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RE: What ever happened to cryo treated tubes?

Posted by TubeAcolyte (D) on April 3, 2014 at 11:48:26

In Reply to: What ever happened to cryo treated tubes? posted by airtime on April 3, 2014 at 06:39:01:

Cryo-treated tubes have always remained a curiosity, but I'm really skeptical. I'm not super scientist, but I know a thing or two about physics and chem. It could be true, but the overall matter is confused at best.

For me, certain things come to mind
- The extreme cold should in theory make the materials of the tube contract. I would be worried about physically damaging the tube. What about pin-to-glass seals in the base? What about solder and weld points? Does the mica contract at the same rate as the glass?
- A tube is still a large device, and there's some amount of play and "give" between all the components. Take grid posts, for example, which sometimes feature grooves to help align and secure the grid. Would a treatment further secure the grid, or would the post freeze first, and potentially "pop" the grid out of place like a cracking ice out of a tray?
- There's some garble about molecular alignments in metals and whatnot. Frankly, I dare anyone to tell me exactly how a copper-nickel alloy reacts to drops in temperature versus thoriated tungsten or gold. I cannot readily find the information.

Looking at people's impressions of these products, I get the feeling it's just really good cherry-picking, and not the cryotreatment. Reading the reviews, we generally hear about better frequency extension, more lively soundstage, lower noise floor, etc. Frankly, are those not all attainable characteristics via better testing and matching?

So, I figure it's like this. Suppose we have a VERY stringent testing and matching process. First, the tube must operate for a sustained time at maximum or near maximum parameters. Second, the tubes are not only electrically matched, but sonically as well; each tube goes through a battery of frequency tests to determine which are most alike across the control grid's operating points.

Out of the gate, you'll have only maybe 2 quads out of 100 tubes that get the passing grade, at which point the quality and labour will hike up the tube's price. Assuming you knew it was entirely safe, what is it to throw those sets through a cryotreatment process? At the time of purchase, the buyer gets a sense of added value. For the seller, they have an already expensive quad which is either made more expensive still, or sells on the merit of being well-selected with the added "free" bonus of a cold bath. Note how there are no special warranties for the Black Sable products at the TubeDepot...

The site linked below claims a boost in transconductance after the treatment, but there's not even a little data table to explain with some numbers to even tickle us.

So, I say HOGWASH til someone develops a testing process similar to the one I described, replicates the cryotreatment process, buys a lot tubes, runs a series of comparisons and control tests, and provides solid tangible data. Really, all you need is 2 quads (one perfectly matched, the other so-so) which you divide into pairs after.
- Pairs 1 of the PerfectQuad and So-SoQuad get the cold bath
- Pairs 2 of the PerfectQuad and So-SoQuad are your control sample

Measure the characteristics before and after treatment. And voila, the answer no one wants to truly openly publish...

One shaves best when the razor is run under cold water. That said, tubes do not grow beards.
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May your tubes be lively, warm, and long-lasting. Holy be thy heater.

• The Claim...   (Open in New Window)

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