Cryogenic treatments - an experiment.

[zaphod_phil]

Almost all the valves I have are different from each other, as I like to experiment a lot. And I wouldn't want to cryo one half of a matched pair of power valves either. I do have a couple of RCA 12AT7s, however, which I could send one of to you, to try freezing. However, I doubt that my ears would be golden enough to hear any very subtle differences....

[Chappy]

Ancient Mariner

I have heard that this freezing process helps to cure microphonics. If you want I could send you a couple of old used military valves to test this theory. A 12AX7 that is slightly microphonic, and a 12AT7.

Chappy

[sjfirebird]

Do recordings before and after cryoing the tubes, the EPI Jr. would be a good test bed due to having one of each tube, least number of variables.
Then put the samples up on the board and let the results be debated.

[AncientMariner]

Do recordings before and after cryoing the tubes, the EPI Jr. would be a good test bed due to having one of each tube, least number of variables.
Then put the samples up on the board and let the results be debated.

I had considered recording, but there arfe several reasons I quickly abandoned the idea, mostly to do with occasion to occasion consistency and the ability of a mic to actually capture what our ears really hear and our fingers feel. From experience, playing amps with different valves is an almost tactile experience, and tone alone isn't enough IMO (now we really ARE into snake oil ).

Chappy - I'm not sure about that yet, and I'm certainly not claiming it. Thanks, but I'll pass for now - maybe later.

ZP - I've got another pair of 6L6s (same type, but marked up as GTs: came yesterday) courtesy of the 'bay. I'll listen to them and if the sound the same I'll send them to you for confirmation. You mark them and send them back, I'll treat one and return them both again, if you're game.

[zaphod_phil]

Sounds a fair idea to me...

[tubetwang]

A true Audiophile will have everything cryoed...

Why stop at the tubes?

I say cryoed the whole amp.

Wait!!!

While at it...cryoed the guitars, strings and cables, effects, cables, power conditioners.

Don't forget picks!

[billv]

Actually & fwiw, I play those Blue Steel strings. Not sure why, but they float my boat. However, I keep breaking the high E (.010) so I've learned how to play without.

Of course, I now have great tone for certain covers: Cold as Ice, Ice Ice Baby and Freeze Frame.

[AncientMariner]

You should try this company - they can even treat the player.


ZP - email me te rt l at d sl ab s dot co m if you want to try those valves.

[dotfret]

Well, it makes me think - my observations...
Cooling will affect the crystal state of metals and alloys. There is a story that the reason Napoleon did not beat the Russians was because the tin alloy buttons on the uniforms of his troops became brittle in the subzero Russian winter, and fell off. The troops were too busy holding their pants up to shoot at the Russians! A trivial example, but a practical one...
To cool the entire valve is a very general approach. It is difficult to say which components will be most affected, and how. Will the cooling effect be less if the pins are not dipped in tne nitrogen? Dipping the pins in the nitrogen will certainly make them brittle, so care must be taken during insertion and removal. The glass will be affected, even if it doesn't show - it will have a greater likelihood of cracking in the future, although this could be 100 years down the line. Glass is an undercooled liquid - it should crystallise at room temperature, but it takes hundreds of years to do it - thermal stress can reduce that time.
Because there are so many components that are affected within the valve (cathode, cathode coating, grids, anode) it would be hard to guess where the improvement is coming from. One way would be to use a tester on a valve before treatment, after a short treatment, and after a long treatment. It would have to be done on the same valve to remove the manufacturing tolerance variables. The only lead you can get from subjective testing is that if the effect lessens in a short time, that would be due to the cathode returning to its original state.

[Cathode_Ray]

Well, it makes me think - my observations...
To cool the entire valve is a very general approach. It is difficult to say which components will be most affected, and how. Will the cooling effect be less if the pins are not dipped in tne nitrogen? Dipping the pins in the nitrogen will certainly make them brittle, so care must be taken during insertion and removal. The glass will be affected, even if it doesn't show - it will have a greater likelihood of cracking in the future, although this could be 100 years down the line. Glass is an undercooled liquid - it should crystallise at room temperature, but it takes hundreds of years to do it - thermal stress can reduce that time.

Re glass; Isn't this how PYREX oven-safe glassware is made?
Re metal; This slow cooling process is a metal tempering process as well - if it makes 'em brittle it makes em HARD as well!

[Jack_Rackamm]

The bind test, while interesting fail to prove that the cyro process is responsible, Maybe that tube just happened to be better from the start? We'll never know...

