Today I picked up my Atma-Sphere Class D Amps. These aren’t broken in yet. And they are simply amazing. I’ve listen to a lot of High End Class D. Some that cost many times what Atma-Sphere Class D costs. I wasn’t a fan of any of them. But these amps are amazing. I really expected to hate them. So my expectations were low. The Details are of what I’ve never heard from any other amps. They are extremely neutral. To say the realism is is extremely good is a gross understatement. They are so transparent it’s scary. These amps just grab you and suck you into the music. After I live with them some and get them broken in. And do some comparisons to some other high end Amps Solid State, Tubes and Class D’s, also in other systems I’ll do a more comprehensive review. But for now, these are simply amazing amps.. Congrats to Ralph and his team. You guys nailed on these.
While these rules of thumb are helpful perhaps to people such as yourself designing amplifiers aimed at as broad a segment of the market as possible, they are not "laws" or universally applicable "truths" like the law of conservation of energy or the laws of thermodynamics. As a result, they can not be relied upon on to be an accurate predictor on an individual basis. Thus, the guy shelling out $5K for an amp would be best advised to trust his own perceptions and tastes and to listen to the amp in his system, in his room, to form his opinions rather than rely on the perceptions, tastes, and opinions of others.
Fletcher Munson is a bit more variable, but the masking principle isn't. Its what made MP3s possible. Also, how humans sense sound pressure does not change from individual to individual; generally, the higher ordered harmonics are used. This is really easy to demonstrate using simple test equipment. Imagine a world where every individual used entirely different hearing perceptual rules! It would be a good basis for a scifi novel 😉
The patent involves the use of a Circlotron to reduce deadtime. If you are using GaNFETs, the inductive kick of the output filter coil is what really turns the device off (assuming the gate is already off); to allow that to happen a certain amount of deadtime has to exist. As it is there is still less deadtime in a GaNFET design as opposed to a MOSFET design.
Too many don't understand the difference between their subjective opinions and objective fact.
Being objective is a worthy struggle despite it being impossible.
FWIW we've done lots of comparisons and we have a lot of feedback from the field at this point- from a variety of customers that know our prior work. The feedback is surprisingly consistent, in the face of not knowing about any other feedback we've received.
I would have thought by now my point had been made.
Yes to both your questions.
No harm in using forums to learn of new gear. One needs to read critically and take the subjective opinions with a grain of salt. When it is all subjective opinion there isn’t much sense that can be made of it if you are a rational actor. Too many don't understand the difference between their subjective opinions and objective fact.
If a bunch of people with speaker-X say that they like electronics-A, B and C, then I think to myself, “I should see if I like them.”
If I do not like speaker-Y and a bunch of people say electronics-C, D, and E are great, then and not sure what I should with that… especially with D and E.
As there are more electronics that one can often stumble across we use other peoples observations and opinions on a forum to make some sense of it, and get exposed to things which we may not find, or otherwise know to look for.
But if we assume that some amps were possible with a vanishingly low THD+N, then they would sound the same regales of topology
There are indeed those who claim once a certain level of performance has been reached, then products would indeed be indistinguishable from one another. I believe there have been rather rigorous tests done which seem to bear this out.
As I said, Fletcher-Munson and other such empirical studies have predictive power in a general sense but are weak on an individual basis. Additionally, personal preferences when it comes to audio gear is not based solely on sound, in any case. There are several other factors buyers consider when making a purchase which factor into a decision. It’s a complex decision that one needs to ultimately make for one’s self in the proper context.
Sure, a person could choose a proxy and take a chance. It all depends on risk tolerance and finding a suitable proxy. Me, I prefer to judge for myself as finding someone else with my tastes, the same gear and acoustical space, would be more difficult, time consuming, and risky than just trying the equipment myself. Besides, even if I associated myself with a "like minded group", the critical issues of component interaction and acoustical interaction in my space would make it impossible to find a realistically "safe" bet.
I don't believe your analogy is appropriate, either for those "cable deniers" who base their argument primarily on an intellectual argument- it's a belief system, not a perception driven matter of taste, nor for those who simply claim that they hear no differences. That is more a pure perception argument rather than a matter of taste. In either case, it isn't a simple matter of taste at work, unlike the debates centered on amps, etc.
