"Why do these vintage 45 year old tubes look old???"
By: Brent Jesse, www.audiotubes.com
NOS tubes: a phrase which will live in infamy. A phrase which has become nearly as meaningless as "world class", "high fidelity" and "factory fresh". There seems to be a mystique about tubes to begin with, as we now have nearly two generations of audiophiles who grew up knowing nothing about tubes. These children of the solid-state revolution perhaps are just now becoming acquainted with these strange glowing glass bottles---heck, not even real glass bottles are glass anymore! To fill one with a light bulb filament, some wire mesh, a little can of metal, and then suck out all the air, and expect it to make sound is like some strange throwback to Victorian times when people were recording sounds on wax and tinfoil. But the retro-cool fascination is there as tube radios and hi-fi systems are making a roaring comeback. Dusty old tube lore is being reprinted, and tube amp schematics from the 1940s are being sought out, built exactly to specification, and sanctified by tube gurus worldwide. With this rebirth comes the hoary holy grail of every tube aficionado: the NOS tube.
So what's a NOS anyway? This is the acronym for "New Old Stock". New old stock is not by any means just a tube catchphrase. It is mainly a retailer's term for any stocked item which is either A: out of production; B: discontinued from the current line of product; C: has been sitting on a stockroom or warehouse shelf for some time; or D: any combination of the above. The only constant here is that the product is unused. Actually, Unused Old Stock is a better term, but trying to say the word "UOS" proved to be too difficult! New Old Stock can be found in everything from computer drives to Ford Model T ignition coils. It fits well in the tube world, since tubes were made by the billions up through the 1970s, and the solid-state changeover took place rather rapidly. Many of these billions of tubes suddenly found they were sitting on a shelf, certainly no longer NEW, but definately OLD STOCK that no customer had ever purchased. TV repairmen put away their tube caddies seemingly overnight, still stuffed with 6BK4Cs, 12AX7s, and 6DW4s among millions of others. TV sets, radios, hi-fis, and industrial equipment embraced the new silicon replacements for tubes practically overnight, and tubes went the way of the vinyl LP record just as quickly.
I can't help but launch into a NOS tube buying "experience" I had recently, so please bear with me. I was at a garage sale recently, which was actually in a large barn with more than a few leaks in the roof. Under piles of glass jars full of screws I found box after damp box of globe shape tubes, mostly RCA and Silvertone 4-pin base types. A number of these were UX245 and UX226, both sought after antique tubes today, which audiophiles are building amps around. Some of the boxes fell apart at the touch. I bought those and left my card with the seller, who indicated he had more at home. I later examined these tubes and found them all to be intact, and all tested as NOS--in other words the emission pinned the meter of an emission tester and read as high as any similar NOS tube on my transconductance tester. However, some of the boxes had been partially chewed on my mice, mice chewings were everywhere, and others were water damaged. In addition, mouse feces were found in some of the boxes. Needless to say, these tubes did not look shiny and new, and the pins on most had darkened. I had a cleaning job to do. Some of these were destined to be sold as "New Old Stock White Box" because in their unclean state they were truly "Nasty Old Stuff".
The guy called me about two weeks later, and offered me the rest of the tubes he had dug up. I went over and found the last remains of what, he said, had once been a proud radio repair shop in Chicago over 50 years ago. There were glass coffee jars full of wax capacitors (remember when coffee--and I don't mean instant coffee--came ground in glass jars? I don't!) more globe tubes, a Western Electric "tennis ball" tube (now in my collection) and a number of 1940s vintage tubes in kind of ratty boxes. I bought the whole works, and again found that the mouse turds were included free of charge. Again, I have a bunch of great NOS tubes that don't look, well, very NOSey. The preceding is a true story, only the names have been changed to protect those who became "unclean" by touching "Nasty Old Stuff".
Do NOS tubes have dark pins? Most of them do. The only NOS tubes that retained bright pins are those that were sealed in the original box, and then stored inside of a plastic container, or possibly in a larger box in a temperature and humidity controlled environment. Not many tubes received this kind of loving care 40 years ago. Only gold pins should remain bright no matter what the storage conditions. Most pins of miniature tubes, being usually made of a copper alloy, will darken rather like an old penny. This does not affect the operation of the tube. If you are a purist, cleaning the pins with a good grade of contact cleaner with a Q-tip is a good idea. Cramolin DeOxIt is an excellent product for this use. Heavy encrustation will create noise and of course should be cleaned. I don't sell any tubes in this condition as all of my tubes have been inspected and cleaned where necessary. I know of some tube purists who sandblast the pins clean, and this is fine too, as long as any remaining grit is cleaned away by contact cleaner afterward. For most of us, a gentle brushing with a fine wire brush followed by contact cleaner will rid the pins of any Nasty Old Stuff. Don't freak about dark pins. These tubes are antiques, and have not spent their time in airtight containers! Cleaning the pins (unlike cleaning rare coins!) will not decrease their value, and your hi-fi will thank you for the increased contact and socket lubrication.
