Today we have a story for you all. It's about 'em tubes. Yes, again. But please bare with us, this tale really is special. You'll see soon enough...
The (5670) electron valve. It matters. - Part 1/3
Every audio aficionado likes 'em Electron Valves and for a number of reasons. The two most obvious ones are their influence on the sound itself and highly appealing aesthetics. Some of you might dislike the look of glowing glass and since this matter is highly subjective one, we won't focus on it. The rest though, well, that's a completely different story.
Our latest headphone amplifier - the Pro iCan - is loaded with a pair of GE5670 JAN double triodes. OK, there's a ton of valves out there. Therefore this question is in order: why we use this one specific type from this specific manufacturer? Now that's a story to be told. Here we go then.
Behold the WE396A double triode by Western Electric. These small critters were introduced in 1946 and shortly replaced by their 6922 variants. The former is the pinnacle, almost unfindable these days. The scenario isn't that grimm when it comes to the latter type. But as it turned out, there is one sonically as good model and made to very strict specifications - the GE JAN 5670 NOS type. It was under the radar of the audiophiles' scope for many years.
GE stands for General Electric manufacturer, which is self-explanatory. Said company was responsible for Electron Valves production for decades and is well-known for the quality of its products.
Moving on, JAN is the service branch of the US Armed forces and said three letters stand for Joint Army & Navy. Electron Valves marked as JAN were made for the Army/Navy (the airforce had to have their own naturally) and had to pass the most rigorous testing procedures at that time.
The Russian parallel system was OTK, which means "Отдел технического контроля" or technical control department. Even the Russian system was very decent as one does not wish for Mach 3 Jet Fighters at 100 million ruble a pop to be falling out of the sky on account of poor Electron Valves. This translated into modern money would be ~350 Million USD - the same as the F-22 Raptor today! And yes, it used Electron Valves for a lot of critical electronics.
It packed a targeting Radar so powerful it was a crime to even turn it on except in combat or exercise. It would kill small mammals at several 100 feet (microwaved to death).
Side Note: The Mig-25 Foxbat (a Mach 3+ jetfighter that scared the poop out the USAF at the time and inspired the Clint Eastwood film, ‘Firefox’ was no cheap junk (even if it was not as rad as the Firefox).
Germany/Europe never had an equivalent system, they got either JAN electron valves with US equipment (including export versions) or German Postal electron valves (CCa, C3g, D3a etc.) made in...Germany.
The British Empire had (surprisingly) its own inter-service system for military electron valves, it came into force in 1941. The British generally used civilian electron valves (and later transistors) that were tested and certified for military use. British Military electron valves are identified by the letters CV (Common Valve) and a number.
Generally JAN/OTK marked electron valves are more rugged, have very tight technical parameters and much less variation, yet are at the same time compatible with civilian types. German/European Postal electron valves in general were dedicated designs with the singular exception of the Cca and equally ruggedised. British and Chinese used selected (or not) civilian electron valves for military applications.
Stay tuned, there's more...