Another day, another tube - my friends, for those of you that use valve amplifiers - be you a guitarist, an enthusiast, or an antique radio aficionado - finding newly manufactured tubes is quite the dilemma.
At the moment, the only brand-new tube manufacturers, which are not Soviet-era NOS (New Old Stock) are located in the Russian Federation and the People's Republic of China. Fortunately, importing them is not particularly challenging, as there are plenty of middlemen in neutral territories (Russian tubes may be readily acquired through post-Warsaw-Pact countries, and over the Commonwealth of Independent States) - Chinese ones may be ordered directly, albeit, there are fewer options on the market.
While opening eBay will yield thousands of listings for NOS tubes, Svetlana Electron Devices is one of the only manufacturers (based in the old Reflektor plant in Saratov), currently producing tubes in Russia. There are two American manufacturers which I've found, one based in Newbury Park, California, called Pentalabs. You can find a variety of tubes, albeit at rather high prices.
The other major North American producer is Electro-Harmonix, selling tubes under their EHX family of brands (Tung-Sol included).
Now, our cup runneth over with manufacturers in China - we've got Shuguang and Psvane - both selling tubes under a variety of brands. Although Chinese tubes are manufactured slightly less robustly than Russian tubes, and with less control than American producers, they are excellent, inexpensive, and easily-importable options.
With that being said, I prefer Russian tubes, as they are primarily based on Soviet designs, which were, as mentioned above, built more robustly than their Asian and North American counterparts - for the price, they just can't be beat. Still, I have to say - if running without a budget, American tubes are a wonderful option, with some of the highest tolerances to be found.
Now, my current setup isn't particularly fancy - I'm running a simple, dual-tube amplifier, with Chinese old-stock 6K4 tubes. As they're powered on nearly twenty-four hours a day (courtesy of not having the time to wait for them to heat up), I don't expect for them to last longer than a year - prior, I'd only run them occasionally, and have had the same set for roughly three years at this point.
When they finally burn out, I expect that I will be buying an adapter plate, and opting for a currently-manufactured option.