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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
ozzy's avatar
ozzy OP
7,542 posts
 

gdnrbob,

Well since they are currently in production you can buy them new from the Vendors charles1dad mentioned. Buying through EBay is a little more risky but like on Audiogon you check the sellers reviews and take a chance. I have not had a single Sophia or Full Music tube fail thus far. But, I have had a NOS vintage RCA fail.

almarg,

You always post such great information and I thank you. Perhaps with other tube amps the Sophia/Full Music tubes would be a problem but with the M-60's they are good.

ozzy

gdnrbob
4,460 posts
 
Thanks Ozzy and Almarg.
You guys are the best.
Bob
atmasphere's avatar
atmasphere
11,963 posts
 
So far we've yet to hear about any hum problems with the Sophia or TJ Music tube. Al's report is the first I've seen.

We made a circuit change in our amps regarding how our filament circuit is handled about 12 years ago. That really reduced the hum issues caused by cathode/filament leakage; every now and then we run into a bad tube in the field causing a problem but its nothing like it was before we made that change. So I suspect much relies on the circuit design.

FWIW in our preamps the leakage would be a non-issue.
gdnrbob
4,460 posts
 
Ralph, I am still awed by what your amp and preamp can do.
After growing up on tubes, I never thought I would return to them, but, you did it.
Bob
lowrider57's avatar
lowrider57
5,418 posts
 
Was wondering if anybody has tried audiophile fuses in Atma-sphere gear? Does the design make a fuse change irrelevant?
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