711Smilin, your heart is in the right place. You should buy the pair on auction here for the tsunami victims. I offer my personal debt of gratitude to you and Ralph for making this happen.
I actually spoke to Ralph about them this week. They will be built soon, and have the MKII.3 circuit, with the switch to choose Class A or AB. It is his way of giving back, he and I are big believers in kharma. Ralph feels forever endebted to us for taking a stand for him. I feel that we could never pay him back, even if we did what we did a million times, for all of the good the man has done in his life.
I have ZERO idea why anyone would want to run their Atmas in Class AB. Well, yes, I do. They will throw off a lot less heat, as well as using less electricity. But, as the sound will surely take a step down, in my opinion, those interested in Class AB should look elsewhere. Ralph doesn't agree with running them in Class AB, it was a design of the non Ralph regime, and he has told me new designs will forego it in the interest of offering the best sound, at a lower cost (less circuit complexity).
The 12SX7 mod causes no damage to the amp whatsoever. Ralph and I have spoken at length about it, and while he concedes that the tube offers superior sound to any 6SN7, it does not meet his 20 Year Rule, as the tube is no longer in production. One of the reasons Ralph is such a prince is that he wants his customers to be sure that their purchase will still be viable in 20 years.
I think that if prodded, he would do the mod, as it is simple (you just run off of one of the other transformer taps) and easily reversible for anyone who would ever go back (you just switch the wire back to the other tap).
Personally, I disagree with the rationale for not running the 12SX7 - cost. I just bought 8 NOS 12SX7 tubes for $100 last Saturday. I now have more than 2 full sets in reserve. I don't know how long 6SN7 tubes last, but it should be a minimum of 10 years in most tube amps, and probably a lot longer. With the set in my amp, plus two in reserve, I'm probably OK even if I use the amps when I'm 80 years old (I'm 35 now). And, remember, if need be, I could always go back to the 6SN7 after moving just one wire.
Going along with the feelings of everyone I have talked to, including Ralph, that the tube DOES eclipse any 6SN7, tell me where you are going to get a tube that sounds this good for $8 - $30 per tube? Heck, the cheap Sovtek 6SN7s are $10 - $20 each. I know when I was buying good 6SN7 tubes for my last pair of Atmas, I could never find anything for these prices. Yes, they have spiked in price, and it is solely due to Atma Sphere owners such as myself buying them up, but the price is still a fraction of a Sylvania, RCA, or KenRad 6SN7.
Finally, because a tube is no longer in production does not mean it will not go back into production. ElectroHarmonix recently began producing KT90 tubes, which were only produced by Ei in the past and were thought to be soon extinct (NATO destroyed the factory in the 1998 bombing of Yugoslavia). Why did EH start making the tube? Demand, of course. There is money to be made there. If tube amp manufacturers try the 12SX7 and feel it to be superior to the 6SN7 (I hear more and more people talking about the 12SX7) we will start seeing them use it (Denis Had of Cary uses a lot of out of production tubes in his Cary and AES products), and some company like EH, JJ, or Shuguang will begin producing it once again (look at all the tubes that have gone back into production because of Dennis Had). It Economics 101. And, we will be taking audio to a higher plane. Some people focus on problems, I try to live my life by focusing on solutions. It's a glass half empty - glass half full thing.
