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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

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almarg's avatar
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almarg
8,673 posts
 
BTW, Ozzie, I suspect that the X350.5 spec of "40 watts peak" for the point at which it leaves class A operation is equivalent to only 20 watts based on the usual conventions for defining amplifier power (corresponding to volts x amps with each defined on an "RMS" (root-mean-square) basis, rather than a peak basis).

So you’ve probably been using very little of that amp’s power capability.

Regards,
-- Al

ozzy's avatar
ozzy OP
3,650 posts
 

Al,

Thanks. I just got news that the used M-60's that I bought site unseen have arrived at Atmasphere for the 3.3, V Caps, power supply and extra binding posts (for Bi-wire) upgrades.

So maybe in a week or two I'll be able to try them out.

ozzy

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swampwalker
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I am pretty sure you will love those amps.  One of the only equipment sales I regret is a pair of  the M-60s.  Luckily, I now have more efficient speakers and I got a good deal on used S-30 w the V-cap and power boost mods.  Love it.  An added bonus is having the best customer support in the business available to you.  
ozzy's avatar
ozzy OP
3,650 posts
 

swampwalker,

Thanks for the posting. My speakers are DIY so I only know the individual driver specs. I hope they are an easy load for the amps.

ozzy

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swampwalker
5,132 posts
 
ozzy- FWIW, mine are too, although to be correct, they are DIS...do-it-someone else ;-).  The S-30 drives Feastrex quasi-full range field coils, reportedly about 94dB, crossed over at about 60 hZ to a Class D Crown for the low end.   So it is an easy load.  When I had the M-60s, I was using Merlin VSM-MMs. 
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