Strictly speaking, Fletcher-Munson and the like are not rules or laws, but rather experimentally derived models of human aural perception. They are built on averages and generalities- in the case of Fletcher-Munson the results are said to apply to "average young people without significant hearing impairment". I doubt that describes many of those reading this thread... They have also been revised numerous times. While these rules of thumb are helpful perhaps to people such as yourself designing amplifiers aimed at as broad a segment of the market as possible, they are not "laws" or universally applicable "truths" like …
In terms of universal truths and laws, one can pretty safely say that as the distortion products go to zero, that the fidelity improves. How well this happens with complex loads, etc. is where topologies matter. But if we assume that some amps were possible with a vanishingly low THD+N, then they would sound the same regales of topology
… the law of conservation of energy or the laws of thermodynamics. As a result, they can not be relied upon on to be an accurate predictor on an individual basis.
Statistics, stereotype and generalities are borne from things being similar.
Humans are tuned to those sorts of easy ways to categorise things.
And the statistics of a group, are indicative if the sum of the individual biases and likes/dislikes.
Thus, the guy shelling out $5K for an amp would be best advised to trust his own perceptions and tastes and to listen to the amp in his system, in his room, to form his opinions rather than rely on the perceptions, tastes, and opinions of others. Of course there are always those who love to gamble.
And thus if one considers themselves similar to others in the group, then they would be more wise to gamble that what other people like, that they will also find that they the same stuff.
and likewise if they find that they are at odds with the group, then they would likely deviate from the group perspective.
An example would be cable deniers or believers.
If one identifies as a cable believer, then other cable believer perspectives likely have more bearing, and theuy find speaker cables, IC and power cables all matter.
And for the cable denier, they likely find similarity with other cable deniers, and value their similar group’s inputs.
and some probably find no difference in XLRs and power cords, but could believe that speaker cables make a difference, and identify with their brethren/sisters.
There are the rules of human hearing perception (such as Fletcher Munson or the masking principle) and there is taste. They are two very different things and the two get conflated quite often! All humans use the same hearing perceptual rules- otherwise audio as an art would be impossible. What people do with that is different, which is why there is disco, rap, classical, tone controls and the like. Human physiology responds the same way to distortion, so it is something that is predictable and reliable within certain limits (there is individual variance on how the 3rd is perceived, depending on its phase for example).
Strictly speaking, Fletcher-Munson and the like are not rules or laws, but rather experimentally derived models of human aural perception. They are built on averages and generalities- in the case of Fletcher-Munson the results are said to apply to "average young people without significant hearing impairment". I doubt that describes many of those reading this thread... They have also been revised numerous times. While these rules of thumb are helpful perhaps to people such as yourself designing amplifiers aimed at as broad a segment of the market as possible, they are not "laws" or universally applicable "truths" like the law of conservation of energy or the laws of thermodynamics. As a result, they can not be relied upon on to be an accurate predictor on an individual basis. Thus, the guy shelling out $5K for an amp would be best advised to trust his own perceptions and tastes and to listen to the amp in his system, in his room, to form his opinions rather than rely on the perceptions, tastes, and opinions of others. Of course there are always those who love to gamble.
I see that you haven't made any comments addressing the patent that you received related to this amp, nor related why you have yet to publish any measurement plots, etc. Having this on the market now for a while, I would have hoped that info would have been forthcoming. Perhaps the transparency of Hypex and Purifi has spoiled me.
Again, thanks for your time. And best wishes on the success of your product.
Really appreciate your insightful experience and comments.
I am thankful that you brought Class D to the market and that it has been so well received. I run Class D myself, though it is not the typical Class D amp - it is the TAD M2500. In the process of choosing an amp, I listened to Luxman, Pass, Burmester (very good), and maybe one or two others, I forget, and the TAD was the best that fell into my budget - only the Burmester 909 with matching 077 preamp was better, but at $$ multiples of the M2500 + C2000 pre. This pairing makes my TAD E-1s sing and I’m sure part of that is system/manufacturer synergy, but if Class D were not good, the system would not be sublime like it is.
