Amps Atma-Sphere M-60 Mono blocks OTL design

bdp242,110 posts03-14-2017 10:34pmAnd potentially the 4th of July for the ARC owner. ;-)

Ok guys here it comes...

Well, at this point here’s an update of my opinion of the Atma-Sphere M-60’s compared to my Pass Labs X350.5.

First off, the cu V-Caps have maybe 40 hours on them. I recall reading somewhere that these caps take the longest of all caps to break in. Somewhere between 250-500 hours! Ralph from Atma-Sphere indicated 140 hours is probably all they need. Also, I am still using the older mismatch tubes that came with the used M-60’s. In addition, some of my favorite tweaks did not apply well with the M-60’s. One of them that surprised me was the Synergistic Research carbon XOT’s. The XOT’s placed at the speaker cable ends had provided a nice sharpening of the image. But now with the Atma-Sphere amps the sound was limited in the frequency extremes. I think they must have had a conflict with the M-60’s 4 ohm output impedance. So, I ended up selling them!

So, with all that being mentioned, I am getting some very nice sound quality even at this early point in the break in process. There is a very wide and deep soundstage. There is a smoothness that is hard to describe. It is not a veiling of upper frequencies for I have noticed so many chimes, bells and every king of tingling sounds imaginable in familiar recordings that I did not notice before. No, it is a smoothness that makes it easy to listen to music for long intervals. The vocals are pure and true and to me very lifelike. And although I am crossing over the lower bass at 100 Hz to (2) JL Audio F-113 subs the bass notes are taking on a more definitive tone. That is, you can follow the walking of the bass lines better, very enjoyable. Evidently the bass notes do not just reside in just the lower range.

I originally thought that playing music as loud as before (compared to my high power SS amp) might be a problem. Yeah, I’m an old time rocker (64 years old). And, I have been known to crank it up to, “feel the music”. All you air guitar rockers know what I mean… With the M-60’s, I can still play the music quite loud with my DIY speakers and external crossover’s. So, I did a good job matching the driver components to mesh well with the Atma-Sphere’s. But, the weird thing is, I find myself listening at lower sound levels more than before and I don’t know why.

Both of the amps (Pass Labs & Atma-Sphere) have their sonic qualities. I do however believe that my Pass Labs amp has more dynamic’s and will play significantly louder, especially with lower impedance speakers like my old Eggleston Andra 2’s. The Pass Labs also has more slam and startle factor, and they do have similar warmth as the Atma-Spheres

The Atma-Sphere M-60’s have a purer tone and I think reveal a little more detail. I have many audio recordings that I recorded through the decades of live performances from TV/Cable/Satellite broadcasts (the Tonight Show, Jay Leno, Grammy award shows and such) that with the M-60’s I now detect distortion. Distortion that I never knew were in those TV/Cable/Satellite recordings with the Pass Labs amp.

At this moment, my preference is the Atma-Sphere M-60’s over the Pass Labs for its higher sonic purity. And I love those dimly lit tubes! But, we audiophiles are a fickle bunch that changes minds often. If I change speakers or if I long for more slam and loudness the Pass Labs will be sitting on the sidelines. I don’t intend to sell either product at this time.

ozzy