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Amps Atma-Sphere M-60 Mono blocks OTL design

I just purchased a used OTL Atma-Sphere M-60 mono blocks that I have sent to Atma-Sphere to be upgraded to the current model 3.3 and I also added the option of a higher quality power supply and V caps.

I have sold my old trusted Eggleston Andra 2’s speakers and have built some monitors using Aurum Cantus ribbons (102db) and Aurum Cantus midwoofers (90db) that are both rated as 8 ohm nominal. I have a DEQX Premate and will be crossing over to (2) JL Audio F-113 subs at 80hz.

Currently I am using a solid state high power stereo amp (Pass Labs) that I used with the Andra 2’s.

The Atma-Sphere M-60 is rated at 60 watts class A and is said to work better with higher impedance loads.

It will probably be a few weeks until I get the M-60 and was hoping someone could provide opinions of what to expect.

I listen to late 60 early 70’s classic rock music mostly. Sometimes loud.

ozzy

128x128ozzy
mdvuolo
40 posts
 
To All,
I'm going to ask a question that I think is relevant.  A little less than a year ago I purchased the latest (3.3) version of the M-60's, without upgrades, directly from Ralph and have been a very pleased listener, using a little tube rolling. This my first venture into tube amplifiers, after starting with a couple different tube preamps, and, again, I'm very pleased with these lively amps.  My question is related to the three available upgrades: V-caps, power supply, or Caddock resistors.  Can anyone weigh in on the individual/relative benefits of the upgrades for these amps?

Thanks,
Mark 
charles1dad's avatar
charles1dad
10,250 posts
 
If the question is which of the three options is the most impactful, I’d say addressing the power supply. Power supply quality is foundational and as a result mandatory for high quality sound performance. The other two upgrades are important contributors to good sound, everything seems to matter (of varying degrees) when  it comes to audio products. But again power supply would be my initial step.

Obviously Ralph can provide expert guidance as he both designed and built your amplifier.
Charles
ozzy's avatar
ozzy OP
7,502 posts
 

mdvuolo,

I too have searched for info on the upgrades. What Ralph told me was that the best bang for the buck is the cap and power upgrades. The Caddock resistor upgrade is an improvement but rather costly compared to the other upgrades.

ozzy

mdvuolo
40 posts
 
Thanks to charles1dad and ozzy,

I, too, spoke to Ralph.  I hope I won't misquote, but he told me that the cap upgrade would improve transparency and that the power upgrade would improve smoothness at higher volume levels.  He said that the Caddock resistors would reduce "electronic haze".  I don't know if there is anyone else out there who could post about actual related experience.

Ozzy, I'm looking forward to you posting about your own listening experience.

Mark
gdnrbob
4,452 posts
 
As an owner of 'vanilla' MA-1's, I can say they exceed all my expectations. I can hardly believe that he can 'improve transparancy' or 'smoothness'. But, now you got me thinking maybe I should....
Bob

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