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

ozzy

Showing 37 responses by gdnrbob

Funny you should post this thread.
After 3 months of waiting. I finally got my Atma-sphere MA-1 2.2 (upgraded to 3.3) and MP-3 put into place and running.
My significant other kept hounding me-'This better be worth it'.

Well, after 30 seconds, even he noticed the improvement.
Everything was clear and defined. Drums, horns, piano, you name it, just sounded right- Alive!
I always thought my system sounded good. Now it sounds great.
I have to email Ralph and tell him, but your post got my attention and I had to reply.
Those Egglestons are really nice. A quick google shows they dip down to 4 ohm. The M 60 should be up to the task, but I would ask Ralph if you should get some Zero's.
Bob
Ozzy, I did not opt for the upgraded caps or power boost. My amps are vanilla MA-1's upgraded to 3.3
As things 'burn in', it just keeps getting better.
Bob
@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
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

Finally got the Treo's installed and with the Atma-Sphere amp and pre, they sound wonderful.
Bigboltz, do the M-60's have enough power for the Quatro's? I ended up going with the MA-1's because I thought it would be a bit too much for them.
BTW- My MP-3 took a while to complete, mostly due to the remote option, but as I said to ozzy, your patience will be rewarded.
B

@bigboltz
The remote is nice, but I find the range is limited (10 feet or so). I have to contact Ralph and see if the remote needs batteries or if I need to situate the preamp differently.
I am glad to hear the M-60's have enough punch for quatro's. I was going to get them, but my, then 3a sigs were more power hungry, and he had a pair of upgraded MA-1 v2's for sale at a good price, so I went with those. I probably should have had the hi pass incorporated, in hindsight. Those stupid M5-HP's are not very attractive hanging off the inputs. @alexysflores 
Vandersteens are pretty stable with Atma-Sphere amps, more so when using the crossovers. I think Ralph says his amps should be good with even 4 ohm loads. 
@ozzy 
If Bigboltz is doing good with M60's, I am pretty sure you will be okay.
Of course the best info would be from Ralph himself. But, if Almarg says you have been using very little power with your current amp, then I wouldn't be concerned.-Ralph's designs are not only refined, but they are tough (as in, well built).
B

Not to sound rude, but why didn't you get some tubes from Ralph?
I only got into this recently, so I don't know much regarding tubes.
Are the Russian and Chinese tubes better? I have read about tube rolling and would like to learn more.
B
Thanks ozzy, I didn’t realize that new tubes had to be conditioned. When I got my MA-1, I just installed the tubes and listened (well, I did let thing run in for a while). I didn’t know that they were pre-conditioned- Well, I hope the were.
I will be surprised if you don’t keep the Atma’s. And, should that happen, I hope you will give your reasons.
Bob
@bigboltz, sorry I have no phono stageon my preamp. I found streaming music and am hooked.
Ozzy, I hope you have gotten things settled a bit? I, and others look forward to your evaluation.
B
Thanks for posting your impressions. Your experience mirrors mine and is significantly better worded. I have no doubt that as things 'burn in', you will notice even more details.
As I have said before, I was completely amazed with how musical Ralph's amps are.
I think having two different amps is a nice way to keep things fresh.
Bob
Do you notice a difference? Can you toggle it on and off?
I am just curious, I never heard of it prior to this thread.
B
Thanks Al/Ozzy.
Since were still encased in snow here in the NE, GardenerBob hasn't been doing much gardening. So, after a sunny Friday afternoon, I have been aquainting myself with the DEQX. I still have to go through the Agon thread, but it really is interesting. (Perhaps next winters' project).
@ozzy , I probably will buy used, too. Has DEQX been okay with non original owners, in terms of support?

Bob
So, Ozzy, you managed to do the calibrations without help from DEQX?
I am reading the manual. It is pretty detailed, but seems doable.(I still haven't finished reading it completely).
 My biggest concern is interpreting the graphs. Not so much the deviations of frequency but time and phase lag. Maybe it becomes clearer when using it.
Bob

Thanks ozzy and Al! 
I have been reading and rereading the manual, as well as the thread Al linked to.It is a lot of information, and I am not the most technidally proficient person. So, sorry if I repeat something that has already been answered.

Has anyone used the DEQX on phase aligned speakers like Vandersteens? As a Treo owner, I would be curious to see what a phase aligned speaker would show on a graph. I think I saw a mention on the long  thread Almarg linked to, but I can't find it again.
Bob
@almarg , et al.
Considering how much you are doing to the original signal (when processing through the DEQX), do you think you are altering it to something 'unnatural'?
Bob
Wow, not bad. I own a pair of Zu Omen Bookshelves. They have a similar range, and I like their simplicity (crossover-less). I find it amazing that such a small enclosure can still reproduce such low frequencies.

Will you be adding subwoofers? Looking at the DEQX and its' capabilities, I would imagine that your DIY speakers and a pair of subs could possibly out perform your Egglestons.
Perhaps you could build those, too?
Bob
Not to be a pain, but I wonder if you should leave the transformers set at a connection for a period of time.
I only say this because, when I adjusted my Vandy M5-HP crossovers, Johnny Rutan said they need to settle in for a few days before they exhibit their true character. This situation may be different, but I thought I would post my thoughts with the hope of having you make the best informed decision.
(BTW- I recall reading that Steve McCormack felt that the Zero Transformers made a significant difference even with his SS amps).
Bob
Ozzy, I don't have the Zero's. I only mentioned it because when I changed the crossover settings of the M5-HP, things sounded grainy/shrill. John Rutan said it was that the circuit needed to settle in for about 60 hours or so. Hence, I was wondering that if you changed the Zero settings, it, too, might need to 'burn in' in order for you to gauge the differences in sound quality. As I said, it may not be the same thing, but I thought I would mention it.
Glad to hear the Atma's living up to your wishes.
Bob
I am glad to hear you find the Zero’s benefit your system.
I have to say that I am surprised that they would make such a difference, considering that you have very efficient speakers to begin with.
Bob
Hmmm, now I wonder if I should give them a try?
Ozzy, did you get them boxed or naked? 
Bob
It seems my post was a bit too much ( I can't type outre with the Accent Grave on my keyboard).
Gee, I thought if the President said it, it was okay.
B
What were they replacing? This thread is getting pretty long. If I recall, they were pretty old.
And, where did you buy them? I am using the stock tubes from Atma-of which, I have no complaints, but am always interested in 'upgrades'.
Bob
As this is my first Tube Amp and Preamp, I have no idea who sells these, nor who is a good source. So, where do you guys get these tubes?
Bob
Thanks!
So, how do you know if the tubes are okay? I haven't seen a tube tester since I went to the supermarket with my parents 60 years ago.

Bob
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
Holy Cow!- Considering that your speakers are far more efficient than my Vandy Treo's, you have me thinking about adding a pair. I recall Steve McCormack saying that the Zero's do make a difference, even with Solid State.
Bob
Yes, I have the Vandy 2w's, but just bought a pair of 2wq's.
I probably didn't have to, but it was in the back of my mind, so heck, I did it.
I was looking at a pair of Quatro's here on Agon, but decided to keep the Treo's as I:
1. Love the way they look and sound.
2. Can't get the energy to move another pair of speakers.
B