 

Cryo'd anything is a marketing scam. Ask an actual metallurgist and they'll straighten it out for you.

The ability to hear a difference is a function of how resolving your system is.

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

In my own case, a few years ago I concluded I could not hear any difference between using the volume control on my DAC, which has a remote, and using the volume control on my integrated 300B amp, which doesn’t have a remote.  Since then I have made lots of upgrades in other parts of the system.  Out of curiosity I went back and compared the two again.  Now it’s apparent that not using the volume control on the DAC improves the depth of the soundstage significantly.  All of my friends can hear it’s deeper

As Einstein probably said, everything is relative.

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.