Atmasphere amps trustable?


Tube world, a big world, then I came acorss the Atmasphere on the net, looks different from those common tube stuff... kinda weird, the M-60 uses 8x 6AS7G output tube and 4x 6SN7 driver tube per channel, where're the rectifier tubes? Plus they're so-called OTL, sounds even more weird.
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Atmasphere amps are fabulous. There are many great aspects of the OTL sound that can be found in the many reviews of their gear. As with much amplification and maybe to a greater extent due to the unique amp characteristics, matching amp to speakers is key. 
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Atamasphere amps might sound great but the "trust" factor could be an issue. I've heard that these amps can go through your personal items when you're not around, and there was one incident (not verified) I heard about where on of these OTL amps ran off with the owner's sister, and another where the amp ate the family cat. Sure they are wonderful sounding amps but can you trust them? Risky…just seems risky...
Any amp that eats cats can't be all bad.  Seriously, Atmasphere amps are very well regarded.  Not hard to find lots of OTL fans around here.   
@Wolf-  You misread the name on those amps.  Those were not Atmasphere amps(made in the USA), but Atmohammud amps(imported from Syria).    Can't take your eyes off of them, for a second!
Because OTL amps are impressive looking with the tube array, there are reports  of the significant other in a relationship  being lured, subsequently boarding a plane to Fiji with that particular model.

Rectification is likely S.S.-diode.

Seriously?
I believe that any amp if pissed off by cat can get angry and eat that little bastard!


"Mommywahwah": That type of response to the OP is utterly uncalled for. The OP simply wanted to have a discussion about this brand of OTL and become informed via help and support from our community. If you’re not able to participate in a civil manner and help be supportive, you are antithetical to the existence, and interest, in this hobby/pastime/enjoyment/entertainment endeavor. If you think that’s your charter and mission, then stay away.

Keep your poison and your anger to yourself and get off your high horse. If you have something positive to say, then say it, otherwise keep it to yourself. That’s not why we’re here and not what is helpful and supportive in growing interest in the enjoyment of audio gear and music listening.
If by "weird" what the OP means is different, then I would say that’s a fair assessment in that my understanding is the high output impedance of an OTL amp (with no negative feedback employed either by design in the case of Atmasphere amps as I understand it) means one is best advised to match speakers with it that also have higher impedance ratings than many, 8OHMs nominal impedance or higher.

Ralph Karsten who is Atmasphere is very knowledgeable and posts here regularly as many here know. He talks about a different "paradigm" than the norm that his products fit into which is an accurate assessment IMHO.

Also worth noting I’ve heard the Atmasphere amps set up well with appropriate nicely matched gear at shows and the sound quality is always top tier. Also that the company and products have been around for awhile and seem to have a quite sterling reputation which bodes well in regards to the "trust’ factor.




mtoc, Ralph Karsten posts here and there are many discussions about his amps which he participates in. Just type Atmasphere into the search function.

Ralph’s amps are highly regarded by many. Power tubes can blow though, and I don’t know how well protected Ralph’s amps are if this happens or what kind of warranty Ralph offers. I’m sure Ralph would be happy to discuss it with you if you gave him a call.

stevecham,
the OP’s post is derogatory, clearly he’s not done any research on this matter, doesn’t know that Atma-sphere is most helpful in these forums & that his amps are in production for the last 40 yrs, are very reliable & yet we should pander to such a troll post? You take the cake Stevecham. Keep doing this & Audiogon will not be a place to hang out anymore. Your sort of response will only encourage others to create similar posts....
Yes, I could have written it better but my frustration lay in the fact that the obvious research was not done by the OP. He just damned the Atma-sphere brand without seemingly knowing anything about it.
I believe that what he needs to be told is to search the archives & learn about OTLs & then have a more intelligent discussion with the forum.
Plus, this topic (of Atma-sphere amp reliability) has been discussed here many times. here’s just one such thread:
https://forum.audiogon.com/discussions/thought-on-otl-tube-amps/post?highlight=atma%2Bsphere%2Bamp%2Breliability&postid=825877#825877

the least he could have done was to read-up before casting doubt on a brand. I believe it’s a troll post...

"Retro" would be a much more apt term for the look of Ralph’s amplifiers than "weird." And they are intentionally designed with a retro appearance, partly as a matter of aesthetics, and partly (as I recall Ralph stating here in a past thread) because it keeps the costs of the amps lower than they would be with other approaches to their physical design.