As for low temperatures buisness, as a physics that studies zero temperature quantum phase transitions (among other things), I'd be hard pressed to make as bold statements as some that were made in this thread so far "on the fly". I would have to double check quite a few things first

[AncientMariner]

I had a 'matched pair' of Fender badged Sovtek 5881WXTs that I bought by mistake (sold as 6L6 GCs) that were utterly dark, dull and lifeless. YUK! I've A/B'd both, and they have the same tone. They were obvious candidates as being otherwise useless.

Obviously it wasn't a blind test then, but they did both a have a very similar tone. Probably not absolutely identical, but close enough that I couldn't easily spot a difference between them. If they had been this different then I'd have thought "oh, one good valve and one bad valve - crappy pairing".

Sure it proves nothing, but as a major skeptic initially myself I've been compelled by the evidence of my ears, poor as they are.

FWIW I have at least one volunteer already who will send me some valves that sound similar to him. I'll treat one and send them back blind. If he can't hear a difference (and I think I can prior to shipping) then I'll conclude it's my ears/mind fooling me.

[dotfret]

For the benefit of Cathode_Ray - chilling does not make metals hard - it does make them brittle and less malleable - and no, this is not how they make Pyrex. Pyrex contains boron and chilling is not part of the process. Skin-hardened oven glass was made by rapid cooling as a cheap competitor to Pyrex a long time back, but if it is chipped it explodes in the oven, so it was banned thirty years ago and more. Valve glass is to Pyrex as Fudge is to Treacle toffee. I do agree that it should be OK to chill a valve down to liquid nitrogen temperatures - but the slightest scratch on the envelope and I would be very wary.

[AncientMariner]

For the benefit of Cathode_Ray - chilling does not make metals hard - it does make them brittle and less malleable - and no, this is not how they make Pyrex. Pyrex contains boron and chilling is not part of the process. Skin-hardened oven glass was made by rapid cooling as a cheap competitor to Pyrex a long time back, but if it is chipped it explodes in the oven, so it was banned thirty years ago and more. Valve glass is to Pyrex as Fudge is to Treacle toffee. I do agree that it should be OK to chill a valve down to liquid nitrogen temperatures - but the slightest scratch on the envelope and I would be very wary.

I think the danger of 'explosion' due to extreme internal stress is unlikely with a valve envelope. At school we used to make explosive teardrops by dropping molten glass into iced water. However the valve envelope will have already been annealed and the cooling process used here is gradual, rather than effectively instant.

And yes, you're quite correct about pyrex being very different stuff to conventional glass. However I would expect valve glass to be somewhat closer to pyrex than ordinary borosilicate stuff, considering how it has to withstand continual heat and cool cycles and manual handling while retaining a thin wall for heat dispersion.

[MichaelJ1965]

I have conducted about three minutes of research and the result is that if AM had posted the technical specs first then he would have been told that was the wrong approach, this is music not science. (i.e. tweak to your ear not the scope signal/spectrum analyzer signal/voltage reading)

Example 1) search for sozo and see if anyone did (or recomended) a double blind test
Example 2) search for carbon comp and see if anyone did a double blind test

My four minutes of research last year concluded that different tube can sound a lot different.

I personally believe that he hears a different tone with the cryo tubes.

[dotfret]

Not much danger of explosion, that is what happens with chipped cold toughened glass. The danger is that a scratch or chip could easily turn to a crack, especially in those brief periods at room temperature during transfers.

[mattbrew0]

think someone beat you to the punch
http://cgi.ebay.com/2-Cryo-Sovtek-12AX7 ... dZViewItem

http://cgi.ebay.com/2-Matched-Cryo-Sovt ... dZViewItem
i don't know if these will open directly, but i saw these yesterday, i smell the pet rock of tubes.. or maybe i'm just being synical, but the theory is interesting, mattbrew0

[dotfret]

Not quite beaten to the punch - just a DIY version. All you need is a tissue culture lab, a freezer and an AncientMariner.

[AncientMariner]

It was the 'pet rock' thing that made me want to know either way.

[clyde]

Interesting that you could always pick out the cryo tube (valve, sorry). What
I wonder is if you could have picked it out before the cryo treatment. As someone else pointed out, maybe it sounded the same before. I wonder if a distortion analyzer or curve tracer would show signicantly different results before and after. Listening tests are *so* subjective.