Cryogenically treated vacuum tubes...?

[mpeg2]

... the growing use of amorphous metal which uses an extreme and fast temperature shift to affect a phase transition which gives maximal disorder in the metallic structure; a LACK of grain structure. This metal has many useful properties, but it ain't happening by taking various metals and plunging them into LN2. ...

Wow, a blast from the past. My PhD research actually involved looking at the effects of radiaion on inducing crystallization in amorphous metals. To make the starting samples, I did what's known as splat cooling - dropping a small blob of liquid alloy between massive Cu plates - which slammed together and produced cooling rates of millions of degrees per second. Note - this is liquid - solid too fast to crystalize. Totally out of scope for LN2 cooling of a solid. Making amorphous metals only works for specially selected alloy compositions as well...

Rich

[fyl]

I'm wondering if this is near total BS or not.

You can remove the near. This is 100% pure unadultered BS.

[tubeswell]

Hmmm... The only reason you would make something colder, is that if it was so hot you needed it to be cooled down to prevent self destruction (like as in the hadron collider, which I understand needs to be kept somewhere near absolute zero because of the energy dissipation). Maybe if the tubes were fitted with a cryo-radiator which was run from a tank of liquid nitrogen somewhere in your amp, you could bias the tubes really hot and get some interesting textures. Or maybe not. But this wouldn't be a for-real tube amp would it? The resistors etc just wouldn't heat up and drift in the same way. I like my hot little tube amps the way they are.

[tedmich]

Wow, a blast from the past. My PhD research actually involved looking at the effects of radiaion on inducing crystallization in amorphous metals. To make the starting samples, I did what's known as splat cooling - dropping a small blob of liquid alloy between massive Cu plates - which slammed together and produced cooling rates of millions of degrees per second. Note - this is liquid - solid too fast to crystalize. Totally out of scope for LN2 cooling of a solid. Making amorphous metals only works for specially selected alloy compositions as well...

Rich

I a scientist too...

a recurring observation for me is little "digested science bits" in the popular press followed by a commercial venture which name checks the research with an irrational product...

this is VERY prevalent in my field (biochemistry) with nutritional findings "i think I heard something about that on "the view" so I guess I'll take this supplement which goes through me like s through a goose...."

my favorite truism of modern life: "If it don't make sense it must make money"

[tedmich]

Hmmm... The only reason you would make something colder, is that if it was so hot you needed it to be cooled down to prevent self destruction (like as in the hadron collider, which I understand needs to be kept somewhere near absolute zero because of the energy dissipation). Maybe if the tubes were fitted with a cryo-radiator which was run from a tank of liquid nitrogen somewhere in your amp, you could bias the tubes really hot and get some interesting textures. Or maybe not. But this wouldn't be a for-real tube amp would it? The resistors etc just wouldn't heat up and drift in the same way. I like my hot little tube amps the way they are.

I will soon market a system for "isothermal tubes" TM which will incorporate a little insulated housing for the tubes and a sophisticated PID controller for the heaters; you will be able to fine tune the tube temperatures from 60-121C and forced convection will assure tube temperature uniformity within 0.1C...it will sound like $1M bucks but only cost a fraction of that

[Bruce / Mission Amps]

Well OK...
Keep in mind I have ZERO experience in this so my tests are truly going to be "seat of the pants" and probably unscientific.
The tank I can use is set up with a thermo-coupler, remote sensor... and a manual way to move items up and down in the tank to control how fast it cools and warms the items back up.
The max cold temp in this thing is something like -360 F to -385 F.
I'm told it could take about 5 to 7 hours to draw the heat out of normal sized power and preamp vacuum tubes by pure radiation and cooling through the pins... the idea is to not dip them in the nitrogen but hold them up in the super cooled air.

I think I might try a handful of cheap ass tubes Chinese, NOS tubes and some good reissue tubes from current suppliers/vendors and just try them out with some local players and not tell them what's up.

One thing is for sure... even if they do sound better, different, or last longer.... you'd have to be a complete mental case nut job or total idiot to buy a cryo-treated NOS 12AX7 for $200 to $350.