As others have alluded to his designs are highly regarded world-class performers, when paired with appropriate speakers. They can also be used with speakers having impedance characteristics that are low or otherwise difficult by using a "Zero autoformer" at their outputs. (Which contrary to misconceptions that are sometimes expressed is not likely to negate much if any of the benefit provided by their output transformerless design, IMO).

As others have alluded to above Ralph is a regular contributor here, and is a completely class act.

Wolfie, as is often the case your post provided the best laugh of the day :-)

Regards,
-- Al

There are many "retro" looking tube amplifiers out there these days. I believe Atmasphere has been around longer than most and is a trend setter in that regard. Few still are OTLs though it seems. OTL tube amps are definitely a rarer breed but have a lot of unique potential benefits to tout, much like SET and even radically different and newer Class D amps.
Yes why would you think they weren't?

So,  mtoc,  it sounds like Atmosphere makes a solid product. Some of his products have more tubes than I can count,  but I wouldn't blink at owning one and as your have heard,  the Owner Ralph Karsten is a stand up guy and will certainly stand behind his product.  It seems like this could have been a rough thread on you personally,  but the short answer is.... Don't be leery of an Atmosphere product,  They're Quality Goods. 

Wolfe,  were you ever a comedian?  Did you do a stand up in the middle of your shows?  I bet you said some things live that you wish you hadn't and I bet that was funny.

I hope all of this helps,  Tim

Wolfe, your great but some here don't understand your humor. 
I've got Ralph's Novacron renditions and they are totally relieable .  
Mtoc,

The Atmasphere amps (like all OTLs) aren't necessarily a great match for every speaker, and they're known for producing a lot of heat, but they are highly regarded when properly mated.  The company has been around forever.  

I owned an early production Atma S-30 integrated amp many years back.  Excellent product backed by a very responsive company.  If you've got appropriate speakers, I wouldn't hesitate to buy from  Atmasphere.
They are totally weird!
I even heard that 'Weird Al' Yankovic owns Atmasphere amps!!!
Stevecham: I'm always amused by those that chastise someone else for contributing nothing to the subject at hand, yet contribute nothing themselves beyond the criticism of the offending poster.

I didn't contribute anything (sorry), but I'm sure your rebuttal won't either.
Unfortunately, my experience with my M-60 was not all that great.  I bought it new about 4 years ago through an authorized dealer.  Within the first 3 months, 3 output tube failures. Every time a tube failed, I would hear a loud pop through my speakers scaring the c***p out of me.  Tube hiss was another issue.  Power transformer hum was another.  By far the noisiest tube amp I've owned. After 6 months, I sold it and never looked back.

On the positive side, it had the best high frequency I've ever heard from any amp.  Smooth, crystal clear, and detailed.


B: I hear you, thank you.

When I encountered the OTL concept for the first time and read about Futterman's early efforts along with a few editorial accounts of experiencing "sonic bliss" but with the acknowledgment of some (potentially tube only-based) unreliability issues, I researched more and learned about a design that seems to make sonic sense on paper, and in some critical listening, but has challenges matching optimally to the impedance spectra of many well known and popular speakers. Still, the ability to make it work reliably and sonically is cited to have improved even though the ~4 Ohm output impedance still seems to a limiting factor; it's difficult to apply the ten-to-one minimal nominal speaker to amplifier impedance ratio often cited in order to maintain flat frequency response.  

I would love to hear an OTL based system properly set up. So, perhaps while I don't know what I'm talking about either, I am interested in hearing from those with real experience owning and living with OTL amplifiers. I also agree that to jump to a critical stance without knowing is not the best choice, but I am humbled by the experience and expertise of others to help enlighten. 
Been reading about Transcendent’s products. I want to build one (or two monos)!
Tubes are retro of course from the beginning.
They're noisy, require LOTS of wall power; generate LOTS of heat(especially OTL ones!) and LOTS of distortion(even considering even order ones) making the playback far from real. Very often the soundstage will seem like sounds from far away. Also as tubes about to become bad, these unpleasant effects multimultiply including some unwanted echo, RF or EM interference or microphony. Tube components indeed sound different, but they're just toys and nothing serious no matter of reputation or credibility of one or another manufacturer. 
Stevecham 8-4-2016 10:34 pm edt
... the ~4 Ohm output impedance still seems to a limiting factor; it's difficult to apply the ten-to-one minimal nominal speaker to amplifier impedance ratio often cited in order to maintain flat frequency response.
Many and I believe the majority of tube amps of all kinds will not meet that criterion.  For an 8 ohm speaker it would imply a damping factor of 10 or more.  Most high quality tube amps seem to have damping factors somewhere between 8 and 2 (with some being even lower than that), corresponding to effective output impedances of between 1 and 4 ohms or so, respectively.  (Audio Research and McIntosh tube amps are among the minority having DFs greater than 10, just a bit more in the case of most ARC designs and as high as the low to mid 20s in some McIntosh designs).