I hope the more manufacturers will make high quality Class D amps, glad you’ve beat nearly all of them to the punch.
Thanks again for being the gentlemen and sharing your decades of experience with us all.
Would you mind reiterating your past comment of how Class D (yours and perhaps others) have finally made the leap to outperform tubes (yours and others)?
I find the class D to be more transparent in my system compared to my tube amps; less coloration also due to lower distortion. At the same time I don't find them harsh, a classic sin of solid state amps in general. I can play them all day and not get tired of them.
Now let's say you are a tube amp producer. You face a variety of problems. Right now a major one is availability. If you're not going to get in trouble with the law (due to sanctions against Russia), you're probably using Chinese or JJ tubes if you're using new tubes. Another one is the industry is tending towards 4 Ohms as the default speaker impedance rather than 8; I see this as a bad thing since all amps make greater distortion into lower impedances, and with many its enough to be heard (audiophiles use 'fat' 'muddy' and other similar expressions for this). But 4 Ohms is a thing regardless of what I think.
Its now possible to build a solid state amp that is as relaxed as a good tube amp, not lacking detail or depth (and maybe more). Since brightness and harshness of solid state is what has kept tube amp producers in business for the last 60 years, and also because tube amplifier power is more expensive, how long will tubes be a viable option in audio? IMO while it will still be a while (owing largely to highly variable results designers got out of class D over the last 20 years having poisoned the well at first) tubes will continue for a while, but even chip-based class D amps that might only be $75.00 are now giving serious tube amps a run for the money!
If I were an amplifier manufacturer that had not got the class D thing figured out, right now I would be worried. The market will be shrinking for tube power products- even in the guitar world. I know a lot of cheap class D guitar amps are so much junk but they aren't all that way, and most guitarists these days rely on their effect pedals for their 'sound'. The guitar market is a lot larger than the high end audio market for tube use- they drive a lot of what is available for high end as a result. If you lose the guitar market, that will be very nearly the end of tubes.
As always your explanations and insight are most appreciated and welcome. I agree with your “no accounting for taste “ as this is true. Be it audio components/music genre/food or automobiles etc. as human beings, We like what we like. 😊
Thus the multitude of choices available in our lives,
Would you mind reiterating your past comment of how Class D (yours and perhaps others) have finally made the leap to outperform tubes (yours and others)?
thx
Testing has indicated correlations between certain distortion spectra and "averaged" or group perceptions but there has been no perfect correlation established between measurements and human response on an individual basis because at the end of the day, you just can’t account for taste.
There are the rules of human hearing perception (such as Fletcher Munson or the masking principle) and there is taste. They are two very different things and the two get conflated quite often! All humans use the same hearing perceptual rules- otherwise audio as an art would be impossible. What people do with that is different, which is why there is disco, rap, classical, tone controls and the like. Human physiology responds the same way to distortion, so it is something that is predictable and reliable within certain limits (there is individual variance on how the 3rd is perceived, depending on its phase for example).
I wasn’t aware that class D amplification was doable without the utilization of negative feedback
@charles1dadIt is. Our first prototypes were all zero feedback and demonstrated to us that the idea of class D was worth pursuit. You also don’t need opamps- again we drove early prototypes directly using our preamps, which have no trouble driving lower impedances like 2000 Ohms. These prototypes didn’t use any opamps.
You can’t seem to get beyond the simple truth that your experienced subjective reality and beliefs are nothing but opinions and are no more valid than anyone else’s. The guru complex.
+1 AGS, Audiophile Guru Syndrome, is an ugly thing :)
His high feedback Op-amps amplifier versus a near polar /opposite approach is something that I find compelling with regard to respective sonic presentation. All that concerns me with audio products is how do they sound? That’s why we buy them.
The reason for both approaches is the same. IMO/IME the amp must not have any increase in distortion as the test frequency is increased. Most amps using feedback suffer this problem- and they sound brighter and harsher than they should partially on that account. In a tube amp, getting it to run enough feedback to get around this problem is impossible regardless of the topology. This is because they lack the Gain Bandwidth Product to support the feedback at higher frequencies- as you increase frequency, the amp requires a lot of GBP; if its not there the feedback will fall off, causing distortion to rise. We avoided that in our OTLs by running them zero feedback.
