Atma-sphere M60 II.3-Any good for 4 ohm speaker?

Ralph is back!

Many of you may not be aware of the fact that Ralph Karsten has returned to Atma-sphere, along with his proven track record of product development, customer service, quality, and integrity. The other parties who were briefly running Atma-sphere during Ralph's "departure" in 2004 are no longer affiliated, in any manner, with Atma-sphere. I don't wish to comment further concerning details, since I don't want to see this thread closed. In short, Atma-sphere is back to the same high quality operation for which it has been known for the past 25(?) years!

711smilin, call Atma-sphere (Ralph or Bill) since they will be able to best help you with your decision. And forget about the tax write-off, which only comes into play for an amount OVER the fair market value of a charity item!

Trelja, I would check with Atma-sphere regarding the 12SX7 tube mods. I was lead to believe that this mod was not good for transformer longevity, but I may be mistaken. I was discussing several issues about my amps, and could have misinterpreted or confused information about the 12SX7 mod.

Fatparrot,

Thanks for clarifying that "Ralph is back!" It is good to have him available at A-S once again to talk with.

As to the 12SX7 mod, I haven't heard about this creating any problems. The main considerations for Ralph when I asked about this mod are: (1) increasing cost of the 12SX7 on the vintage tube market; (2) significantly decreasing availability and no "new" production; (3) much better availability of the 6SN7, including great sounding vintage stock (although the vintage is also getting more costly). In short, he's not a fan of this mod and doesn't recommend it for these reasons even though many people report liking the sonic change.
.

Rushton may I be honored to say friend, There is a peculiar phenomena when it comes to the supply of old tubes. They come out of every nook and cranny when the demand goes up.
That doesn't address the issue of a low impedance speaker with an OTL sans autoformer. I have heard high powered ones with Avalons on a couple of occasions with excellent results. I have heard Ralph's reputed personal favorite the 60s with the undeniably true Frieds do a great job with the resistive load of the Real thing but have also heard tell of the 30s failing to power a demanding load due a less "benign" impedance load.
Thus get the power and/or make sure your impedance is very firm or will tend to rise before it drops.

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.

Oh, one issue I forgot to address are the chassis of the M60 MKII.3.

There are currently THREE different chassis available.

The old style, with the tubes in the front, transformers in the back, and the squared off transformer covers. This is the classic M60 design.

The "other regime" style, with the transformers running longitudinally down the middle of the amps, with tubes on either side. It looks like the S30 and MA1. I believe Ralph is not a fan of this design and it will be going by the wayside.

The third style is the Rendition, which returns to the classic M60 layout, updated with rounded transformer covers and a stainless steel plate in front of them. It's a takeoff on the original design.

To my eyes, the Rendition looks like the 1940's (streamlined - aerodynamic), whereas the other design looks like 1950s (modernist - contemporary). I like them both. Which do I prefer? I don't know, I keep going back and forth...

While 4 ohm speakers are not kind to the M60s, a lot of people use Reimers with low powered and SET tube amplifiers. I would at least try it. And, regarding the Zeroes, Ralph knows I find they detract from the sound (you lose the AtmaSphere magic). Atma means "soul", and I guess I would just call them Spheres at that point. Still, a lot of people are fans, so you might want to give them a try and see where you stand.