As you recognize, the 10:1 ratio you referred to will assure minimal variation of the amp's output voltage as a function of variations in speaker impedance over the frequency range.  However meeting that criterion is neither necessary nor desirable in many cases.  Assuming that the particular speaker does not require a higher damping factor for woofer control, meeting that criterion will be unnecessary and/or undesirable in the following cases:

1)The impedance of the speaker varies relatively little over the frequency range.  In that situation the amp's output voltage will vary relatively little as a function of frequency even if the ratio is much lower.   

2)The impedance of the speaker is relatively high at all frequencies.

3)The design of the speaker is such that the variations of the POWER it receives as a function of speaker impedance variations over the frequency range should be minimized for best sonics, rather than variations of the VOLTAGE it receives.  See Ralph's paper on "Paradigms in Amplifier Design."  While such speakers are in the minority, there are many such choices that are highly regarded.

4)Cases where the load impedance seen by the amp can be raised to a suitable level via a Zero autoformer.

Regards,
-- Al
 

Tubes are retro of course from the beginning.
They're noisy, require LOTS of wall power; generate LOTS of heat(especially OTL ones!) and LOTS of distortion(even considering even order ones) making the playback far from real. 

Tube components indeed sound different, but they're just toys and nothing serious no matter of reputation or credibility of one or another manufacturer.

Wow! You forgot to mention how tubes sound more natural than transistors though.

Just another DJ who judges sound by the spec sheet because they can no longer hear.
Zucka-Zucka , keep your pimp hand strong player!  ;^)
Nah, I'm just another casual dude who wants to listen to music and not play with toys.
Both times I have heard Atmasphere amps at shows, they were used with very large, very expensive high efficiency speakers from Classic Audio Reproductions.

First time in a small hotel room where the whole system was just a lot of overkill, more recently in a larger hotel ballroom where the gear had a chance to truly show what it can do and did it well.

I would like to hear the Atmasphere amps used with smaller high quality speakers that would tend to fit and work better in most peoples homes.

I have no doubt the results would also be quite top notch but the thing I wonder is if the results would be as "special" compared to others. I think of the Atmasphere products as very unique and special, not "weird", though they may look it to some.

IMHO, you have to really be a tube lover for whatever reason to live with any larger tube power amp with many tubes. TCO will be high due to power consumption and maintenance of tubes to keep things in peak operating order compared to other options ie SS.

High quality modern Class D amps of recent years are game changers IMHO. Not that they sound like many tube amps, but they do share some sonic qualities, are much smaller, have low maintenance and likely lower overall TCO (total cost of ownership) due to high efficiency, low power consumption, and no tube maintenance.

I use a tube pre-amp with 6 tubes with a Class D amp. I find this to deliver the kind of sound many tube amp lovers might enjoy with minimal use of tubes. Tube pre-amps are much more easily managed than high power tube power amps. I’d like to have no tubes eventually and am working towards that. My second system uses a true digital Class D integrated amp. The sound is quite excellent I think but will not be every tube amp lovers cup of tea for sure. I find this amp makes good quality dynamic box speakers sound like electrostats along the line of ML or Quad, but with better dynamics. I am using it currently with a pair of Dynaudio Contour monitors. Its a very interesting phenomena to hear how radically different the Dynaudios can sound in two different systems.

Also on my bucket list is to put together a third system built around a small tube integrated amp and high efficiency speakers. I enjoy putting together good sound in different ways, and on a small scale, tube gear is much easier to live with.


Absolutely untrustworthy!  I came home and found my girlfriend alone with them having a glass of wine with the lights down low!!!

