tube markings

[ampcabinets]

   x

[stingray_65]

you mean the "OTK 2" ?

[navdave]

Yep those are made in the same Russian factory as Sovtek. Mike Mathews (new sensor) bought the rights to all the old stuff.
The Tung-Sol preamp tubes their making are great.

[PRR]

Mullard and Tung-Sol are just trademarks today. Svetlana is murky. And Mike owns many of them.

A lot of guitar-good power tubes come from Mike's factory (bought after the fall of the USSR).

Does he sell the identical tubes under different brands? Or does he have several sets of stampers? Or different vacuum standards? The two you linked do seem to be different stampers, also bases. That may or may not mean they are significantly different.

Mike's tubes seem to be sturdy workhorses; he has enough production and marketing experience to know that's important. Whether any particular tube has "magic mojo", or the character was ironed-out in favor of a smooth consistent (boring) reliability, I dunno.