Finally getting around to a bit of rolling
So, I'm just getting around to tube rolling. I still haven't settled my DAC situation yet, so that's a work-in-progress. In the meantime, I feel I've learned the stock flavor with the Ulyanov 6C33C's and the Tung-Sol 6SL7's that Craig ships the unit with.
On Tuesday, I received the Svetlana 6C33C-B's from Nikolay on eBay. They arrived in their original packaging, and I've left them burning in overnight with the stock Tung-Sol 6SL7's. Tried them tonight and didn't quite dig 'em. Felt they were a bit soft, recessed, and distant. Listened to them most of the night, and still wasn't digging them. Now, I know that the 6C33C's take about 100 hours to burn-in... and during the time, they change quite a bit in measured characteristics, so I'll reserve final judgment 'til next week.
Today, I got in the Brimar 6SL7/CV1985 and Sylvania 6SL7/VT229 from Upscale Audio, where they've been apparently screened for balance and have some level of burn-in. Tried the Sylvania VT229 with the stock Ulyanov 6C33C's for an hour and found them textured but rolled off at the top end. I swapped it out for the Brimar CV1985 and found that it presented a strong midrange with plenty of texture and detail... more so than even the stock setup.
Now, here's the kicker. I was curious as to how the Brimar would sound with the Svetlana 6C33C's. Verdict? I believe I found a nice combo for me and my HD580's for now—powerful, extended bass and smooth (a little soft?) highs with a textured, yet articulate midrange. I'm REALLY enjoying this combo right now as I write this. It's a pleasant presentation, albeit not one I'd call crisp and detailed.
What did I learn in this brief exercise? That it isn't just about swapping out one set of tubes. It seems that it's the combo and interaction between the 6C33C's and the 6SL7's that synergistically produce the audio presentation at the end of the chain.
With all these different characteristics, I must admit that they must be various levels of sonic coloration. I haven't measured anything on a scope or freq analyzer to sort through it all, so these initial impressions are just based on casual listening and based on my subjective interpretation of likes and dislikes.
I believe I will live with the Svetlana+Brimar combo setup for a week or so to really get to know it.
I know Craig takes a lot of care in matching up the tubes and burning them in before they ship. Which is why I'm leery about going down this rolling process when I'm picking up NOS tubes from a Ukrainian dealer—no screening process. I'm also not fond of the fact that if any of the tubes go out, that I risk the sonic character changing if I don't get the some tubes with the same characteristics as I had before. Ah well.... not that big of a deal in the greater scheme of things... (just some rambling thoughts on the matter...)