But I will say, match them with the proper speakers and they make wonderful music. ;^)

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Back in my earlier and more adventurous days I bought a pair of Fourier Systems Panthere monoblocks, those with 8 of the Russian military triode 6C33CB tubes in each chassis.  They were based on the original Futterman design and were different than anything I tried previously or since.  They powered my Wilson Audio Sophias with an enormous soundstage and unmatched transparency, but did not have that lean, hyperdetailed, small-image sound that most other amps have.  I would characterize the images as "diffuse".  Using a pair of autoformers helped also.  However, in addition to doubling as space heaters, drawing 5 amps at idle, they were absolutely unreliable.  Sometimes one channel would go down, popping out a little male-shaped red circuit breaker in the back, while on other occasions they sounded less authorative and a check of tube fuses would show several were blown.  After investing in Buss fuse company stock I contacted Ralph Karstens and he offered to refurbish the amps but graciously suggested I clean and re-tension all of the tube sockets as they are tempered by the prodigious heat thrown off by the amp.  So I had a backyard project with the amps disassembled and parts all over my patio furniture, not to mention an exasperated spouse.  I then took it to Brooks Berdan and their technician replaced some diodes and other things I don't understand, and the amps then did become reliable.  However, the damage was done and I no longer trusted them and sold them to get something much more reliable.  I have never heard nor seen in person any Atma-Sphere equipment, but I did look into these and understand they use a different circuit called a Circlotron which is apparently more reliable, but almost certainly sounds different.  I have thought about matching these with my single-driver speakers but reluctant to do so based on previous experience.
Thanks for providing that input, Roger (Rlawry).

It wouldn’t surprise me if a contributor to the problems you had with the Panthere amps was indeed an inability to deal with the heat produced by the 6C33C tubes, which as you alluded to run extremely hot. They consume something like 40 watts per tube just to heat the filaments, and considerably more when bias currents and plate dissipations are taken into account. The 6AS7G power tubes Ralph’s designs use consume about 16 watts per tube to heat the filaments.

Also, for the record, a minor correction: The Panthere was produced by Fourier Components. Fourier Systems was a speaker company that existed during the 1980s, with Peter Aczel of "The Audio Critic" publication as its president. I’m pretty certain that there was no relation between the two companies.

Best regards,
-- Al

So OTL amps are like Ferrari: fast, powerful, maneuverable, but require very high maintenance to preserve an original condition due to excessive heat figures. 
I still prefer comfortable and low-maintenance Subaru over fast and powerful Ferrari.

 I have thought about matching these with my single-driver speakers but reluctant to do so based on previous experience.

If you are going to run a lower-powered speaker like a Lowther, its in your best interest to install a speaker protection fuse in the circuit if you plan to use any amplifier that can make way more power than the speaker can handle! That would include most of our amps.

In a nutshell, we would not be in business for 40 years (so far) if our amplifiers damaged speakers! But common sense should always be applied when matching audio gear.

Power tubes can blow though, and I don’t know how well protected Ralph’s amps are if this happens or what kind of warranty Ralph offers.

In the old days we put way too many fuses on the amps as we were concerned about the effects of tube failure. As time went by we got the number down to 3. The fuse by the power cord blows if the amp tries to make too much power, and this has proven very effective for speaker protection since we started using this system, which was about 25 years ago or so. The amps are warranted 3 years (although we are not particularly picky about that and the warranty is transferable) and tubes are warranted for 1 year.

atmasphere, I found this article interesting. I do not claim to understand much of it, but appreciate and like what I do read/understand. It speaks even more specifically to your specific implementation of Circlotrons. There is even a blurb about loudspeaker safety as well (in addition to what you have previously stated). To an extent I would consider you a pioneer in your field. Not sure if you had anything to do with the text portion of this article, but you and your company are credited throughout. 

https://en.wikipedia.org/wiki/Circlotron





I stand corrected.  My OTL amps were indeed produced by Fourier Components in the late 1990s.  BTW, to my knowledge, Atma-Sphere is one of the few, if only, OTL amp companies to survive for any length of time.  Probably a testament to their reliability.  Most of the others, NYAL, Futterman, Fourier Components, Counterpoint, Silvaweld, Prodigy, for example, have gone bankrupt.  I sense a trend here.
^^ Thanks for that, I don't recall ever seeing that page before. It has some omissions (probably should have mentioned GAS and BAT, no mention of Graaf, who was the only Circlotron amp manufacturer to employ the Cecil Hall circuit in modern times) and certainly glosses over some detail (as the Cecil Hall amplifier was a bit of a variant compared to what's shown on that page). 
I came home one time, and I found my M-60 Mk II's in BED with my Spendors...I will never get the image out of my mind, and I sold them both the next day. By far the most two-faced, untrustworthy amps I've ever bought.
Were they having, uh, group delay?

