Atma-Sphere M60 or David Berning ZH270?

Hello Laoyuap,

Yes you can run the M-60 with only 4 tubes per channel. With most speakers that probably wouldn't work well, but your 14-ohm Coincidents are a special case.

When you reduce the number of output tubes in an Atma-Sphere amp, you not only reduce the power output but you also reduce the damping factor (or increase the output impedance - same thing). This means that the bass will not be as well controlled, with most speakers. But if you have high impedance speakers like yours, the bass will probably still be well enough controlled, and the combination should work very well. And the midrange might be just a wee bit better with fewer output tubes.

I don't know of any other amplifiers where you can safely remove output tubes and still operate the amplifier. I'm sure they exist, but just don't know of any offhand.

Best of luck to you,

Duke

Laoyuap-
Duke's comment "At that which they do well - which is lifelike timbres and textures, engaging liveliness, and rich inner harmonic detail - the Atma-Spheres are truly superb." is right on the money. I listen to mostly solo and small combo, non-amplified music (folk, blue-grass, blues, some jazz, lots of singer-songwriter stuff, some older rock), and those qualities are exactly what I value. I don't have any experience with either of those amps with full scale orchestral type stuff, bu the solo violin and chamber should be great with the Atmas. I think the Berning is more neutral, faster. The best way to explain it in terms of your musical tastes (forgive me if I'm way off base, I said I'm no classical fan) is just different readings of the same score, or different character of 2 different, great old violins. As far as the practical aspects go, the Berning is the clear winner. Besides those noted above, the Atmas are monoblocks AND (a very big and) laid out with the inputs and the outputs both in the front of the amp (may have changed on new versions). This is a a pain, since with manual biasing (no big deal by the way), you need visual and manual access to the front of the amp, which is where the input jacks and speaker posts are, but the power cord IEC is on the back. If you can place them behind each speaker, with a long IC and short speaker cables, it might work out pretty well, but then there's the kid-factor.

I too have found the Atmasphere amplifiers to be superb. Certainly one the best amplifies that I have heard. Although the Atmasphere may be more fussy about speaker impedance values, and swings, this can be mitigated with the use of the Zero auto-transformer, a device which effectively optimizes the impedance match between the amplifier and the speaker thus allowing the amplifier to synergetically mate with a speaker and realize all the desireable attributes of the OTL design.

I have run both the MA-1 and MA-2 with, and without, the auto-transformer on my Magnepan 3.6's. Also with the MA-1, I pulled tubes to emulate the M60. With the auto-transformer, the vibrant and delicate soundfield was downright arresting. It just sounded like it was suppose to sound - very immediate, very lucid and very real. Nothing hyper-uppered about the Atmasphere.

Speaking about the M60, there is a picture of the new M60 that Ralph is making on one of the sites covering the CES show. It's nice looking unit. I don't know if it is any different to the venerable M60 but, it's worth checking out.

Ralph's newest Rendition Audio Monitor 60 monoblock amplifier: http://www.renditionaudio.com/monitor60.html...


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As our very dear friend Michael (Swampwalker), has owned the Berning ZH270, AtmaSphere M60, AND a Joule Electra, he is the authority here. From his experiences and perspectives, which I trust a great deal, the Atmas are a bit warmer and richer than the Bernings. This would suggest a better marriage with the Coincidents...

But, as Spencer pointed out, with my Coincidents, which are incidentally warmer and more full bodied than any other pair you will find out there, the OTL sound does not seem to suit them as well. Not that the sound is bad, but it is does have a bit of harshness and brightness that I was never able to get rid of with my MKII.2. The MKII.3, plus a lot of upgrades instills the liquidity that I need into the sound.

Still, after the holidays with my Granite monoblocks, and ESPECIALLY this past weekend with my Jadis, I am more or less convinced that the Coincidents sound best with a transformer coupled tube amplifier. I know that the rumor is that Israel Blume has used the M60s to voice his speakers (and a call to him will show he knows A LOT about the amps), when he released his own line of tube amps, they were transformer coupled SET 300B based. And, at CES, for the past several years, he has partnered with EveAnna Manley, to rave review.

In my experience, an OTL amp seems to mesh better with a more relaxed speaker, such as Spencer's Merlins. That Dynaudio Esotar is a much smoother tweeter than the ScanSpeak Revelator used in many of the Coincidents. This is not to say which tweeter is better or worse, as both have their legions of devoted followers.

And, for whatever reason, as Spencer said, my specially modified pair of Frieds (they were Bud's own pair up until we got him a new pair of Studio VIIs this fall), seem to just make really good sound with the AtmaSphere M60s. I think it's the "resistive load" loudspeaker that meshes so well with the OTL (remember, Ralph owned Frieds for so many years).

For what it's worth, I am not a fan of running less tubes in the Atmas. Yes, you'll throw off less heat. Yes, you'll use less electricity. Yes, this. Yes, that. But, if you are really concerned about these issues, I would say that the sonics of the two amps are probably similar enough to say that the Berning would be the obvious choice.