Favorite 300B: Sophia vs KR

I have my new Treasures in the Mactone amp. Have only 15 hours on the tubes but these are big improvement right out of the box over the EH tubes that came with the amp. Everything I read is that I need to be patient with these tubes as they burn in ...good thing they sound so good right away and very listenable as break-in happens.

Would love to do a lineup of 300b designs - set, parallel and push pull and compare sound. I have first and third and will be interested in comparing these two with same tubes with my Audio Note speakers.

Fred Crowder compares the Treasures (with 300 hrs on the clock) and new old stock Western Electric 300Bs in his Audio Note U.K. Balanced Kegon amplifiers at Dagogo.

http://www.dagogo.com/View-Article.asp?hArticle=858

Regards,

Thanks Metralla,
Very interesting to read this review and then read Srajan Ebaen`s review of the same 300b tube comparision in the June 2010 6 Moons. Different ears ,systems and various amps lead to different conclusions.

"The tubes don't hold bias well neither. Every other few days, I would need to re-bias the tubes.”

Bsimpson,
My experience couldn’t be more different. I installed the Royal Princesses and after three hours, set the bias at 1.09. By the next day, one channel drifted to 1.08. Having read your post, and it being about a month since my last check, I took new readings and measured one channel at 1.07 and the other at 1.08. While I only kept Sophia’s Carbon Plates for about a week, they seemed similarly stable. I guess I can only hope that your experience with short tube life will prove equally atypical. At least for me.

Do not want to repeat myself again, but I think for those who own mono's or not Adaptive auto bias amps this can be a very huge issue.
Thing is, many manufactures offering auto-bias right now, so, this keeps you away of the fact what ever your tubes are stable or not, cos you just don't see that, so, why bother? The guys from PrimaLuna developed Adaptive Auto Bias http://www.primaluna-usa.com/product-main/prologue/prologue-two , which offering you the best possible solution and the reason, I believe, is basically the mass production of really bad tubes, which are used all over the world. You should see the stock KT88 I got when I bought Prologue Two, very poor quality and cheap material. They even dare to say that they produce a decent sound. Well, I don’t think so…
So, to me, tubes should be at very high quality, especially when their price range starts around USD 350-400 for a pair, not even want to start about USD 1000 a pair, which Royal's are, but that's not what we were talking about, cos not many users are around who bought a pair , I guess, and I do hope their quality check is better now. But than again, if you have to get the quality at that price range only, man, I am out, even they sound great.