Tung-Sol 6SN7GTB

I bought a pair of these mostly to see how they compared with my OS JAN Tung Sol 6SN7GTBs. First thing to note is there's a major difference in plate structure: my JAN (Joint Army-Navy) tubes have triangular plates, while the Russian TS tubes are rectangular 'ladder' plates. The mica supports top and bottom seem identical, and the Russian tubes have small dimples in the top of the glass while the originals don't. As for sound, in absolute terms the Russian Tung Sols are very good tubes with a deep and holographic sound stage. Detail is very good and so is bass and midrange. Compared to the originals they seem to have a bit more gain (though that could be age on the originals). The biggest difference is in the treble - the Russian Tung Sols are a bit rolled off compared to the JAN tubes. Not so much to be a deal breaker, but it's noticeable.

Amazing! I bought a used Rogue Tempest II, recently. It came with KT88EH (ok), Sovtek 12ax7 (eh), and no name Chinese 6SN7GT. I was going to replace the smaller tubes first since they were the cheapest and worst, but I decided to go all out on the Black Friday sale. I got the TTS KT88s, TTS 12ax7s (7025), and Tungsol 6SN7GTBs.
I'm too old to spend the time and energy on A-B testing so I switched out all the tubes and fired it up. With nothing more than a warmup the sound difference was like an entire system upgrade. I've been around audio a long time (and I really do not like the general direction the industry has gone) and I was a professional classical musician for many years. I would not have though that much improvement could come from a moderately priced tube upgrade.
The sound is better in every aspect. And not by a little bit.
Detail vs warmth? Don't settle!
If the detail is not revealing better music, then what is it really doing?

Bought the Tung-Sol to replace the factory Shuguang tube on my Darkvoice 336SE. The Tung-Sol completely changed the sound! It sounded so rich and open. This really makes music.
Unfortunately, the dreaded left channel hum came along for the ride. It is not loud, but can be heard without playing music. The right channel is completed silent. This is well documented issue with the 336SE and the solution seems to be to allow the tube to burn-in for at least 72 hours. I am going to let the amp run for 3 days straight.

I installed this tube in each of a pair of HF-60 amplifier. In this amp, this tube is used as a phase splitter. Sounds beautiful, no difference to my hears with the vintage one. Solid construction and it looks nice with the brown base.