I recently visited a site that offers cryogenically frozen tubes for sale. Now, I'm open-minded (sometimes) and don't wish to malign any vendors using this process, nor devotees of these newly minted "gems," apparently having been Mullards, Teles, BBs, and RCAs "in the rough" prior. My only problem is that every part of this process seems counter-intuitive. Visualizing the expansion and contraction of bridges caused by relatively minor temp. swings raises my 1st concern; wouldn't the freezing to -320 and heating to +350 (720 degree swing) cause a loss of all-important vacuum due to the different expansion and contractions of steel and glass? Furthermore, wouldn't the carefully cured cathode emission surface be cracked and fissured like asphalt in an earthquake? This would most surely improve emission and therefore sound quality on the short term; such distortion and disruption would only negate perhaps the greatest quality of these pre-1970 tubes, namely the long, carefully controlled curing of the cathode to ensure slow, even dispersal with adeqate emission over tens of thousands of hours(loosely paraphrased from the Mullard Valve Standards refernce Tome)? Is this a case of (I can't help myself) tubes before swine? I'm perfectly willing to listen to opinions, and possibly even be swayed to the point of purchase of a pair of "improved" Telefunken 12AX7s. With no REAL evidence or theory behind this, however, it appears no more essential or helpful than smearing sacrficial blood on the tubes under a full moon while chanting and burning incense. Oh, and about removing the pin oxidation, another stated benefit, I find that fine emery cloth works perfectly, thank you very much. Now if you'll excuse me I need to throw the I Ching and locate a Maiden Pure. There's a full moon coming.
I have an access to liquid Nitrogen. I would be willing to try it out, but I need protocol for this procedure.
Anybody knows anything about it?
I'd really like to try this at home, but I think the slow cool down, long hold, and slow warm up are important. I don't have any idea how this may be accomplished. Anybody have any info, web sites, or books on how an effective cryo-chamber could be constructed, that would incorporate some type of temperature/time control?
Thanks to all for the input; as I thought it is a controversial subject. If only I had $$$ to see for myself. Psychoacoustics plays a part I'm sure, but several well stated points about cryogenics and metallurgy are well taken. I'm more concerned about the more delicate componenets, esp. the semi-powdery cathode emission material. Perhaps the changes to this all-imortant surface caused the harshness reported w/ the VTs (by Jack G., I believe) I think I'll hold off, as the people who have actually tried them do not seem to have been impressed. Thank you again for your consideration, Chris. p.s. I got my CV4085/EF86 GEC tubes from Ken Chait via two-day UPS. They are, to say the least, "all that." They seem to meld the airy, shimmering treble of a Bugle Boy with the harmonic richness and layered, 3D soundstaging of my 1964 Calvert labled Mullards. All this plus BASS! In my Eico Hf60s they bring the Gold Lion KT77s to their full potential, seeming to pull a warm, rounded, effortless bottom octave out of nowhere. In this particular app., they knock down Telefunkens, long and short plate Mullards, Bugle Boys and (no surprise) Teslas. Amazingly, the Teslas really are not too bad; they absolutely SLAUGHTER Svetlanas, but with the real deal Mullard at 20-25, and even the CV4085 at $35, life is just too short. Thanks again.
Being basically a pretty conservative type when it comes to all this pseudo audiophile science, I will err on the side of the massive number of engineers/scientists that developed the tubes in question. This was done when tube mfg. what at its highest, when a massive amount of 'brain power' was devoted to the subject, and the applications were far more critical than audio application. Does it improve performance, maybe it does, maybe it doesn't. But cryogenic processes were know way back when.
I find it interesting that we start comparing the relative benefits to tubes because it works in gun barrels, machine tools, car parts, etc. Besides the fact that they all employ 'metal parts' I don't see any sort of common element. The dynamics of metal structure within tubes is vastly more complex than any of the mentioned items.
Maybe it does produce a benefit. Can someone show me scientific evidence of its benefits and effects on long term stability and life expectancy? I am going to guess no, since the days of real scientific study of tubes is long gone, at least in the West and also in the case of most of the tubes that we are discussing. In the end, sounds like another one of those audio 'snake oil' things IMHO. I am not going to risk damaging my valuable and rare NOS tubes for some perceived benefit. When someone can present some solid scientific evidence that is peered reviewed I would be willing to revisit my current position. The real NOS jewels are just too darn expensive anymore. Maybe I would be willing to give it a try on common old Svetlana/Sovtek type stuff.
I have Cryo Vac 5687 Raytheons as drivers for 300Bs in a PSE amp. They are simply astounding in the improvement they bring to the height of a soundstage, pinpoint imaging, and huge dynamic contrasts. They did cost a lot, but I am happy with them and can honestly say they did for me what was advertised. The improvements are very dramatic. I have no commercial interest in promoting them.
That sounds great! I am still going to have to question the long term effect on the tube. Until I can see some scientific evidence my valuable Siemans/Amperex 7308, etc. are not taking the plunge! I have heard many things over the years that produce benefits in the short term, but in long term ended up being a disaster.
I'll talk to Jennifer Nyquist at Jenalabs about cryogenically treating my globe TJ 300B meshies. She's got a liquid nitrogen cryo chamber from Pearl Tubes. She's offered in the past to let me "throw some of your stuff" in with one of her batches. I originally thought about doing my Audio Note DAC PCB.
She was semi-reluctant to do tubes at that time because of the length of time that the tube had to remain in treatment. From what I had gleened, the latent heat in the internal structure can leach out only via conduction through the (small cross sectional area) base connections. This is why it takes a longer time to treat the working parts of the tube.