I have some Atmasphere Novacrons mated with Classic Audio 3.3 speakers in a 20X18 room that just sound fabulous. Very reliable 
I built a pair of M60s 20 years ago and they're still going strong.  I did send them back to Ralph for an upgrade and to check them out a couple years ago.  I highly recommend them--rock solid performance.
P.S. Atmaspheres do like a higher speaker impedance--I use Paul Speltz Zero autoformers as speaker wires, which bring the impedance of my Kef Reference 207/2s up to a respectable ~8 Ohm minimum and 14 Ohm avg which increases the output of the amps up into the 70W range.
Wait…can't I simply get a screwdriver and remove the transformers from my amps? And where do all the unused transformers go? Is there a pile somewhere? Is there an opposite amp that is ALL transformers? These are the sort of sophisticated questions that need to be asked…impedance imschmedance!
Wolf, yes you can remove the transformers from your amps.  Please do that today and send them to me.  I'll find a good use for them. :)


If I ever went with a tube amp, I'd seriously consider Atmasphere amps.

Like Markus1299, one of the best sounding systems I've EVER heard was Atmasphere/Classic Audio at RMAF a few years ago.

If I had a giant room for those speakers, and the money of course, I'd absolutely replicate that system.  It was AWESOME.

Not to mention Ralph is a great guy who makes fantastic products.
I have owned M60s for 17 years.  I first purchased them as a kit, and then I had them upgraded in 2007.  I have changed the tubes once in all that time.  They were absolutely reliable even though I drove some difficult loads with them.  I used them to drive my Quad 2805s.  I also want to say that heat has never been an issue.  The 100W Wavestream Kenetics Boxters that I am using now to the drive the Quads generate much much more heat.  They are standard push-pull amps based on 4 6550s (KT88s) each. 
Well, I can tell you they are one of the best amplifiers and pre-amps in the audio world if not probably the best available at down to earth prices. In my setup they have outclassed many more expensive Tube gear.
Atma-Sphere Customer service is one of the best in the industry and warranty upgrades is too. Iv never had any issues owning Atma Gear or having experiences with Failure. 

Ralph is well respected around these forums and always answers emails with any questions you may have.

It may be advisable to research about Atma-Sphere posts first before you make such comments about the company. They have been in business longer than I have been alive on this planet. I spent months researching about Atma-Sphere many years ago before I decided to place orders for a full setup. Comparing them to VAC, BAT, CAT, PASS and many other audio companies I never have had much satisfaction except with Atma.

Proper matching is required for the Power Amplifiers to Speakers, however even the Pre-Amps can outclass many more expensive audio gear even 4 times its price. Something to ponder on. If your in the USA, I would urge you to fly over to Atma and hear for your self.


I’ve seen a lot of people site the fact that Atma-Sphere’s products are sensitive to speaker choice. I’m currently looking at buying Zu Soul Supremes and they are a very high efficiency two way 16 ohm speaker. The s30 is on my short list of options and the only OTL as all other considerations are SETs.
I believe Atma-Spere is going to be at RMAF so I can definitely talk to them there, but I was wondering if any one would have input on the subject for me?
What are you guys running/liking with their products?
Clearly the troll that started this thread has gone underground where he belongs. I sure hope he stays there.
@cottguyWe've had good luck running ZU loudspeakers at our facility; in terms of efficiency and impedance they are very similar to the loudspeakers we will be using at the RMAF.

This thread is interesting and informative. I have owned Solid State and Tubes amps from many manufacturers over the years, but I have never owned Atmasphere amps (or any other OTL) for that matter. I would like to try them some day. As for the gentlemen that made the statement about tube amps "...Tube components indeed sound different, but they're just toys and nothing serious no matter of reputation or credibility of one or another manufacturer..." he may be on the wrong forum. Sounds like he may be better suited to shop and have discussions with the folks in the electronics section at WalMart. But then again, everyone is entitled to their opinion.