Tu-be or not Tu-be
Questions and Answers on New Old Stock Tubes


Part 1 - N.O.S. Basics


I suppose it was inevitable.

After months of planning, budgeting, and listening, I had finally secured the last remaining component in a carefully plotted upgrade path for my audio system. Out went a cheap but still decent sounding NAD preamp, and in came the unbelievably cool Cary SLP-94. This occasion was indeed momentous as it marked the debut of the tube in my listening room. Never before had my system sounded so alive- the soundstage widened and extended seemingly through my back wall, imaging improved ten-fold, and the sounds coming from the illusory instruments between my speakers acquired an amazing kind of holographic glow. I played record after record, CD after CD, marveling at the staggering sonic beauty of the music emanating from my speakers.

Predictably, as pleased as I was with the sound of the Cary, something kept telling me that this little gem had even more to offer. After a brief, all too familiar internal struggle, I gave in to my audiophilistic urges and went in search of ways to extract every drop of sonic performance from this retro-chic construction of metal and glass.

The tubes seemed the logical place to start. The Cary-branded 12au7's used in the line stage and 12ax7's employed by the phono stage were both manufactured in China. Word seemed mixed on the sonic attributes of Chinese tubes, so I started looking around for alternatives.

I quickly discovered that today's tube consumer faces some interesting choices when making a tube-buying decision. He can buy new tubes manufactured in China or several former Eastern-Bloc nations, he can buy used tubes pulled out of electronic gear from yesteryear, or he can delve into the murky middle-ground known as "new old stock". It was during the course of my new old stock tube explorations that I met Kevin Deal, an individual familiar to many frequenting the newsgroup.

In the audio equipment business since his college days back in the late 1970's, Kevin Deal got his start in the high end while working in a HiFi store that sold tubes. At that time, solid state was "the thing" and tubes weren't so much as an afterthought with most manufacturers of audio gear. After a brief flirtation of his own with solid state gear, Kevin's interests steadily migrated toward tube-based audio products.

As Kevin began to amass his collection of tubes and tube-powered amplification, he realized that certain tubes manufactured by certain companies sounded a whole lot better than those built by others. Inspired by this revelation, Kevin acquired a wide variety of tubes from a host of different manufacturers and began experimenting to find out what sounded best in his own equipment. Also curious about why certain tubes looked absolutely identical yet bore different brand names, he began his extensive research into the internal structure of certain tubes, compiling information about factory codes, batch codes, and date codes for many companies across North America and Europe.

During the course of his ongoing search for unique and exotic audio tubes, Kevin uncovered an opportunity to buy the entire tube inventory from a company called Olson Electronics, which had operated a chain of stores similar to Radio Shack. This large lot of vintage tubes had been sitting in a warehouse, undisturbed and unnoticed, for about 20 years. Recognizing this unique situation, Kevin bought the entire stock and suddenly found himself in the N.O.S. tube business. About this time, he had also started his own high end retail business, Upscale Audio, which provided him with the perfect opportunity to experiment with a wide variety of N.O.S tubes in much of today's most popular tube gear.

I recently had the opportunity to sit down for a chat with Kevin and discovered that there's much more to effectively tubing a piece of audio gear than I had previously been aware…

Part 1- N.O.S. Basics

SoundStage!: Simply put, Kevin, what is a new old stock (N.O.S.) tube?

Kevin Deal: Well, basically a new old stock tube is an unused tube no longer in production.

Where do they come from, typically?

That depends on what you mean … do you mean originally where they come from or where do they come from today?

Let's start with original origin…

Originally, when most people refer to new old stock tubes, they are talking about tubes that were manufactured up through the 1970's by some of the leading electronics companies in the world. In the U.S., tubes were manufactured by companies like Amperex, RCA, GE, Tung-Sol, and Sylvania (Philips ECG). Siemens, Telefunken, and Valvo (Philips) made tubes in Germany. English companies manufacturing tubes included Genelex/M.O. Valve, Mullard, Brimar, and Thorn AEI Radio Valves, who made tubes bearing Ediswan and Mazda brand names. Some spectacular audio tubes were also produced in France by Mazda and Dario, which made tubes looking remarkably like those manufactured by NV Philips of Holland. Holland was also a real tube hotbed in the 50's and 60's- the Dutch company Philips manufactured incredible tubes bearing Amperex, Philips, Miliwatt, Valvo, Adzam, and Mullard logos. I mean, if you were to think of a company that was the "Microsoft" of the tube business, it would probably be Philips-Holland. They were just so huge, owned so many companies, and were responsible for a lot of designs that were used in audio today

Do any of those companies still make tubes?