[Enzo]

And to be scientific, you can;t preselect them. You need a batch of same-type tubes, split into two groups: treated and untreated. test each the same. When they preselect tubes for superior characteristics and THEN cryo them, I don;t doubt they sound better than non-preselected tubes.

[Chuck H]

Bruce, kudos for the scientific method as opposed to accepting faith or opinions one way or the other. And FYI you can cryo steel at any time and get SOME benefits. But the cryo process is usually incorporated into a more complex heat treatement regimen for maximum results. Since you have access to a cryo service you might consider taking all your cutlery over there. There are very real benefits to cryo for most tool steels.

I dabble in knifemaking. Not so much metalurgy but I have done ALOT of reading on the subject of cryo.

As mentioned by the sceintists in our midst, steel that has martenistic properties are the real benifactors of cryogenic treatement. And those benefits are primarily more hardness and toughness (or more harness OR toughness without sacrifices to the other characteristics). Since the materials used in the construction of tubes are not matenistic steels, and tube innards are not performing any function that requires them to chop, pound or cut, I don't see how there could be any benefit whatever. But there is plenty I don't know and there may be some side benefit I am unaware of.

Thats my $.02. I've never bought into it myself. But I can say that I have been tempted to send a few tubes out for cryo just to see. You can get a proper cryo tratement performed on a mass of tubes far cheaper than the cost of cryo treated tubes. So I am very much looking foreward to the results of Bruce's test.

FWIW Bruce, most tool steel MFG's suggest a cryo treatement that lowers the temperature to below -305*F over a period of 12 to 24 hours. Then hold there for 24 hours. Then bring back to room temperature slowly over a period of another 24 hours. This is usually followed by an additional temper. But the extra temper is optional and has marginal benefits. I can't say this would be the same as what you want for tubes. But there you go.

Chuck

[tedmich]

And to be scientific, you can;t preselect them. You need a batch of same-type tubes, split into two groups: treated and untreated. test each the same. When they preselect tubes for superior characteristics and THEN cryo them, I don;t doubt they sound better than non-preselected tubes.

ideally you'll double blind it: two sets of tubes randomly selected and code them with numbers (suitable label tape is here: http://www.fishersci.com/wps/portal/...=&fromSearch=Y

then treat 1/2 and have a third party recode them randomly (ie #1 ->B, #2 ->R etc. and record the "code" and sit on it) then you test the tubes and record your judgments (treated / untreated) and see if you are better than random.

Ideally you would either not treat them, or not see which one is being tested to avoid subtle biases ("I remember the one with the bent pin #3 was treated and it does sound a little better...")

once you reflect on the cost and bother you have gone through to do all this it is VERY difficult to be unbiased, and you gain nothing....except the truth!

[hasserl]

Lot's of discussion of the effect of the cooling on the metals, but what about the glass envelope? The rate of cooling and return to room temp would have to be controlled to prevent thermal shock induced failure of the envelope. But what effect would the cryo treatment have on the amorphous structure of the glass? Would it weaken it, or possibly even strengthen it? Glass does not have a crystaline structure, but exposing it to temperature changes does effect the strength; all glass goes thru an anealing process where it is heated to relieve internal stresses then brought back down to room temp; and then there is tempered glass that is also subjected to heating and cooling. So what effect does super cooling have on it? And would it lead to lower reliability (easily cracked envelopes or loss of sealing around the pins)?

[Steve Conner]

I heard that the Kopi Luwak guys
http://en.wikipedia.org/wiki/Kopi_Luwak

are bringing out a new range of tubes that have been passed through a civet cat. I'm saving my money for that.

[Chuck H]

I've been doing that myself for years. You have to swallow the tubes head down. Pins down is a bitch.

Seriously though, it sounds like a crappy idea.

Chuck

[Enzo]

But not really bullshit, after all.

[tubeswell]

I'm gonna get me a BB gun cos one of those pesky cats shat on my backdoor mat last night and it was a brand new mat. Nothin' worse than cat shit on your back door mat

[Chuck H]

Hey, there could be a free cup of joe in the deal

Chuck