This is a problem in solid state too- and is part of why traditional solid state amps are known to sound bright and harsh (especially at higher volume). Class D offers a way around this because you can get the loop gain you need to really support a high GBP value- and thus also support high feedback at all audio frequencies.
The reason feedback can be problematic is that the feedback node always has a non-linearity associated with it. This might be the base of a transistor, or the cathode of a tube; whatever it is means the feedback signal is distorted by that non-linearity and so when mixed with the incoming signal doesn’t quite do what its supposed to do (one effect of this is additional distortion is created...). But if you run enough feedback you start to get around this problem. That needs to be at a minimum 30dB and must be 30dB at all audio frequencies. We’re at about 37dB.
Probably more information than you were expecting, and actually IMO this explanation is really the nutshell version so those of you technically-minded I am aware this explanation is incomplete.
If the desire is for more emotion ,soul, humanity, breathe of life type of sound, a high quality SET or OTL is very difficult to match. It just always depends on what you want. Other topologies will excel in other specific sonic parameters/areas.
I think one of the issues you run into when making this comparison is that the zero feedback tube amps (whether SET or OTL) will have a frequency response variation depending on the load impedance (the speaker). I’ve found that anyone using such equipment, including myself, has made accommodations for that issue if they have spent any time trying to make their system sound neutral and musical at the same time. In my case this is mostly to do with the level settings for the drivers, found on the rear of my speakers. I use pink noise to set them up correctly. Whatever those accommodations are though, you have to back them out of your system if you really want to do a proper comparison, which is probably tricky. This is just a personal observation, but once I corrected my system for the voltage response of the class D I found it every bit as involving.
I would like to hear the designer’s take on how his class d design differs from those of Hypex and Purifi and at 3 to 4 times the price, what they offer over the Hypex and Purifi products that makes them worth the considerable difference. I would like to know why he decided to design his own class d modules, especially in light of the fact that it is no trivial matter and a completely different task than designing a tube amp....I would like to know why the designer choose GaNfets over standard fets and what advantages he believes they offer at his operating frequency over standard fets....
We chose to design our own module because it sends the wrong message to the marketplace by using someone else’s- it suggests that maybe you don’t don’t have the engineering talent in-house. Plus we can make it the way we want to. FWIW our modules seem to be lower noise than Bruno’s.
The reason we’ve not used SMPSs yet is we found that if you really want the amp to perform properly, especially at high volume, the SMPS really needs to be designed specifically for the application. Most of our prototypes ran SMPSs and we ran into this limitation quite frequently.
A good portion of our cost is the chassis, which is custom-built and designed to look decent, not man-cave and also be durable in shipment. It seems its a bit over-built! For the last 40 years we’ve gotten dinged on cosmetics a lot; you put in the cosmetics and then you get dinged on price...
GaNFETs are a little faster, but the main reason for using them is to create a lower noise layout due to less strays and lower drive requirements which are for the most part an order of magnitude lower than MOSFETs. In this regard the noise our amps put out on the AC line is lower than many tube amps and most of that comes from the power rectifiers rather than anything to do with the module.
@tinear123 Don’t give up now! It is pretty easy to just ignore and not respond when there is no value to the posts. There are plenty of folks left who would value your perspectives.
I just cannot understand why stating your position and one possible retort with civility is not possible by some. You may be having fun being the bully of the playground, and smarter than everyone else, and while you may think you are teaching others, you are in fact disenfranchising those that are starting their audio journey and corrupting the social space this platform can enable and frankly killing the hobby.
Nice summation and sign off. Continue to enjoy the Atma-Sphere and Frankenstein amplifiers.
But I think the regulars have stopped feeding the trolls
Name calling when one doesn't agree with an idea or opinion is in fact the immature behavior being complained about. Too bad insecurity and ignorance ruined the thread.
the fiasco that this thread has become with the measurement vs perception "comments / pissing match" has reaffirmed my worst fears of what AGON has devolved into. Worse that small children.
Agreed @tinear123. But I think the regulars have stopped feeding the trolls. Good to read about your experience. Thanks for sharing.
