Wow!
Where to start.
Unlike many tubes designed for products that are long discontinued, the guitar players of the world have maintained a market demand for the tubes used in their guitar amplifiers. As a result, many of them are still in production.
The 6L6GC is one of those. Tubes that are still made in Russia and China are pretty much the only newly-made stock to choose from.
One oddity is with the name "Svetlana". It's a company in Petersburg Russia, who sold the rights to their name in the USA to a guy named Mike Matthews. He runs a company in Long Island that owns a factory in Saratov Russia. They bought production-line equipment from closed USA factories and moved it all to Saratov. He makes what he calls "re-issue" tubes with the names Tung-Sol and, of course, "Svetlana". And that's what is odd. Any tube you buy in the USA with that name on it was not made by Svetlana in Petersburg, but in Mike's factory in Saratov.
If you want a genuine Svetlana-made 6L6GC, it will have the name "SED", for "Svetlana Electron Devices", or what they used to call "Winged C", since that's what their logo looks like, the letter "C" inside a circle with wings on each side.
Go figure.
What all that long-winded story leads up to is that we have had really good results with the Svetlana MADE 6L6GC. We get them from CE Distributing,
www.cedist.comBut you have to sign up before the site will let you see any prices.
There may be some chinese-made tubes that are okay, but I don't have any direct experience to pass on with those. Mostly I have avoided chinese audio tubes, after having quality problems with some of them.
As for old-stock tubes, the GE 6L6GC or 7581A (same tube, different test requirements) were probably the best of all time for the D201 that I remember. But the GE, RCA and Sylvania (Phillips ECG) factories all closed years ago, so finding old stock becomes a treasure hunt.
Just remember that the name on a cardboard carton, or painted onto the side of the tube doesn't really tell you who made the tube. Only tells you who packaged and sold it.
Tubes leave the factory assembly line blank, with only the type number printed on them. They're packed into trays of twelve dozen, and then sent to a sales company. THOSE are the people who paint a name onto the glass, and pack them into individual retail cartons.
Naturally, each of the old USA factories was owned by a bigger corporation, who would also own a sales company. GE tubes would ship to the GE Sales division to be marked and packaged.
Until they ran out of a particular type. If the GE factory was not scheduled for another production run of the type they're out of, the sales division would buy them in bulk wherever they could. The name "GE" would get printed on tubes from Korea, Japan or the USSR if that was what they could buy on the spot market in bulk.
The sales companies' incentive was to fill orders, no matter how they went about obtaining the bulk products that they sold.
All the name brands would do this. A tube that said "RCA" on the carton might have been made anywhere, not necessarily in Camden New Jersey.
Somebody (else) should post a YouTube video showing how to identify who made a tube, no matter what name is printed on it. Haven't seen that video yet. Don't hold your breath waiting for me to do it.
But that's the short version.
Just one more opinion. Stay away from any 6L6GC that says "Made in USSR". Had some bad experiences with those. Not "Russia", but "USSR". Can't be many of those still in circulation, but those had a bad habit of going nuclear when used in the D201 audio socket.
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