If I can get her to do it, I'll report back the differences.
I never thought of that, but the long time period makes sense, after all they are vacuum tubes. If you do the treatment with the TJs, please do post, or at least let me know. I'm very interested in the effects on the meshies.
the noise floor is lowered.
due to this or possibly other reasons, the "personality" of the tube seems magnified. I tried the 5751, and it was warmer smoother and more relaxed. I tried the Syl.VT-231s. I find the normal vt-231s to be bright edgey and foward. The cryovac versions were brighter, edgier and IN YOUR FACE. My girlfreind cringed, I winced. I sent them back the next day.
Take home message-if you like the tube, you'll probably like the cryovac-if you don't you'll HATE thecryovac version.
Are they worth the money?
Thats an individual decision.YMMV
They do seem marginally quieter, maybe.
They are a little more etched, and as inputs on an old C-J amp I like what they do, as those nice old soft-sounding amps can use a little sparkle.
I've tried two cryoed tubes and both seem to magnify whatever the basic personality of the tubes is - almost to the point of charactature. To be avoided at all costs IMO - especially at the prices involved. But it most definitely does something to the tube.
----Seventy YEARS of design show
that vaccuum-tubes run best when hot, with ambient
air used to circulate away any excess heat---
however, COLD would be good for s.s. devices,
such as putting your PC's memory- storage chips
in a kitchen freezer,with a cable
connecting it to the PC would most likely
improve its performance...
Cryogenics has been known to stabilize the micro and macro geometry of metal since before there were vacuum tubes. It has known benefits as the standard treatment in manufacture of precision gage, "Do-All", or "Jo"hanson blocks used as the Standard for accurate comparative measurement since the 1880s.
Henry Ford considered the then produced in Sweden Jo Blocks to be of such a high priority to national security during WWI that he instituted domestic cyrogenics research.
Cryogenics is used extensively in other industries to improve metals characteristics. No pixie dust hear. People are treating engine parts, cutting tools, etc. for real measureable benefits.
My understanding is that are also real measureable benefits of before and after cryo treatment of tubes. The two areas I know of are microphonics and noise improvements. From what I'm told, it took a good while to perfect the process, and in fact the temperature treatment process takes many days due to the slow change needed.
If you have questions about it, why not ask the business directly?
Thanks, but vendors seemly oddly bent on vending. Your point about metallurgy is well taken, however.
I toured the Pearl facilty couple times and have spent a lot of time talking to Bill Perkins. He has invested much R&D effort developing methods to control tube microphonics, and has what I would call an entire system, cryogenic treatment is just one part. Bill is not a voodoo or fairly dust type of person. He has an incredible electronics lab full of test gear that is used to document everthing he does. If you download and read his stuff on tube cooling, I think you'll see where he is coming from. A big part of the reason these tubes are more expensive is they are graded and sorted for noise and microphonics. He also hangs out on joe net if you want to get him there.
I too am very interested in this. There seems to be a couple of approaches to cryogenics. One is a home-brew method using dry ice and acetone, and a professional method using liquid nitrogen. The professional method I looked into takes several days. The cool down is very gradual over a long period of time, then the object is held at the maximum low for 24 hours, then very gradually back up to room temperature. I think this answers your concerns about the differing expansion rates of the materials in the tubes, and possibly cracking of the cathode emission surface. I don't know how this process effects the sonics of tubes, but sure would like to know. Of course I have no idea how this effects the longevity of the tubes. There is some speculation that this process would increase the life of the tubes by relieving stress in the metal structures. I know this has a beneficial effect on metal parts that are subject to extreme conditions (they last longer). I have heard that some musicians that play brass instruments, believe this process improves the tone of their instruments. Also some target shooters swear by this treatment for their gun barrels. They claim that the molecules of the metal form a more crystalline structure and vibrate more consistantly, and as a result are more accurate. However this opinion is far from unanimous among shooters. If anybody has any first hand experience with this process and tubes, I'd sure like to know.
Cna you elaborate on this "home-brew" process? It sounds a little bizare.
Home brew cyrogenics involves liquid nitrogen.
Dry ice is pure BS, as a cryogentic treatment.
Dry ice is very effective. I have done CD's, cables and stuffed pc boards to good benefit. I have also tried the computer controled ramping systems that utilize LN down to -300. Stan Warren described the benefits of dry ice to me and has done some extensive listening tests to like items put through both processes. Call him if you want more info.
..a "cryogenic" treatment. No matter what differences (and I'm not disputing that) you may have heard.
If you need a mechanism to attach to the perceived change in sonics, may I suggest that you find another? Dry ice is not nearly cold enough.
The problem is your have read this and yet have probably no experience to back your claim. Don't knock it until you give it a try.
I doubt if dry ice and acetone would work. Saw it on the tweakers asylum, so thought I'd throw it out there. Didn't know people were using liquid nitrogen at home, yikes! Some folks claimed the dry ice thing helped, but you know about the placebo effect. I would think that not only the temperature, but the very slow controlled approach would be necessary for optimum success. Not sure any of this would really be beneficial, just curious, and trying to keep an open mind.
The proof is in trying it yourself rather than speculate. It worked for me.
Nitro is very common and available. You can buy tanks and nitro from artificial inseminators if you live near where they have dairys or any operation that breeds registered cattle. The bull semen is kept in the tanks and they tell me it would last for hundreds of years. It isn't very expensive, or at least not compared to what you are paying for some of these tubes. It does need to be handled with common sense and care. But it is just a simple immersion and if there is more to cryo than that then you will have to figure that out.
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