One last comment then I’ll sign off. I have not been on AGON for about a year and since I was interested in the new Atma-Sphere Class-D I thought I would check to see what others were saying and stumbled on to this thread at page-2. When I secured a home demo opportunity, I thought I would give input to add to the community. That being said, the fiasco that this thread has become with the measurement vs perception "comments / pissing match" has reaffirmed my worst fears of what AGON has devolved into. Worse that small children. I just cannot understand why stating your position and one possible retort with civility is not possible by some. You may be having fun being the bully of the playground, and smarter than everyone else, and while you may think you are teaching others, you are in fact disenfranchising those that are starting their audio journey and corrupting the social space this platform can enable and frankly killing the hobby.
I don't think it is luck to have an amp that measures well and sounds good. I think it is the goal of many skilled engineers/designers. There are plenty of amps that measure very well and are very successful in the marketplace. There are also many that measure poorly in comparison, and yet they too find their supporters. If one didn't know better one might be tempted to believe that people's tastes vary quite significantly and that "good" and "not good" perceptions are relative to the individual, not the gear.
@kuribomy attempt at sarcasm or sardonicism may have been too well disguised.
Unfortunately, no I have not tried the PS M-1200 it would be severe overkill for my horn application as was the M-700. That being said I did hear it back to back with the PS-BHK300 on Wilson Sasha DAW and my preference was the M-1200. If you need the power might be a solution especially with the tube rollable input stage.
Funny you mentioned this as it was on my mind for this morning... I will say the cheapo Crown did spank the PS M-700 previously leaving me shocked. I was so sure the PS would crush the Crown that I dug out the Crown box from the attic before installing the M-700s... then 3 days later took the Crown box back to the attic and sold the M-700s.
When you listed your system, it looked to me that the Atma-Sphere amps would be the best fit to replace your Crown-XLi-1500 bass amp. The Reference Compact cabinets in my experience respond well to the best amplification possible.
(I have a pair of BD-Design Reference Compact bass cabinets I built years ago -- they are in storage).
Although perhaps your configuration is such that it would be hard to replace the Crown for some reason? If not, you may want to try a swap.
@tinear123you mentioned these Atma-sphere's class D being in the realm of PS Audio m700. I've been considering the M1200's with a tube input. Have you heard these? Would you care to explain how the same or different the Atma-sphere may be vs the PS Audio monoblocks?
Thanks for your review. The Frankie’s are a great amp. And as you said excel in certain areas. I figured your review would be as such. As the AS Class D aren’t as good as my MA-1’s in the same areas. But your findings are basically mirror mine when comparing my MA-1’s.
No surprises, and experienced listeners know that no amplifier/audio component is flawless. You listen and choose what suits you best and provides the higher degree of joy and pleasure, accepting inevitable compromises.
If the desire is for more emotion ,soul, humanity, breathe of life type of sound, a high quality SET or OTL is very difficult to match. It just always depends on what you want. Other topologies will excel in other specific sonic parameters/areas.
Ralph seems to have an amp that measures well and sounds great.
It seems like a lucky outcome to achieve both at once
Since he hasn't to my knowledge published the measurements I couldn't say it measures well or not. It seems to sound great to some, but every amp on the market sounds great in the minds of some people.
I don't think it is luck to have an amp that measures well and sounds good. I think it is the goal of many skilled engineers/designers. There are plenty of amps that measure very well and are very successful in the marketplace. There are also many that measure poorly in comparison, and yet they too find their supporters. If one didn't know better one might be tempted to believe that people's tastes vary quite significantly and that "good" and "not good" perceptions are relative to the individual, not the gear.
Thanks for your review. The Frankie’s are a great amp. And as you said excel in certain areas. I figured your review would be as such. As the AS Class D aren’t as good as my MA-1’s in the same areas. But your findings are basically mirror mine when comparing my MA-1’s. But there is no heat for summertime listening. Which is a bonus. Thanks again expressing your view point.
Follow Up... While it sounds like I will never leave the 300B world please note that there is no turntable in my system after 25 years the Innuous streamer enabled divesting vinal 2 years ago and I’m perfectly happy with streaming.