Real NOS tubes have labels that don't wipe off, right? WRONG!! Please don't be taken in by big dealers who sell "NOS Mullard and Telefunken" tubes by the dozens with incredibly clear, perfect labels. What do these poor sucker buyers think when they plug in the tubes and they sound like CRAP? "I must have gotten a bad one, but it looks perfectly new and clean, so it must be a fluke". WRONG AGAIN!! Some people who claim to sell NOS tubes by these vintage European makers are actually selling counterfeit tubes! Hey, if there is big money to be made, making bogus Telefunken tubes is less likely to attract the FBI than making fake $20 bills. I have personally gotten taken in by some of the 6DJ8 Telefunken fakes. They look just like the real thing, complete with the diamond mark (fuzzy and indistinct, but it was there) on the bottom glass. The labels on these were perfect. They were also baked on enamel paint which would not wash or scratch off. The tubes are actually made in China, and deliberate copies of Telefunken tubes. The Mullard fakes are usually late vintage Brimar made tubes that have been relabeled as early shield logo or BVA logo Mullards. The GENUINE Nasty Old Stuff Telefunken and Mullards usually have some of the label smudged, smeared, missing or blotchy. Very rare are those tubes still sealed in their boxes with even the cellophane wrap intact! These real labels used a chalky flat white paint, never shiny like baked enamel. Just rubbing in the box can wipe off some of the label. RCA and Amperex used the same paint, and not until the late 1970s did both of these companies switch to the shiny orange baked enamel label which was harder to wipe off. RCA used it on their new logo, and Amperex used it on later versions of the world logo. So how do these big time tube dudes come upon dozens of perfect labelled NOS tubes? The secret is: they don't find them any more often than I do! I rarely find perfect label NOS tubes, and when I do I brag it up and down the webpage! These dudes have either unwittingly (or knowingly!) purchased a bunch of these perfect looking fakes---which in this case are truly Nasty Old Stuff---or maybe they should be Nasty New Stuff.
Last myth debunked for now: real NOS tubes should be able to be matched to within 1 percent or so of each other. HA! I bet many standard grade tubes couldn't be matched that close even when they were new 40 years ago! Really, folks, the only close match NOS tubes I have ever had were some batches of 6V6GT and 12AX7 tubes that were in job boxes. That's right, the Nasty Old Stuff in the dusty ole egg carton and the tubes don't even have the dang original box! These really fine tubes all had the same date code and were possibly even made on the same day, certainly all on the same production line. Therefore the chances of them matching well were very good. Nearly all matched around 2 percent or better. Most NOS tubes, made in different years, different factories, different production lines, are going to vary. Five percent is doing really good for a match of vintage NOS tubes. Most amplifiers that are designed correctly should be able to operate just fine with even a 25 percent or greater mismatch, provided the bias is set correctly. Please spare me the heated e-mails over this comment, you are entitled to your own opinion. If I don't have many tubes in stock, I will not offer matching for those tubes, since the match will not be close. This does not mean the tubes are Nasty Old Stuff or used, only that I want to be honest and not promise a match when I can't really do it with the stock on hand.
So what is a NOS? New Old Stock or Nasty Old Stuff? Sometimes both. The secret is to either get to know what is available, and what to expect from most of the NOS tubes you can dig up these days, and then go out and find your treasure, or find a tube guru you can trust and purchase your NOS tubes from them. If digging through boxes of dusty tubes at a hamfest is part of the fun, then you will quickly get to know just how nasty some of these vintage tubes can be. You will also find some vintage rarities here that you will find nowhere else, but you have to get down and dirty to dig them up. If scrounging is not your bag, then get a tube guru who sells the real things and does the scrounging for you. Whomever you choose, make sure they have a solid guarantee, and make sure they can make honest judgments about your system and what tubes may be best for you. Above all, enjoy the music! Finding great NOS tubes is the doorway to great music. Don't worry so much about how they look, rather pay attention to how they sound. If it sounds good, then it IS good!