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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
7,523 posts
 

charles1dad,

Thank you.

In the end I am not rich and after a fair comparison period, I will sell off one of the amps.

ozzy

charles1dad's avatar
charles1dad
10,250 posts
 
Ozzy,
Believe me I understand.  These two amplifiers are of such different design and topology and I'm always very interested as to what someone hears in comparison. 
Charles 
atmasphere's avatar
atmasphere
11,918 posts
 
I do not think the ZEROs will be useful on this speaker.

The ZEROs should always be regarded as a problem solver (and for any amplifier). The problem is that the amp sounds worse without them, in a nutshell. If the amp sounds better without them then it should be a no-brainer that you don't need them.

M-60s do quite well on an 8 ohm load- the only issue I question is whether 60 watts is enough power, but since this system also employs a subwoofer and crossover, I don't expect that to be an issue.
ozzy's avatar
ozzy OP
7,523 posts
 

atmasphere,

Thanks for the comments. My Pass Labs amp is rated at 350 watts A/B rms per channel but I think it only puts out 30 watts in class A. Supposedly, once the meter starts to move it is leaving class A for class B.

With my present DIY speakers, the needle does not budge, so I'm thinking I may be only using less than 30 watts.

ozzy

gdnrbob
4,457 posts
 
@ozzy 
The Atma-Sphere amps do get hot. In fact, they raise the temperature about a few degrees 2 feet away (I have to relocate my thermostat to the opposite side of the wall now). Though I have opted to mount them on the wall rather than a rack, so they get lots of air circulation.
Do they warm up the room, not really, but it doesn't get cold as fast as it used to.
Bob
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