2. amps-preamps
  3. 128359-41

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
7,421 posts
 

knghifi,

I did a search on EBay. There are quite a lot to pick from.

gdnrbob,

Thanks, I went this far expecting big things from the M-60's. But, I'm still not quite sure what to expect. After all, I will be coming from a SS amp that had all the power I ever needed and which has had many reviews that claim the Pass Labs amps has a tube like sound.

So, soon I will know about the Atma-Sphere.

Thanks Ralph for the additional information.

ozzy

charles1dad's avatar
charles1dad
10,249 posts
 
Pass Labs vs Atma-Sphere,  two thoroughbreds,  should be quite interesting. 
Charles 
bigboltz
55 posts
 
gdnrbob,

I'll get my MP-3 this week. I was wondering if yours has the phono stage and if so, what do you think? What others have you had for comparison?
atmasphere's avatar
atmasphere
11,753 posts
 
Where's a good source for Russian and Chinese 6AS7?  
We stock both and both are available on ebay.

Usually when we ship a set of amps we precondition the tubes first and then play them. In this case since the amp was used it came with its own tubes. So we tested them and played them. Its not quite the same...

At any rate, over the years we've been researching how the tubes fail. Most of them fail immediately after shipment or else when they reach the end of their service life (which can often be 10,000 hours or more). The 'after shipment' part is what concerns us most.

What we've been finding is that most of the tubes fail due to arc-over and subsequent damage to the internal elements. It appears that the mechanism is the cathode coating, which is very much like a paint applied to the cathode (but in this case improves the cathode's ability to emit electrons; this is true of all tubes). The cathode coating can flake apart just like old house paint and if the tube is conducting the tube can arc as the flakes are conductive. Since many of these tiny flakes can be loosened during shipment, if the tube is subsequently subjected to a prolonged heating cycle most of the flakes that are occurring can fall harmlessly to the bottom of the tube and then the tube can provide normal service after that.

This applies to any in-directly heated power tube and is nothing unique to the tube we use. IOW running the amp in Standby for a few hours is a good practice anytime its been shipped, assuming the amp has a Standby function.
gdnrbob
4,441 posts
 
@bigboltz, sorry I have no phono stageon my preamp. I found streaming music and am hooked.
More to discover