All... my initial report out of the Atma-Sphere-D compared to my Coincident Frankenstein Mk-2 300B amps. I listened for 11 hours yesterday deep into the night using a pattern of 2 hours between swapping then repeat. One thing to remember is in my system these amps are only driving my mid/high horns so from 300Hz to 21kHz thus I cannot speak to low frequency performance.
I generally listen to blues and classic rock so Etta James, The Commitments, BB King, Marsha Ball, Boney James, Diana Krall, Greg Porter, Eagles, Joe Walsh, Lenny Kravits, Los Lobos, Prince, Stevie Ray Vaughn, Van Morrison, 38 Special, ACDC, Beck, Boston, Chicago, Etc.
The AP-D frankly sounded very good and has a number of strengths as compared to my Frankies. First and foremost, the grip they had on my speakers was immediately apparent with mush improved transients and leading-edge crispness. High frequencies are clean and extended without being sharp and had more energy than my Frankies but the surprise for me was the increased power in the lower midrange to the point where I had to adjust my miniDSP xover for my LF amp to dial down the output curve in the 200Hz to 950Hz range. Of special note is the APD amps are dead quite even with my 112dD efficient horns.
The downside was that the 300B Frankies spanked the APD in the midrange as one would expect since this is the strength of 300Bs with a fuller more textured presentation with bloom and air. While the APD had good soundstage depth & width again the 300B Frankies are king of the road here as well.
In summary: I think the APD is much more accurate than the Frankies and would accel in most any system and I suspect they have authoritive base given the additional low extension power they provided with my mid-high horns. As for me, I think I may have been in the 300B world too long to walk away from the luscious midrange even with their shortcomings in ultimate accuracy. Special thanks to my dealer Koby at HiFi Logic in NJ for his flexibility for working me in.
The Atma-Sphere D's are in good company with the FirstWatt F7, FirstWatt SIT3, Cary 805C, PS-Audio M700, Benchmark AHB2 that have challenged the Frankies. I will continue to search from time to time for a suitable solid-state tube amp replacement.
@holmz I'm talking about stacking them on top of each other, on one rack shelf. The company that makes my class D amp often shows their monoblocks stacked. but reviewers and owners say it reduces sound quality. I tend to prefer short interconnects and longer speaker wires for system architecture.
That would put you in the minority.
Usually speaker wires/cables are better as the length goes to zero, and the XLRs are designed to handle longer runs.
But it would be a good question for the s designer to answer. <— @atmasphere
@holmz I'm talking about stacking them on top of each other, on one rack shelf. The company that makes my class D amp often shows their monoblocks stacked. but reviewers and owners say it reduces sound quality. I tend to prefer short interconnects and longer speaker wires for system architecture.
@pstores, the things similar to what you say about atmosphere class d amplifier was earlier declared in different threats in respect with the Peachtree GaN 400 and Voyager GaN 350 amplifiers, in particular. It is difficult to visualize the extent of your observations without making a direct AB comparison with one of the above or other similar GaN amplifiers (these two are almost equivalent). You mentioned about some Peachtree amplifiers that you had, but you didn't said if it was GaN 400 and if you did an AB comparison. That kind of report would really be useful. Otherwise you are saying nothing particularly new.
OP, did you say you had listened to some of the current generation Class non-GaN D amps from Hypex, Purifi, or Pascal? Are those all ones you felt were dry etc.?
The only ones I have heard to date were the AGD, also GaN, not in my own system. They were completely clean, clear and enjoyable.
Seems a shortage of such in this thread which is overpopulated with small minded intellectually feeble name callers who can neither rationally defend their position nor accept any idea which might challenge their misconceptions.
I am not sure that it is helpful to refer to them as small minded and intellectually feeble.
They may appear feeble in mathematics and and engineering, but they could have other skills, which we may not posses…
And on the other side, we have the “everything matters” tribe, and “my ears are all that counts” group.
Ralph seems to have an amp that measures well and sounds great.
It seems like a lucky outcome to achieve both at once. 😎
… and it makes me wonder how he did that.
Seems a shortage of such in this thread which is overpopulated with small minded intellectually feeble name callers who can neither rationally defend their position nor accept any idea which might challenge their misconceptions.
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