So after a week of trying the Sovtek 6H30Pi-EB and Electro Harmonix 6H30Pi as the output driver tubes..
I think the Svetlana is really build around the 6N1P-EV and 6N6P-I tubes. I will have to ask Kim about this. Eventually I returned back to the stock configuration and there is no match. The stock tubes were Voskhod and Novosibirsk respectively. I am finally recognizing the different logos on Russian tubes..
Searching for any impressions and information about the 6N1P-EV and 6N6P-I tubes, I have gotten some insight of the era when these tubes were made. It seems these tubes can sing when the amp is really designed for it. Strong against microphonics, silent operation, militairy spec and long life. They are dirt cheap and have good availability. The NOS 6DJ8/6922 variants can vary.
Going the NOS route with 6DJ8/6922 tubes for the input stage can be quite a gamble. It is pricey and I am not sure if it gives a sonic improvement with the Svetlana, aside from your preferences. For any future owner of the Svetlana. If you like the amp in its stock configuration right from the start keep it that way.
Part of me really hoped the new tubes would be different or better, along with the excitement that rose as a first tube rolling adventure. On the other hand it just made me appreciate how excellent performing the Svetlana already is! It is a nice amp with Audio Technica woodies.
- Editied my original post..
Cool, thanks for being the guinea pig for me! I know as audiophiles we are conditioned to want to roll tubes, and to automatically expect an improvement when buying some rare gem of a tube. But thankfully that isn't always the best way to go - sometimes stock tubes are quite nice!