Anyone Here Have Atma-Sphere Amps?


I find these amps very intriguing and was wondering what people with real experience think. I have read all the reviews
which are generally excellent except for some reason Stereophile has not reviewed them as far as I can tell.
The main question I have is how often if ever do you blow a tube and how long are your tubes lasting. Do you have any quibbles. I would love to find an MA 3 owner as that is one ballsy amplifier. There is no such thing as overkill when it comes to power amps.
mijostyn
I have been an Atma-Sphere customer for some time. I use the M60s in my system. They drive either Spendor 1/2e or Quad ESL 57 speakers. For speakers with difficult loads I use a set of Zero autoformers between the M60s and the speakers so that the amps sees a higher impedance. As Ralph has stated many times on these forums all amps behave better driving higher speaker loads.
Also, I would note that an Atma-Sphere OTL will put out less power into lower speaker impedance loads and more power into higher loads vs. a high current sold state amp that doubles power as the impedance is halved, but has reduced power as the load doubles. Ultimately I pay less attention to power these days. I'm more interested in how much distortion the amp is going to put out (it will put out less into higher loads) and if I can get my desired SPL level in my room with the amp and speaker of my choice. I find 30 - 60 watts is plenty for me.
Atmasphere, The lower the impedance the less efficient a speaker becomes. Transformerless SS amps respond to this by putting out more power and as long as their output sections can handle it and the power supplies can dish it out everyone is happy. Amps with transformers and your OTLs dish out constant power regardless of speaker impedance. So what happens when you try to drive say Wilsons which have notorious labile impedance curves? As the impedance falls and the speaker becomes more inefficient wouldn't these amps run out of grunt? I understand this is frequency dependent but I am not exactly sure how. Does the sensitivity of these speakers increase as the impedance falls?
Is a 200 watt OTL amp less powerful than a 200 watt direct coupled amp
or rather not as capable of the same high volume limits under this circumstance? Pardon me for being...an idiot but when it comes to these things I guess I am. I know what I want to hear and what has worked for me in the past. The next time I want to upgrade I would like to get it right the first time around as the stakes are much higher.

@mijostyn   Your Sound Labs don't behave with the 'lower the impedance the less efficient a speaker becomes' rule that is common with box speakers (although that description isn't entirely accurate...). IOW they maintain the same efficiency as their impedance goes up or down.


Regarding Wilsons, the national sales manager of Wilson ran Atma-Sphere amps for many years. I've heard our MA-1s with the Sashas and they seemed to work well together.

Regarding power- 200 watts is 200 watt regardless of what kind of amp makes the power.

I am using Atma Sphere M-60 MK III.2 & MP-1 with Quad ESL 2912. I am very happy with this setup. Many people use Atma Sphere with electrostatics. This is realy something special. Previously I have used Quad II eighty, EAR Yoshino V12 and some other amps with all kind of electrostatics. Atma Sphere is much much better in every possible way. I'm looking to upgrade to MA-1 so if any of Atma Sphere fans in Europe is selling one, please contact me.
Thanx twodolfins. I am certainly going to use them with ESLs. Good luck in finding your MA-1s!