6SN7 tube question

There are three kinds of 6SN7s: GTs, GTAs and GTBs. If the circuit needs one of the latter two and you have been installing GTs, they won't last very long. GTs don't handle as much voltage.

We've been recommending Andy for decades- he is an excellent source.

Ralph (Atmasphere) beat me to it, as I was just about to post the same comment. The GTAs and GTBs are rated to handle considerably higher plate voltages and power dissipations than the GTs.

But be aware that there are some current production (not vintage) tubes identified as 6SN7s, with no suffix, which meet GTB specs, at least supposedly.

Regarding the original question, I would go for matched/balanced/low noise/etc., as that could very conceivably make a difference.

Also, FWIW, I've been very pleased with ca. 1950s Sylvania 6SN7GTBs in my amp, which I believe requires GTAs or GTBs.

Best regards,
-- Al

Thank you, Al and Ralph. I was actually looking at the Sylvania tubes, but this particular era looks a little bit out of my budget. Circa 1970s is very reasonably priced, on the other hand, and I'd think probably better than any new stuff on the market.

I bought a pair of GE 6sn7gtb's for around 50 dollars that sound very good from top to bottom. They didn't take long to break in and are an excellent value. I didn't buy from Andy.

There is a lot of lore built up around the various brands and types of 6SN7s. Most of all, if your Rogue came with GTA or GTB types, stick with either one of those types. (They have the same max plate voltage of 450V, whereas the GT types are only recommended for up to 275VDC, if my memory serves.) The vendor you asked about seems to be well thought of, so go ahead and spend the extra money, is my advice. But keep in mind that selecting for low noise, balanced triodes (presumably this means that the two triodes in the single glass envelope are balanced vs each other), etc, does not mean that the tubes will necessarily last any longer, which seems to be your main beef. And also keep in mind that 6SN7s are unfortunately prone to go microphonic over time before they die. If you're wearing out tubes prematurely, perhaps Rogue or some competent tech can check the voltages in your unit; maybe there is an issue.