Not really. The only current tube manufacturing that relates to our business is going on in countries like China, Slovakia, Russia, and in what was once Yugoslavia. Not much in the way of tube manufacturing is going on in the U.S. right now, though that is changing. With the re-birth of Western Electric and the recent purchase of an RCA tube plant, things are looking up for domestic tube production.

What happened to all of the old-time tube manufacturers?

It (tubes) just became a dead business with the advent of transistors- it was no longer cost-effective for these companies to continue making tubes. Many companies went to cheaper labor markets like Japan and Eastern Block countries to have tubes made, then got out altogether.

If you think about it, back in the 60's, a 6DJ8 would have cost maybe $4.00 and the major companies were making hundreds of thousands of them of them. Adjusting that for inflation 5% a year, a 6DJ8 today would cost $20.00 at retail today. We get them from overseas for a lot less than that. Presently, there are just not enough tubes being sold to cover the manufacturing expense in Western countries.

Is the new old stock tube that's, let's say, been sitting in a dusty warehouse for 30, 40, or 50 years as good today as it was originally?


So tubes don't generally age?

No, because the glass sealing techniques perfected long ago have been in use for years and years. The one thing that can happen is that with larger power tubes- sometimes they can become a little bit gassy just sitting on a shelf, but usually that will burn off and without creating a problem. And the pins get grungy.

Why should anyone consider going to the time and expense to satisfy their tube requirements with new old stock tubes as opposed to the ones that are manufactured today?

There are several reasons. First, they allow people to fine tune their systems in a ways not offered by today's tubes. Second, the higher quality N.O.S. tubes can potentially last a lot longer than modern tubes. Used properly, they offer the user the ability to substantially improve the sound of his system, sometimes equal to the level of a pre or power amp upgrade.

How are new old stock tubes different from the typical tube manufactured today?

You have to think about what was going on in the 1950's … the cold war was in full swing and everyone was using tubes. In those days, there was much more tube manufacturing going on and the quality of many of the raw materials used in tube manufacture was much better.

When I think about a Mullard tube made in the 50s, I think about some old British dude with bushy gray eyebrows. When I consider the RCA's, I picture an American engineer with a crew cut. Tubes were "it" and I think there was a lot of competition to make a high quality tube. I think that there is still some of that same competitive spirit today, but the countries currently manufacturing tubes face obstacles perhaps not encountered by Western tube manufacturers. Some of these countries are having a tough time supplying the people with toilet paper and food, let alone high quality raw materials for electron tube production…

How do modern tubes compare to new old stock tubes, generally speaking, in terms of reliability and longevity?

I don't think that they are quite as reliable, but I think that they're getting better. Looking at the price that you have to pay in today's dollars for a tube compared to years ago, I think that many modern tubes are a bargain.

A good example is the Russian 6922, which seems to be a pretty hot tube in manufacturing right now. This tube is actually pretty good. It is quiet- even quieter than a lot of new old stock tubes. Also, it doesn't have sensitivity to microphonics or vibration whereas a lot of new old stock 6DJ8 types do. On the downside, they seem to age a little weird, so as far as longevity goes, I'm not really comfortable in saying that they are the last word there because they're not. They don't seem to last as long as some of the better quality new old stock stuff, which I believe can be attributed to the purity of the raw materials used in the manufacture of the tubes. But while they can sound good, they really can't compare to the best old production 6DJ8s.

If new old stock tubes are generally the better option, why do high-end manufacturers typically supply Chinese or Russian tubes with their products?

Predictable availability, mostly. You can't design a component and then voice it for a tube that you may not be able to purchase. There's just not enough new old stock for manufacturers to know that they'd have these tubes in stock for shipment with their product and to offer as replacements to their customers when it's time to re-tube. It is also a question of cost. How much money can the manufacturer spend fitting their products with rare, sometimes expensive, N.O.S. tubes? I recently started to supply one of the largest guitar amp manufacturers in the world with small signal tubes- they buy thousands every month. For those guys, their concern was a nickel or a dime cost difference per tube. While high-end audio is in a somewhat different situation, manufacturers still have to consider their bottom line.

How do modern tubes sound, to your ears, when compared to N.O.S.?

It depends on the tube. Most feel that Chinese 12AX7’s and KT88’s are somewhat bright, hard, and two-dimensional. Frankly, I think the EL-34’s that come in the Jolida amps sound OK. Russian tubes are OK. I would like to see more from Yugoslavia. I like the latest version of the KT90. They’re very civilized, good bass, sweet. The earlier versions were kind of like an overgrown 12 year old kid on steroids with not enough to do. But they still can’t compare to the original MO Valve KT88

.....continued in Part 2 - Sonic Characteristics of N.O.S. Tubes